Move to gawk-3.0.2.gawk-3.0.2

35 files changed, 19607 insertions, 736 deletions

diff --git a/ChangeLog b/ChangeLog
index c084177f..53ce6f7d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,48 @@
+Wed Dec 25 11:25:22 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.2: Release tar file made.
+
+Wed Dec 25 11:17:32 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Makefile.in (install, uninstall): use $(srcdir)/patchlevel.h.
+	  Thanks to Richard Levitte, LeViMS@stacken.kth.se.
+	  (install): remove chmod command; let $(INSTALL_PROGRAM) use -m.
+
+Mon Dec 23 20:36:59 1996  Pat Rankin  <rankin@eql.caltech.edu>
+
+	* custom.h (#if VMS_POSIX):  Define GETPGRP_VOID.
+
+Fri Dec 20 08:59:55 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* getopt.c, getopt1.c: comment out the `#if defined (_LIBC) ||
+	  !defined (__GNU_LIBRARY__)' and `#endif' to force use of this
+	  getopt, even on systems like linux.  This will be handled
+	  better in 3.1 / glibc 2.
+
+Thu Dec 19 22:52:39 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* awk.y (yylex): In several places, after yyerror(), add call to
+	  exit(). Otherwise, infinite messages. This should probably
+	  be handled better.
+
+Wed Dec 18 22:42:10 1996  Darrel Hankerson  <hankedr@mail.auburn.edu>
+
+	* getopt.c (_getopt_internal): if 'W' and ';', if optind == argc,
+	  return c, don't fall through.
+
+Wed Dec 18 10:09:44 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* configure.in [AC_PREREQ]: Update to 2.12 in order to switch to
+	  autoconf 2.12. Lots of other files will be rebuilt automatically.
+	  [AM_SANITY_CHECK_CC]: Removed, autoconf does it now.
+	* alocal.m4 [AM_SANITY_CHECK_CC]: Removed, autoconf does it now.
+
+Tue Dec 17 22:23:16 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* builtin.c (do_strftime): fix case if format string is "".
+	  Also fix it if format is not "" but result of strftime is "".
+	  See comments in code.
+
 Tue Dec 10 23:09:26 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
 
 	* Release 3.0.1: Release tar file made.
@@ -39,7 +84,7 @@ Thu Nov  7 20:54:43 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
 
 Thu Nov  7 09:06:21 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
 
-	* awk.y (snode): undo 4 Oct change, put do_split code.
+	* awk.y (snode): undo 4 Oct change, put do_split code back.
 	  field.c (do_split): restore old code; add test for CONST, so
 	  that re_parse_field is used if third arg to split is a regexp
 	  constant.
diff --git a/Makefile.in b/Makefile.in
index 7082fc30..40ccf8e7 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -172,8 +172,8 @@ alloca.o:	alloca.c
 
 install:	gawk info installdirs
 	-rm -f $(bindir)/gawk
-	fullname=gawk-$(REL).`./gawk '{print $$3}' patchlevel.h` ; \
-	$(INSTALL_PROGRAM) gawk $(bindir)/$$fullname && chmod 775 $(bindir)/$$fullname ; \
+	fullname=gawk-$(REL).`./gawk '{print $$3}' $(srcdir)/patchlevel.h` ; \
+	$(INSTALL_PROGRAM) gawk $(bindir)/$$fullname ; \
 	(cd $(bindir); $(LN) $$fullname gawk)
 	(cd $(bindir); \
 	if [ ! -f awk ]; \
@@ -189,7 +189,7 @@ installdirs: mkinstalldirs
 uninstall:
 	(cd $(bindir); \
 	if [ -f awk ] && cmp awk gawk > /dev/null; then rm -f awk; fi)
-	(fullname=gawk-$(REL).`gawk '{print $$3}' patchlevel.h` ; \
+	(fullname=gawk-$(REL).`gawk '{print $$3}' $(srcdir)/patchlevel.h` ; \
 	cd $(bindir); \
 	if cmp gawk $$fullname; then rm -f gawk; fi ; \
 	rm -f $(bindir)/$$fullname)
diff --git a/NEWS b/NEWS
index 98a01a3c..f0a2819d 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,17 @@
+Changes from 3.0.1 to 3.0.2
+---------------------------
+
+Gawk now uses autoconf 2.12.
+
+strftime now behaves correctly if passed an empty format string or if
+the string formats to an empty result string.
+
+Several minor compilation and installation problems have been fixed.
+
+Minor page break issues in the user's guide have been fixed.
+
+Lexical errors no longer repeat ad infinitum.
+
 Changes from 3.0.0 to 3.0.1
 ---------------------------
 
diff --git a/README b/README
index ddbd7110..30c7839f 100644
--- a/README
+++ b/README
@@ -1,10 +1,10 @@
 README:
 
-This is GNU Awk 3.0.1. It should be upwardly compatible with the Bell
+This is GNU Awk 3.0.2. It should be upwardly compatible with the Bell
 Labs research version of awk.  It is almost completely compliant with
 the 1993 POSIX 1003.2 standard for awk.
 
-Patch 1 just fixes bugs -- see NEWS for details.
+Patches 1 and 2 just fix bugs -- see NEWS and ChangeLog for details.
 
 See the file INSTALL for installation instructions.
 
diff --git a/README_d/README.sco b/README_d/README.sco
new file mode 100644
index 00000000..f40cf646
--- /dev/null
+++ b/README_d/README.sco
@@ -0,0 +1,22 @@
+Tue Dec 24 22:41:39 EST 1996
+
+SCO's awk has a -e option which is similar to gawk's --source option,
+allowing you to specify the script anywhere on the awk command line.
+
+This can be a problem, since gawk will install itself as `awk' in
+$(bindir). If this is ahead of /bin and /usr/bin in the search path,
+several of SCO's scripts that use -e will break, since gawk does not
+accept this option.
+
+The solution is simple. After doing a `make install', do:
+
+	rm -f /usr/local/bin/awk	# or wherever it is installed.
+
+This removes the `awk' symlink so that SCO's programs will continue
+to work.
+
+If you complain to me about this, I will fuss at you for not having
+done your homework.
+
+Arnold Robbins
+arnold@gnu.ai.mit.edu
diff --git a/aclocal.m4 b/aclocal.m4
index 3070af39..0184e83f 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -132,50 +132,3 @@ eate executables.]) ;;
 esac
 AC_MSG_RESULT(yes)
 ])dnl
-
-
-dnl To: Keith Bostic <bostic@bsdi.com>
-dnl Cc: bug-gnu-utils@prep.ai.mit.edu
-dnl Subject: Re: autoconf-2.7
-dnl From: Jim Meyering <meyering@asic.sc.ti.com>
-dnl Date: 15 Oct 1996 11:57:12 -0500
-dnl 
-dnl | The assumption that, if a simple program can't be compiled and
-dnl | run, that the user is doing cross-compilation, is causing me
-dnl | serious grief.  The problem is that Solaris ships a cc command
-dnl | that just fails, if you haven't bought their compiler.
-dnl | 
-dnl | What the user is eventually told is that it's not possible to
-dnl | run test programs when cross-compiling, which doesn't point them
-dnl | at the right problem.
-dnl | 
-dnl | Maybe it's just me, but I don't know too many normal users that
-dnl | do cross-compilation.  I'd like to see a more stringent test to
-dnl | decide if we're doing cross-compilation.  (Maybe with a message
-dnl | to use gcc!?!?  ;-})
-dnl 
-dnl Now I put this line in configure.in files:
-dnl 
-dnl AM_SANITY_CHECK_CC
-dnl 
-dnl Here's the macro that goes in aclocal.m4 -- it should be in the
-dnl next official release of automake.
-
-AC_DEFUN(AM_SANITY_CHECK_CC,
-[dnl Derived from macros from Bruno Haible and from Cygnus.
-AC_MSG_CHECKING([whether the compiler ($CC $CFLAGS $LDFLAGS) actually works])
-AC_LANG_SAVE
-  AC_LANG_C
-  AC_TRY_RUN([main() { exit(0); }],
-             am_cv_prog_cc_works=yes, am_cv_prog_cc_works=no,
-             dnl When crosscompiling, just try linking.
-             AC_TRY_LINK([], [], am_cv_prog_cc_works=yes,
-                         am_cv_prog_cc_works=no))
-AC_LANG_RESTORE
-case "$am_cv_prog_cc_works" in
-  *no) AC_MSG_ERROR([Installation or configuration problem: C compiler cannot cr
-eate executables.]) ;;
-  *yes) ;;
-esac
-AC_MSG_RESULT(yes)
-])dnl
diff --git a/amiga/ChangeLog b/amiga/ChangeLog
index 570c031b..e025b89d 100644
--- a/amiga/ChangeLog
+++ b/amiga/ChangeLog
@@ -1,3 +1,11 @@
+Wed Dec 25 11:25:22 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.2: Release tar file made.
+
+Tue Dec 10 23:09:26 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.1: Release tar file made.
+
 Wed Jan 10 22:58:55 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
 
 	* ChangeLog created.
diff --git a/atari/ChangeLog b/atari/ChangeLog
index 562b6dea..df405455 100644
--- a/atari/ChangeLog
+++ b/atari/ChangeLog
@@ -1,3 +1,11 @@
+Wed Dec 25 11:25:22 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.2: Release tar file made.
+
+Tue Dec 10 23:09:26 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.1: Release tar file made.
+
 Thu Nov 21 13:11:20 1996  Michal Jaegermann  <michal@phys.ualberta.ca>
 
 	* Makefile.st: Once again Makefile.st and config.h chase
diff --git a/awk.y b/awk.y
index f855f254..ef7f4407 100644
--- a/awk.y
+++ b/awk.y
@@ -1416,8 +1416,10 @@ retry:
 		if (nextc() == '\n') {
 			sourceline++;
 			goto retry;
-		} else
+		} else {
 			yyerror("backslash not last character on line");
+			exit(1);
+		}
 		break;
 
 	case '$':
@@ -1584,6 +1586,7 @@ retry:
 			if (c == '\n') {
 				pushback();
 				yyerror("unterminated string");
+				exit(1);
 			}
 			if (c == '\\') {
 				c = nextc();
@@ -1597,6 +1600,7 @@ retry:
 			if (c == EOF) {
 				pushback();
 				yyerror("unterminated string");
+				exit(1);
 			}
 			tokadd(c);
 		}
@@ -1708,8 +1712,10 @@ retry:
 		return lasttok = '|';
 	}
 
-	if (c != '_' && ! isalpha(c))
+	if (c != '_' && ! isalpha(c)) {
 		yyerror("Invalid char '%c' in expression\n", c);
+		exit(1);
+	}
 
 	/* it's some type of name-type-thing.  Find its length. */
 	tok = tokstart;
diff --git a/awklib/ChangeLog b/awklib/ChangeLog
index 2fab5799..407ac2b5 100644
--- a/awklib/ChangeLog
+++ b/awklib/ChangeLog
@@ -1,3 +1,20 @@
+Wed Dec 25 11:25:22 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.2: Release tar file made.
+
+Wed Dec 25 11:17:32 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Makefile.in (install): remove chmod command; let
+	  $(INSTALL_PROGRAM) use -m.
+
+Tue Dec 17 22:29:49 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Makefile.in (install): fix installation of files in eg/lib.
+
+Tue Dec 10 23:09:26 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.1: Release tar file made.
+
 Sun Oct 20 12:30:41 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
 
 	* Makefile.in (install): minor tweaks for portability.
diff --git a/awklib/Makefile.in b/awklib/Makefile.in
index 87209881..895e8886 100644
--- a/awklib/Makefile.in
+++ b/awklib/Makefile.in
@@ -73,15 +73,16 @@ group.awk: $(srcdir)/eg/lib/groupawk.in
 	sed 's;/usr/local/libexec/awk;$(libexecdir);' < groupawk.in) > group.awk
 
 install: igawk $(AUXPROGS) $(AUXAWK)
-	$(INSTALL_PROGRAM) igawk $(bindir)/igawk && chmod 755 $(bindir)/igawk
+	$(INSTALL_PROGRAM) igawk $(bindir)/igawk
 	for i in $(AUXPROGS) ; do \
 		$(INSTALL_PROGRAM) $$i $(libexecdir)/$$i ; \
 	done
 	for i in $(AUXAWK) $(srcdir)/eg/lib/*.awk ; do \
-		$(INSTALL_DATA) $$i $(datadir)/$$i ; \
+		progname=`echo $i | sed 's;.*/;;'` ; \
+		$(INSTALL_DATA) $$i $(datadir)/$$progname ; \
 	done
 
-# libexecdir and bindir are removed in the top level Makefile's uninstall
+# libexecdir and datadir are removed in the top level Makefile's uninstall
 uninstall:
 	rm -fr $(libexecdir)/* $(datadir)/*
 	rm -f $(bindir)/igawk
diff --git a/awklib/eg/prog/split.awk b/awklib/eg/prog/split.awk
index e48653b4..593e3c64 100644
--- a/awklib/eg/prog/split.awk
+++ b/awklib/eg/prog/split.awk
@@ -4,8 +4,7 @@
 
 # usage: split [-num] [file] [outname]
 
-BEGIN    \
-{
+BEGIN {
     outfile = "x"    # default
     count = 1000
     if (ARGC > 4)
diff --git a/awktab.c b/awktab.c
index 9bda6804..40e274c2 100644
--- a/awktab.c
+++ b/awktab.c
@@ -1,47 +1,47 @@
 
-/*  A Bison parser, made from ./awk.y with Bison version GNU Bison version 1.22
-  */
+/*  A Bison parser, made from ./awk.y
+    by GNU Bison version 1.28  */
 
 #define YYBISON 1  /* Identify Bison output.  */
 
-#define	FUNC_CALL	258
-#define	NAME	259
-#define	REGEXP	260
-#define	ERROR	261
-#define	YNUMBER	262
-#define	YSTRING	263
-#define	RELOP	264
-#define	APPEND_OP	265
-#define	ASSIGNOP	266
-#define	MATCHOP	267
-#define	NEWLINE	268
-#define	CONCAT_OP	269
-#define	LEX_BEGIN	270
-#define	LEX_END	271
-#define	LEX_IF	272
-#define	LEX_ELSE	273
-#define	LEX_RETURN	274
-#define	LEX_DELETE	275
-#define	LEX_WHILE	276
-#define	LEX_DO	277
-#define	LEX_FOR	278
-#define	LEX_BREAK	279
-#define	LEX_CONTINUE	280
-#define	LEX_PRINT	281
-#define	LEX_PRINTF	282
-#define	LEX_NEXT	283
-#define	LEX_EXIT	284
-#define	LEX_FUNCTION	285
-#define	LEX_GETLINE	286
-#define	LEX_NEXTFILE	287
-#define	LEX_IN	288
-#define	LEX_AND	289
-#define	LEX_OR	290
-#define	INCREMENT	291
-#define	DECREMENT	292
-#define	LEX_BUILTIN	293
-#define	LEX_LENGTH	294
-#define	UNARY	295
+#define	FUNC_CALL	257
+#define	NAME	258
+#define	REGEXP	259
+#define	ERROR	260
+#define	YNUMBER	261
+#define	YSTRING	262
+#define	RELOP	263
+#define	APPEND_OP	264
+#define	ASSIGNOP	265
+#define	MATCHOP	266
+#define	NEWLINE	267
+#define	CONCAT_OP	268
+#define	LEX_BEGIN	269
+#define	LEX_END	270
+#define	LEX_IF	271
+#define	LEX_ELSE	272
+#define	LEX_RETURN	273
+#define	LEX_DELETE	274
+#define	LEX_WHILE	275
+#define	LEX_DO	276
+#define	LEX_FOR	277
+#define	LEX_BREAK	278
+#define	LEX_CONTINUE	279
+#define	LEX_PRINT	280
+#define	LEX_PRINTF	281
+#define	LEX_NEXT	282
+#define	LEX_EXIT	283
+#define	LEX_FUNCTION	284
+#define	LEX_GETLINE	285
+#define	LEX_NEXTFILE	286
+#define	LEX_IN	287
+#define	LEX_AND	288
+#define	LEX_OR	289
+#define	INCREMENT	290
+#define	DECREMENT	291
+#define	LEX_BUILTIN	292
+#define	LEX_LENGTH	293
+#define	UNARY	294
 
 #line 26 "./awk.y"
 
@@ -73,7 +73,8 @@ static NODE *make_param P((char *name));
 static NODE *mk_rexp P((NODE *exp));
 static int dup_parms P((NODE *func));
 static void param_sanity P((NODE *arglist));
-static int isnoeffect P((NODETYPE));
+static int isnoeffect P((NODETYPE t));
+static int isassignable P((NODE *n));
 
 enum defref { FUNC_DEFINE, FUNC_USE };
 static void func_use P((char *name, enum defref how));
@@ -105,7 +106,7 @@ extern int errcount;
 extern NODE *begin_block;
 extern NODE *end_block;
 
-#line 88 "./awk.y"
+#line 89 "./awk.y"
 typedef union {
 	long lval;
 	AWKNUM fval;
@@ -114,23 +115,6 @@ typedef union {
 	char *sval;
 	NODE *(*ptrval)();
 } YYSTYPE;
-
-#ifndef YYLTYPE
-typedef
-  struct yyltype
-    {
-      int timestamp;
-      int first_line;
-      int first_column;
-      int last_line;
-      int last_column;
-      char *text;
-   }
-  yyltype;
-
-#define YYLTYPE yyltype
-#endif
-
 #include <stdio.h>
 
 #ifndef __cplusplus
@@ -145,7 +129,7 @@ typedef
 #define	YYFLAG		-32768
 #define	YYNTBASE	62
 
-#define YYTRANSLATE(x) ((unsigned)(x) <= 295 ? yytranslate[x] : 107)
+#define YYTRANSLATE(x) ((unsigned)(x) <= 294 ? yytranslate[x] : 107)
 
 static const char yytranslate[] = {     0,
      2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
@@ -173,11 +157,11 @@ static const char yytranslate[] = {     0,
      2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
      2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
      2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
-     2,     2,     2,     2,     2,     1,     2,     3,     4,     5,
-     6,     7,     8,     9,    10,    11,    12,    13,    14,    15,
-    16,    17,    18,    19,    20,    21,    22,    23,    24,    25,
-    26,    27,    28,    29,    30,    31,    32,    33,    34,    35,
-    36,    37,    38,    39,    52
+     2,     2,     2,     2,     2,     1,     3,     4,     5,     6,
+     7,     8,     9,    10,    11,    12,    13,    14,    15,    16,
+    17,    18,    19,    20,    21,    22,    23,    24,    25,    26,
+    27,    28,    29,    30,    31,    32,    33,    34,    35,    36,
+    37,    38,    39,    52
 };
 
 #if YYDEBUG != 0
@@ -262,26 +246,30 @@ static const short yyrhs[] = {    83,
 
 #if YYDEBUG != 0
 static const short yyrline[] = { 0,
-   149,   157,   165,   181,   182,   183,   187,   189,   203,   205,
-   219,   225,   231,   233,   235,   248,   257,   259,   261,   271,
-   272,   276,   280,   291,   296,   305,   307,   316,   318,   336,
-   338,   343,   349,   357,   359,   364,   365,   369,   371,   373,
-   375,   377,   379,   381,   387,   391,   396,   399,   402,   404,
-   424,   463,   482,   484,   489,   491,   493,   507,   512,   514,
-   519,   524,   531,   533,   537,   538,   542,   544,   549,   551,
-   553,   555,   560,   562,   567,   569,   571,   573,   575,   581,
-   583,   588,   590,   595,   597,   603,   605,   607,   609,   614,
-   616,   621,   623,   629,   631,   633,   635,   640,   643,   648,
-   650,   655,   661,   663,   665,   671,   681,   689,   691,   697,
-   699,   701,   703,   705,   710,   713,   714,   716,   718,   724,
-   726,   728,   730,   732,   734,   736,   738,   743,   745,   747,
-   749,   751,   753,   755,   757,   759,   764,   766,   768,   771,
-   773,   781,   788,   789,   791,   793,   795,   798,   806,   817,
-   819,   824,   826,   834,   839,   843,   847,   851,   852,   856,
-   859
+   150,   158,   166,   182,   183,   184,   188,   190,   204,   206,
+   220,   226,   232,   234,   236,   249,   258,   260,   262,   272,
+   273,   277,   281,   296,   301,   310,   312,   321,   323,   341,
+   343,   348,   354,   362,   364,   369,   370,   374,   376,   378,
+   380,   382,   384,   386,   392,   396,   401,   404,   407,   409,
+   429,   468,   487,   489,   494,   496,   498,   512,   517,   519,
+   524,   529,   536,   538,   542,   543,   547,   549,   554,   556,
+   558,   560,   565,   567,   572,   574,   576,   578,   580,   586,
+   588,   593,   595,   600,   602,   608,   610,   612,   614,   619,
+   621,   626,   628,   634,   636,   638,   640,   645,   648,   653,
+   655,   660,   666,   668,   670,   676,   686,   694,   696,   702,
+   704,   706,   708,   710,   715,   718,   719,   721,   723,   729,
+   731,   733,   735,   737,   739,   741,   743,   748,   750,   752,
+   754,   756,   758,   760,   762,   764,   769,   771,   773,   776,
+   778,   786,   793,   794,   796,   798,   800,   803,   811,   822,
+   824,   829,   831,   839,   844,   848,   852,   856,   857,   861,
+   864
 };
+#endif
 
-static const char * const yytname[] = {   "$","error","$illegal.","FUNC_CALL",
+
+#if YYDEBUG != 0 || defined (YYERROR_VERBOSE)
+
+static const char * const yytname[] = {   "$","error","$undefined.","FUNC_CALL",
 "NAME","REGEXP","ERROR","YNUMBER","YSTRING","RELOP","APPEND_OP","ASSIGNOP","MATCHOP",
 "NEWLINE","CONCAT_OP","LEX_BEGIN","LEX_END","LEX_IF","LEX_ELSE","LEX_RETURN",
 "LEX_DELETE","LEX_WHILE","LEX_DO","LEX_FOR","LEX_BREAK","LEX_CONTINUE","LEX_PRINT",
@@ -294,7 +282,7 @@ static const char * const yytname[] = {   "$","error","$illegal.","FUNC_CALL",
 "print","if_statement","nls","opt_nls","input_redir","output_redir","opt_param_list",
 "param_list","opt_exp","opt_rexpression_list","rexpression_list","opt_expression_list",
 "expression_list","exp","@6","rexp","@7","simp_exp","non_post_simp_exp","opt_variable",
-"variable","l_brace","r_brace","r_paren","opt_semi","semi","comma",""
+"variable","l_brace","r_brace","r_paren","opt_semi","semi","comma", NULL
 };
 #endif
 
@@ -792,14 +780,15 @@ static const short yycheck[] = {     3,
     46,    47,    -1,    -1,    -1,    51,    -1,    -1,    54,    55
 };
 /* -*-C-*-  Note some compilers choke on comments on `#line' lines.  */
-#line 3 "/usr/local/lib/bison.simple"
+#line 3 "/usr/lib/bison.simple"
+/* This file comes from bison-1.28.  */
 
 /* Skeleton output parser for bison,
-   Copyright (C) 1984, 1989, 1990 Bob Corbett and Richard Stallman
+   Copyright (C) 1984, 1989, 1990 Free Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 1, or (at your option)
+   the Free Software Foundation; either version 2, or (at your option)
    any later version.
 
    This program is distributed in the hope that it will be useful,
@@ -809,42 +798,66 @@ static const short yycheck[] = {     3,
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
-   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+   Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
 
+/* As a special exception, when this file is copied by Bison into a
+   Bison output file, you may use that output file without restriction.
+   This special exception was added by the Free Software Foundation
+   in version 1.24 of Bison.  */
+
+/* This is the parser code that is written into each bison parser
+  when the %semantic_parser declaration is not specified in the grammar.
+  It was written by Richard Stallman by simplifying the hairy parser
+  used when %semantic_parser is specified.  */
 
-#ifndef alloca
+#ifndef YYSTACK_USE_ALLOCA
+#ifdef alloca
+#define YYSTACK_USE_ALLOCA
+#else /* alloca not defined */
 #ifdef __GNUC__
+#define YYSTACK_USE_ALLOCA
 #define alloca __builtin_alloca
 #else /* not GNU C.  */
-#if (!defined (__STDC__) && defined (sparc)) || defined (__sparc__) || defined (__sparc) || defined (__sgi)
+#if (!defined (__STDC__) && defined (sparc)) || defined (__sparc__) || defined (__sparc) || defined (__sgi) || (defined (__sun) && defined (__i386))
+#define YYSTACK_USE_ALLOCA
 #include <alloca.h>
 #else /* not sparc */
-#if defined (MSDOS) && !defined (__TURBOC__)
+/* We think this test detects Watcom and Microsoft C.  */
+/* This used to test MSDOS, but that is a bad idea
+   since that symbol is in the user namespace.  */
+#if (defined (_MSDOS) || defined (_MSDOS_)) && !defined (__TURBOC__)
+#if 0 /* No need for malloc.h, which pollutes the namespace;
+	 instead, just don't use alloca.  */
 #include <malloc.h>
+#endif
 #else /* not MSDOS, or __TURBOC__ */
 #if defined(_AIX)
-#include <malloc.h>
+/* I don't know what this was needed for, but it pollutes the namespace.
+   So I turned it off.   rms, 2 May 1997.  */
+/* #include <malloc.h>  */
  #pragma alloca
-#else /* not MSDOS, __TURBOC__, or _AIX */
-#ifdef __hpux
-#ifdef __cplusplus
-extern "C" {
-void *alloca (unsigned int);
-};
-#else /* not __cplusplus */
-void *alloca ();
-#endif /* not __cplusplus */
+#define YYSTACK_USE_ALLOCA
+#else /* not MSDOS, or __TURBOC__, or _AIX */
+#if 0
+#ifdef __hpux /* haible@ilog.fr says this works for HPUX 9.05 and up,
+		 and on HPUX 10.  Eventually we can turn this on.  */
+#define YYSTACK_USE_ALLOCA
+#define alloca __builtin_alloca
 #endif /* __hpux */
+#endif
 #endif /* not _AIX */
 #endif /* not MSDOS, or __TURBOC__ */
-#endif /* not sparc.  */
-#endif /* not GNU C.  */
-#endif /* alloca not defined.  */
+#endif /* not sparc */
+#endif /* not GNU C */
+#endif /* alloca not defined */
+#endif /* YYSTACK_USE_ALLOCA not defined */
 
-/* This is the parser code that is written into each bison parser
-  when the %semantic_parser declaration is not specified in the grammar.
-  It was written by Richard Stallman by simplifying the hairy parser
-  used when %semantic_parser is specified.  */
+#ifdef YYSTACK_USE_ALLOCA
+#define YYSTACK_ALLOC alloca
+#else
+#define YYSTACK_ALLOC malloc
+#endif
 
 /* Note: there must be only one dollar sign in this file.
    It is replaced by the list of actions, each action
@@ -854,8 +867,8 @@ void *alloca ();
 #define yyclearin	(yychar = YYEMPTY)
 #define YYEMPTY		-2
 #define YYEOF		0
-#define YYACCEPT	return(0)
-#define YYABORT 	return(1)
+#define YYACCEPT	goto yyacceptlab
+#define YYABORT 	goto yyabortlab
 #define YYERROR		goto yyerrlab1
 /* Like YYERROR except do call yyerror.
    This remains here temporarily to ease the
@@ -884,10 +897,18 @@ while (0)
 
 #ifdef YYPURE
 #ifdef YYLSP_NEEDED
+#ifdef YYLEX_PARAM
+#define YYLEX		yylex(&yylval, &yylloc, YYLEX_PARAM)
+#else
 #define YYLEX		yylex(&yylval, &yylloc)
+#endif
+#else /* not YYLSP_NEEDED */
+#ifdef YYLEX_PARAM
+#define YYLEX		yylex(&yylval, YYLEX_PARAM)
 #else
 #define YYLEX		yylex(&yylval)
 #endif
+#endif /* not YYLSP_NEEDED */
 #endif
 
 /* If nonreentrant, generate the variables here */
@@ -928,24 +949,24 @@ int yydebug;			/*  nonzero means print parse trace	*/
 #ifndef YYMAXDEPTH
 #define YYMAXDEPTH 10000
 #endif
-
-/* Prevent warning if -Wstrict-prototypes.  */
-#ifdef __GNUC__
-int yyparse (void);
-#endif
 
+/* Define __yy_memcpy.  Note that the size argument
+   should be passed with type unsigned int, because that is what the non-GCC
+   definitions require.  With GCC, __builtin_memcpy takes an arg
+   of type size_t, but it can handle unsigned int.  */
+
 #if __GNUC__ > 1		/* GNU C and GNU C++ define this.  */
-#define __yy_bcopy(FROM,TO,COUNT)	__builtin_memcpy(TO,FROM,COUNT)
+#define __yy_memcpy(TO,FROM,COUNT)	__builtin_memcpy(TO,FROM,COUNT)
 #else				/* not GNU C or C++ */
 #ifndef __cplusplus
 
 /* This is the most reliable way to avoid incompatibilities
    in available built-in functions on various systems.  */
 static void
-__yy_bcopy (from, to, count)
-     char *from;
+__yy_memcpy (to, from, count)
      char *to;
-     int count;
+     char *from;
+     unsigned int count;
 {
   register char *f = from;
   register char *t = to;
@@ -960,10 +981,10 @@ __yy_bcopy (from, to, count)
 /* This is the most reliable way to avoid incompatibilities
    in available built-in functions on various systems.  */
 static void
-__yy_bcopy (char *from, char *to, int count)
+__yy_memcpy (char *to, char *from, unsigned int count)
 {
-  register char *f = from;
   register char *t = to;
+  register char *f = from;
   register int i = count;
 
   while (i-- > 0)
@@ -973,9 +994,39 @@ __yy_bcopy (char *from, char *to, int count)
 #endif
 #endif
 
-#line 184 "/usr/local/lib/bison.simple"
+#line 217 "/usr/lib/bison.simple"
+
+/* The user can define YYPARSE_PARAM as the name of an argument to be passed
+   into yyparse.  The argument should have type void *.
+   It should actually point to an object.
+   Grammar actions can access the variable by casting it
+   to the proper pointer type.  */
+
+#ifdef YYPARSE_PARAM
+#ifdef __cplusplus
+#define YYPARSE_PARAM_ARG void *YYPARSE_PARAM
+#define YYPARSE_PARAM_DECL
+#else /* not __cplusplus */
+#define YYPARSE_PARAM_ARG YYPARSE_PARAM
+#define YYPARSE_PARAM_DECL void *YYPARSE_PARAM;
+#endif /* not __cplusplus */
+#else /* not YYPARSE_PARAM */
+#define YYPARSE_PARAM_ARG
+#define YYPARSE_PARAM_DECL
+#endif /* not YYPARSE_PARAM */
+
+/* Prevent warning if -Wstrict-prototypes.  */
+#ifdef __GNUC__
+#ifdef YYPARSE_PARAM
+int yyparse (void *);
+#else
+int yyparse (void);
+#endif
+#endif
+
 int
-yyparse()
+yyparse(YYPARSE_PARAM_ARG)
+     YYPARSE_PARAM_DECL
 {
   register int yystate;
   register int yyn;
@@ -1001,6 +1052,7 @@ yyparse()
 #endif
 
   int yystacksize = YYINITDEPTH;
+  int yyfree_stacks = 0;
 
 #ifdef YYPURE
   int yychar;
@@ -1085,18 +1137,32 @@ yynewstate:
       if (yystacksize >= YYMAXDEPTH)
 	{
 	  yyerror("parser stack overflow");
+	  if (yyfree_stacks)
+	    {
+	      free (yyss);
+	      free (yyvs);
+#ifdef YYLSP_NEEDED
+	      free (yyls);
+#endif
+	    }
 	  return 2;
 	}
       yystacksize *= 2;
       if (yystacksize > YYMAXDEPTH)
 	yystacksize = YYMAXDEPTH;
-      yyss = (short *) alloca (yystacksize * sizeof (*yyssp));
-      __yy_bcopy ((char *)yyss1, (char *)yyss, size * sizeof (*yyssp));
-      yyvs = (YYSTYPE *) alloca (yystacksize * sizeof (*yyvsp));
-      __yy_bcopy ((char *)yyvs1, (char *)yyvs, size * sizeof (*yyvsp));
+#ifndef YYSTACK_USE_ALLOCA
+      yyfree_stacks = 1;
+#endif
+      yyss = (short *) YYSTACK_ALLOC (yystacksize * sizeof (*yyssp));
+      __yy_memcpy ((char *)yyss, (char *)yyss1,
+		   size * (unsigned int) sizeof (*yyssp));
+      yyvs = (YYSTYPE *) YYSTACK_ALLOC (yystacksize * sizeof (*yyvsp));
+      __yy_memcpy ((char *)yyvs, (char *)yyvs1,
+		   size * (unsigned int) sizeof (*yyvsp));
 #ifdef YYLSP_NEEDED
-      yyls = (YYLTYPE *) alloca (yystacksize * sizeof (*yylsp));
-      __yy_bcopy ((char *)yyls1, (char *)yyls, size * sizeof (*yylsp));
+      yyls = (YYLTYPE *) YYSTACK_ALLOC (yystacksize * sizeof (*yylsp));
+      __yy_memcpy ((char *)yyls, (char *)yyls1,
+		   size * (unsigned int) sizeof (*yylsp));
 #endif
 #endif /* no yyoverflow */
 
@@ -1257,14 +1323,14 @@ yyreduce:
   switch (yyn) {
 
 case 1:
-#line 150 "./awk.y"
+#line 151 "./awk.y"
 {
 			expression_value = yyvsp[-1].nodeval;
 			check_funcs();
 		;
     break;}
 case 2:
-#line 158 "./awk.y"
+#line 159 "./awk.y"
 { 
 			if (yyvsp[0].nodeval != NULL)
 				yyval.nodeval = yyvsp[0].nodeval;
@@ -1274,7 +1340,7 @@ case 2:
 		;
     break;}
 case 3:
-#line 167 "./awk.y"
+#line 168 "./awk.y"
 {
 			if (yyvsp[0].nodeval == NULL)
 				yyval.nodeval = yyvsp[-1].nodeval;
@@ -1291,23 +1357,23 @@ case 3:
 		;
     break;}
 case 4:
-#line 181 "./awk.y"
+#line 182 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 5:
-#line 182 "./awk.y"
+#line 183 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 6:
-#line 183 "./awk.y"
+#line 184 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 7:
-#line 187 "./awk.y"
+#line 188 "./awk.y"
 { io_allowed = FALSE; ;
     break;}
 case 8:
-#line 189 "./awk.y"
+#line 190 "./awk.y"
 {
 		if (begin_block != NULL) {
 			if (begin_block->type != Node_rule_list)
@@ -1324,11 +1390,11 @@ case 8:
 	  ;
     break;}
 case 9:
-#line 203 "./awk.y"
+#line 204 "./awk.y"
 { io_allowed = FALSE; ;
     break;}
 case 10:
-#line 205 "./awk.y"
+#line 206 "./awk.y"
 {
 		if (end_block != NULL) {
 			if (end_block->type != Node_rule_list)
@@ -1345,7 +1411,7 @@ case 10:
 	  ;
     break;}
 case 11:
-#line 220 "./awk.y"
+#line 221 "./awk.y"
 {
 		warning("BEGIN blocks must have an action part");
 		errcount++;
@@ -1353,7 +1419,7 @@ case 11:
 	  ;
     break;}
 case 12:
-#line 226 "./awk.y"
+#line 227 "./awk.y"
 {
 		warning("END blocks must have an action part");
 		errcount++;
@@ -1361,15 +1427,15 @@ case 12:
 	  ;
     break;}
 case 13:
-#line 232 "./awk.y"
+#line 233 "./awk.y"
 { yyval.nodeval = node(yyvsp[-1].nodeval, Node_rule_node, yyvsp[0].nodeval); yyerrok; ;
     break;}
 case 14:
-#line 234 "./awk.y"
+#line 235 "./awk.y"
 { yyval.nodeval = node((NODE *) NULL, Node_rule_node, yyvsp[0].nodeval); yyerrok; ;
     break;}
 case 15:
-#line 236 "./awk.y"
+#line 237 "./awk.y"
 {
 		  yyval.nodeval = node(yyvsp[-1].nodeval,
 			     Node_rule_node,
@@ -1384,7 +1450,7 @@ case 15:
 		;
     break;}
 case 16:
-#line 249 "./awk.y"
+#line 250 "./awk.y"
 {
 			func_install(yyvsp[-1].nodeval, yyvsp[0].nodeval);
 			yyval.nodeval = NULL;
@@ -1392,15 +1458,15 @@ case 16:
 		;
     break;}
 case 17:
-#line 258 "./awk.y"
+#line 259 "./awk.y"
 { yyval.sval = yyvsp[0].sval; ;
     break;}
 case 18:
-#line 260 "./awk.y"
+#line 261 "./awk.y"
 { yyval.sval = yyvsp[0].sval; ;
     break;}
 case 19:
-#line 262 "./awk.y"
+#line 263 "./awk.y"
 {
 		yyerror("%s() is a built-in function, it cannot be redefined",
 			tokstart);
@@ -1409,15 +1475,19 @@ case 19:
 	  ;
     break;}
 case 22:
-#line 277 "./awk.y"
+#line 278 "./awk.y"
 {
 			param_counter = 0;
 		;
     break;}
 case 23:
-#line 281 "./awk.y"
+#line 282 "./awk.y"
 {
-			yyval.nodeval = append_right(make_param(yyvsp[-4].sval), yyvsp[-2].nodeval);
+			NODE *t;
+
+			t = make_param(yyvsp[-4].sval);
+			t->flags |= FUNC;
+			yyval.nodeval = append_right(t, yyvsp[-2].nodeval);
 			can_return = TRUE;
 			/* check for duplicate parameter names */
 			if (dup_parms(yyval.nodeval))
@@ -1425,33 +1495,33 @@ case 23:
 		;
     break;}
 case 24:
-#line 292 "./awk.y"
+#line 297 "./awk.y"
 {
 		yyval.nodeval = yyvsp[-2].nodeval;
 		can_return = FALSE;
 	  ;
     break;}
 case 25:
-#line 297 "./awk.y"
+#line 302 "./awk.y"
 {
 		yyval.nodeval = node((NODE *) NULL, Node_K_return, (NODE *) NULL);
 		can_return = FALSE;
 	  ;
     break;}
 case 26:
-#line 306 "./awk.y"
+#line 311 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 27:
-#line 308 "./awk.y"
+#line 313 "./awk.y"
 { yyval.nodeval = mkrangenode(node(yyvsp[-2].nodeval, Node_cond_pair, yyvsp[0].nodeval)); ;
     break;}
 case 28:
-#line 317 "./awk.y"
+#line 322 "./awk.y"
 { ++want_regexp; ;
     break;}
 case 29:
-#line 319 "./awk.y"
+#line 324 "./awk.y"
 {
 		  NODE *n;
 		  size_t len;
@@ -1468,15 +1538,15 @@ case 29:
 		;
     break;}
 case 30:
-#line 337 "./awk.y"
+#line 342 "./awk.y"
 { yyval.nodeval = yyvsp[-3].nodeval; ;
     break;}
 case 31:
-#line 339 "./awk.y"
+#line 344 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 32:
-#line 344 "./awk.y"
+#line 349 "./awk.y"
 {
 			yyval.nodeval = yyvsp[0].nodeval;
 			if (do_lint && isnoeffect(yyval.nodeval->type))
@@ -1484,7 +1554,7 @@ case 32:
 		;
     break;}
 case 33:
-#line 350 "./awk.y"
+#line 355 "./awk.y"
 {
 			if (yyvsp[-1].nodeval == NULL || yyvsp[-1].nodeval->type != Node_statement_list)
 				yyvsp[-1].nodeval = node(yyvsp[-1].nodeval, Node_statement_list, (NODE *) NULL);
@@ -1494,39 +1564,39 @@ case 33:
 		;
     break;}
 case 34:
-#line 358 "./awk.y"
+#line 363 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 35:
-#line 360 "./awk.y"
+#line 365 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 38:
-#line 370 "./awk.y"
+#line 375 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 39:
-#line 372 "./awk.y"
+#line 377 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 40:
-#line 374 "./awk.y"
+#line 379 "./awk.y"
 { yyval.nodeval = yyvsp[-1].nodeval; ;
     break;}
 case 41:
-#line 376 "./awk.y"
+#line 381 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 42:
-#line 378 "./awk.y"
+#line 383 "./awk.y"
 { yyval.nodeval = node(yyvsp[-3].nodeval, Node_K_while, yyvsp[0].nodeval); ;
     break;}
 case 43:
-#line 380 "./awk.y"
+#line 385 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_K_do, yyvsp[-5].nodeval); ;
     break;}
 case 44:
-#line 382 "./awk.y"
+#line 387 "./awk.y"
 {
 		yyval.nodeval = node(yyvsp[0].nodeval, Node_K_arrayfor,
 			make_for_loop(variable(yyvsp[-5].sval, CAN_FREE, Node_var),
@@ -1534,32 +1604,32 @@ case 44:
 	  ;
     break;}
 case 45:
-#line 388 "./awk.y"
+#line 393 "./awk.y"
 {
 		yyval.nodeval = node(yyvsp[0].nodeval, Node_K_for, (NODE *) make_for_loop(yyvsp[-7].nodeval, yyvsp[-5].nodeval, yyvsp[-3].nodeval));
 	  ;
     break;}
 case 46:
-#line 392 "./awk.y"
+#line 397 "./awk.y"
 {
 		yyval.nodeval = node(yyvsp[0].nodeval, Node_K_for,
 			(NODE *) make_for_loop(yyvsp[-6].nodeval, (NODE *) NULL, yyvsp[-3].nodeval));
 	  ;
     break;}
 case 47:
-#line 398 "./awk.y"
+#line 403 "./awk.y"
 { yyval.nodeval = node((NODE *) NULL, Node_K_break, (NODE *) NULL); ;
     break;}
 case 48:
-#line 401 "./awk.y"
+#line 406 "./awk.y"
 { yyval.nodeval = node((NODE *) NULL, Node_K_continue, (NODE *) NULL); ;
     break;}
 case 49:
-#line 403 "./awk.y"
+#line 408 "./awk.y"
 { yyval.nodeval = node(yyvsp[-3].nodeval, yyvsp[-5].nodetypeval, yyvsp[-1].nodeval); ;
     break;}
 case 50:
-#line 405 "./awk.y"
+#line 410 "./awk.y"
 {
 			if (yyvsp[-3].nodetypeval == Node_K_print && yyvsp[-2].nodeval == NULL) {
 				static int warned = FALSE;
@@ -1581,7 +1651,7 @@ case 50:
 		;
     break;}
 case 51:
-#line 425 "./awk.y"
+#line 430 "./awk.y"
 { NODETYPE type;
 
 		  if (yyvsp[-1].nodeval) {
@@ -1622,7 +1692,7 @@ case 51:
 		;
     break;}
 case 52:
-#line 464 "./awk.y"
+#line 469 "./awk.y"
 {
 		  if (do_lint)
 			warning("`nextfile' is a gawk extension");
@@ -1643,26 +1713,26 @@ case 52:
 		;
     break;}
 case 53:
-#line 483 "./awk.y"
+#line 488 "./awk.y"
 { yyval.nodeval = node(yyvsp[-1].nodeval, Node_K_exit, (NODE *) NULL); ;
     break;}
 case 54:
-#line 485 "./awk.y"
+#line 490 "./awk.y"
 {
 		  if (! can_return)
 			yyerror("`return' used outside function context");
 		;
     break;}
 case 55:
-#line 490 "./awk.y"
+#line 495 "./awk.y"
 { yyval.nodeval = node(yyvsp[-1].nodeval, Node_K_return, (NODE *) NULL); ;
     break;}
 case 56:
-#line 492 "./awk.y"
+#line 497 "./awk.y"
 { yyval.nodeval = node(variable(yyvsp[-4].sval, CAN_FREE, Node_var_array), Node_K_delete, yyvsp[-2].nodeval); ;
     break;}
 case 57:
-#line 494 "./awk.y"
+#line 499 "./awk.y"
 {
 		  if (do_lint)
 			warning("`delete array' is a gawk extension");
@@ -1678,107 +1748,107 @@ case 57:
 		;
     break;}
 case 58:
-#line 508 "./awk.y"
+#line 513 "./awk.y"
 { yyval.nodeval = yyvsp[-1].nodeval; ;
     break;}
 case 59:
-#line 513 "./awk.y"
+#line 518 "./awk.y"
 { yyval.nodetypeval = yyvsp[0].nodetypeval; ;
     break;}
 case 60:
-#line 515 "./awk.y"
+#line 520 "./awk.y"
 { yyval.nodetypeval = yyvsp[0].nodetypeval; ;
     break;}
 case 61:
-#line 520 "./awk.y"
+#line 525 "./awk.y"
 {
 		yyval.nodeval = node(yyvsp[-3].nodeval, Node_K_if, 
 			node(yyvsp[0].nodeval, Node_if_branches, (NODE *) NULL));
 	  ;
     break;}
 case 62:
-#line 526 "./awk.y"
+#line 531 "./awk.y"
 { yyval.nodeval = node(yyvsp[-6].nodeval, Node_K_if,
 				node(yyvsp[-3].nodeval, Node_if_branches, yyvsp[0].nodeval)); ;
     break;}
 case 63:
-#line 532 "./awk.y"
+#line 537 "./awk.y"
 { want_assign = FALSE; ;
     break;}
 case 67:
-#line 543 "./awk.y"
+#line 548 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 68:
-#line 545 "./awk.y"
+#line 550 "./awk.y"
 { yyval.nodeval = node(yyvsp[0].nodeval, Node_redirect_input, (NODE *) NULL); ;
     break;}
 case 69:
-#line 550 "./awk.y"
+#line 555 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 70:
-#line 552 "./awk.y"
+#line 557 "./awk.y"
 { yyval.nodeval = node(yyvsp[0].nodeval, Node_redirect_output, (NODE *) NULL); ;
     break;}
 case 71:
-#line 554 "./awk.y"
+#line 559 "./awk.y"
 { yyval.nodeval = node(yyvsp[0].nodeval, Node_redirect_append, (NODE *) NULL); ;
     break;}
 case 72:
-#line 556 "./awk.y"
+#line 561 "./awk.y"
 { yyval.nodeval = node(yyvsp[0].nodeval, Node_redirect_pipe, (NODE *) NULL); ;
     break;}
 case 73:
-#line 561 "./awk.y"
+#line 566 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 74:
-#line 563 "./awk.y"
+#line 568 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 75:
-#line 568 "./awk.y"
+#line 573 "./awk.y"
 { yyval.nodeval = make_param(yyvsp[0].sval); ;
     break;}
 case 76:
-#line 570 "./awk.y"
+#line 575 "./awk.y"
 { yyval.nodeval = append_right(yyvsp[-2].nodeval, make_param(yyvsp[0].sval)); yyerrok; ;
     break;}
 case 77:
-#line 572 "./awk.y"
+#line 577 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 78:
-#line 574 "./awk.y"
+#line 579 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 79:
-#line 576 "./awk.y"
+#line 581 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 80:
-#line 582 "./awk.y"
+#line 587 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 81:
-#line 584 "./awk.y"
+#line 589 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 82:
-#line 589 "./awk.y"
+#line 594 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 83:
-#line 591 "./awk.y"
+#line 596 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 84:
-#line 596 "./awk.y"
+#line 601 "./awk.y"
 { yyval.nodeval = node(yyvsp[0].nodeval, Node_expression_list, (NODE *) NULL); ;
     break;}
 case 85:
-#line 598 "./awk.y"
+#line 603 "./awk.y"
 {
 		yyval.nodeval = append_right(yyvsp[-2].nodeval,
 			node(yyvsp[0].nodeval, Node_expression_list, (NODE *) NULL));
@@ -1786,35 +1856,35 @@ case 85:
 	  ;
     break;}
 case 86:
-#line 604 "./awk.y"
+#line 609 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 87:
-#line 606 "./awk.y"
+#line 611 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 88:
-#line 608 "./awk.y"
+#line 613 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 89:
-#line 610 "./awk.y"
+#line 615 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 90:
-#line 615 "./awk.y"
+#line 620 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 91:
-#line 617 "./awk.y"
+#line 622 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 92:
-#line 622 "./awk.y"
+#line 627 "./awk.y"
 { yyval.nodeval = node(yyvsp[0].nodeval, Node_expression_list, (NODE *) NULL); ;
     break;}
 case 93:
-#line 624 "./awk.y"
+#line 629 "./awk.y"
 {
 			yyval.nodeval = append_right(yyvsp[-2].nodeval,
 				node(yyvsp[0].nodeval, Node_expression_list, (NODE *) NULL));
@@ -1822,27 +1892,27 @@ case 93:
 		;
     break;}
 case 94:
-#line 630 "./awk.y"
+#line 635 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 95:
-#line 632 "./awk.y"
+#line 637 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 96:
-#line 634 "./awk.y"
+#line 639 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 97:
-#line 636 "./awk.y"
+#line 641 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 98:
-#line 641 "./awk.y"
+#line 646 "./awk.y"
 { want_assign = FALSE; ;
     break;}
 case 99:
-#line 643 "./awk.y"
+#line 648 "./awk.y"
 {
 		  if (do_lint && yyvsp[0].nodeval->type == Node_regex)
 			warning("Regular expression on left of assignment.");
@@ -1850,18 +1920,18 @@ case 99:
 		;
     break;}
 case 100:
-#line 649 "./awk.y"
+#line 654 "./awk.y"
 { yyval.nodeval = node(variable(yyvsp[0].sval, CAN_FREE, Node_var_array), Node_in_array, yyvsp[-3].nodeval); ;
     break;}
 case 101:
-#line 651 "./awk.y"
+#line 656 "./awk.y"
 {
 		  yyval.nodeval = node(yyvsp[0].nodeval, Node_K_getline,
 			 node(yyvsp[-3].nodeval, Node_redirect_pipein, (NODE *) NULL));
 		;
     break;}
 case 102:
-#line 656 "./awk.y"
+#line 661 "./awk.y"
 {
 		  if (do_lint && ! io_allowed && yyvsp[0].nodeval == NULL)
 			warning("non-redirected getline undefined inside BEGIN or END action");
@@ -1869,15 +1939,15 @@ case 102:
 		;
     break;}
 case 103:
-#line 662 "./awk.y"
+#line 667 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_and, yyvsp[0].nodeval); ;
     break;}
 case 104:
-#line 664 "./awk.y"
+#line 669 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_or, yyvsp[0].nodeval); ;
     break;}
 case 105:
-#line 666 "./awk.y"
+#line 671 "./awk.y"
 {
 		  if (yyvsp[-2].nodeval->type == Node_regex)
 			warning("Regular expression on left of MATCH operator.");
@@ -1885,7 +1955,7 @@ case 105:
 		;
     break;}
 case 106:
-#line 672 "./awk.y"
+#line 677 "./awk.y"
 {
 		  yyval.nodeval = yyvsp[0].nodeval;
 		  if (do_lint && tokstart[0] == '*') {
@@ -1897,7 +1967,7 @@ case 106:
 		;
     break;}
 case 107:
-#line 682 "./awk.y"
+#line 687 "./awk.y"
 {
 		  yyval.nodeval = node(node(make_number(0.0),
 				 Node_field_spec,
@@ -1907,11 +1977,11 @@ case 107:
 		;
     break;}
 case 108:
-#line 690 "./awk.y"
+#line 695 "./awk.y"
 { yyval.nodeval = node(variable(yyvsp[0].sval, CAN_FREE, Node_var_array), Node_in_array, yyvsp[-2].nodeval); ;
     break;}
 case 109:
-#line 692 "./awk.y"
+#line 697 "./awk.y"
 {
 		  if (do_lint && yyvsp[0].nodeval->type == Node_regex)
 			warning("Regular expression on left of comparison.");
@@ -1919,43 +1989,43 @@ case 109:
 		;
     break;}
 case 110:
-#line 698 "./awk.y"
+#line 703 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_less, yyvsp[0].nodeval); ;
     break;}
 case 111:
-#line 700 "./awk.y"
+#line 705 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_greater, yyvsp[0].nodeval); ;
     break;}
 case 112:
-#line 702 "./awk.y"
+#line 707 "./awk.y"
 { yyval.nodeval = node(yyvsp[-4].nodeval, Node_cond_exp, node(yyvsp[-2].nodeval, Node_if_branches, yyvsp[0].nodeval));;
     break;}
 case 113:
-#line 704 "./awk.y"
+#line 709 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 114:
-#line 706 "./awk.y"
+#line 711 "./awk.y"
 { yyval.nodeval = node(yyvsp[-1].nodeval, Node_concat, yyvsp[0].nodeval); ;
     break;}
 case 115:
-#line 711 "./awk.y"
+#line 716 "./awk.y"
 { want_assign = FALSE; ;
     break;}
 case 116:
-#line 713 "./awk.y"
+#line 718 "./awk.y"
 { yyval.nodeval = node(yyvsp[-3].nodeval, yyvsp[-2].nodetypeval, yyvsp[0].nodeval); ;
     break;}
 case 117:
-#line 715 "./awk.y"
+#line 720 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_and, yyvsp[0].nodeval); ;
     break;}
 case 118:
-#line 717 "./awk.y"
+#line 722 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_or, yyvsp[0].nodeval); ;
     break;}
 case 119:
-#line 719 "./awk.y"
+#line 724 "./awk.y"
 {
 		  if (do_lint && ! io_allowed && yyvsp[0].nodeval == NULL)
 			warning("non-redirected getline undefined inside BEGIN or END action");
@@ -1963,87 +2033,87 @@ case 119:
 		;
     break;}
 case 120:
-#line 725 "./awk.y"
+#line 730 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 121:
-#line 727 "./awk.y"
+#line 732 "./awk.y"
 { yyval.nodeval = node((NODE *) NULL, Node_nomatch, yyvsp[0].nodeval); ;
     break;}
 case 122:
-#line 729 "./awk.y"
+#line 734 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, yyvsp[-1].nodetypeval, mk_rexp(yyvsp[0].nodeval)); ;
     break;}
 case 123:
-#line 731 "./awk.y"
+#line 736 "./awk.y"
 { yyval.nodeval = node(variable(yyvsp[0].sval, CAN_FREE, Node_var_array), Node_in_array, yyvsp[-2].nodeval); ;
     break;}
 case 124:
-#line 733 "./awk.y"
+#line 738 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, yyvsp[-1].nodetypeval, yyvsp[0].nodeval); ;
     break;}
 case 125:
-#line 735 "./awk.y"
+#line 740 "./awk.y"
 { yyval.nodeval = node(yyvsp[-4].nodeval, Node_cond_exp, node(yyvsp[-2].nodeval, Node_if_branches, yyvsp[0].nodeval));;
     break;}
 case 126:
-#line 737 "./awk.y"
+#line 742 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 127:
-#line 739 "./awk.y"
+#line 744 "./awk.y"
 { yyval.nodeval = node(yyvsp[-1].nodeval, Node_concat, yyvsp[0].nodeval); ;
     break;}
 case 129:
-#line 746 "./awk.y"
+#line 751 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_exp, yyvsp[0].nodeval); ;
     break;}
 case 130:
-#line 748 "./awk.y"
+#line 753 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_times, yyvsp[0].nodeval); ;
     break;}
 case 131:
-#line 750 "./awk.y"
+#line 755 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_quotient, yyvsp[0].nodeval); ;
     break;}
 case 132:
-#line 752 "./awk.y"
+#line 757 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_mod, yyvsp[0].nodeval); ;
     break;}
 case 133:
-#line 754 "./awk.y"
+#line 759 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_plus, yyvsp[0].nodeval); ;
     break;}
 case 134:
-#line 756 "./awk.y"
+#line 761 "./awk.y"
 { yyval.nodeval = node(yyvsp[-2].nodeval, Node_minus, yyvsp[0].nodeval); ;
     break;}
 case 135:
-#line 758 "./awk.y"
+#line 763 "./awk.y"
 { yyval.nodeval = node(yyvsp[-1].nodeval, Node_postincrement, (NODE *) NULL); ;
     break;}
 case 136:
-#line 760 "./awk.y"
+#line 765 "./awk.y"
 { yyval.nodeval = node(yyvsp[-1].nodeval, Node_postdecrement, (NODE *) NULL); ;
     break;}
 case 137:
-#line 765 "./awk.y"
+#line 770 "./awk.y"
 { yyval.nodeval = node(yyvsp[0].nodeval, Node_not, (NODE *) NULL); ;
     break;}
 case 138:
-#line 767 "./awk.y"
+#line 772 "./awk.y"
 { yyval.nodeval = yyvsp[-1].nodeval; ;
     break;}
 case 139:
-#line 770 "./awk.y"
+#line 775 "./awk.y"
 { yyval.nodeval = snode(yyvsp[-1].nodeval, Node_builtin, (int) yyvsp[-3].lval); ;
     break;}
 case 140:
-#line 772 "./awk.y"
+#line 777 "./awk.y"
 { yyval.nodeval = snode(yyvsp[-1].nodeval, Node_builtin, (int) yyvsp[-3].lval); ;
     break;}
 case 141:
-#line 774 "./awk.y"
+#line 779 "./awk.y"
 {
 		if (do_lint)
 			warning("call of `length' without parentheses is not portable");
@@ -2053,7 +2123,7 @@ case 141:
 	  ;
     break;}
 case 142:
-#line 782 "./awk.y"
+#line 787 "./awk.y"
 {
 		yyval.nodeval = node(yyvsp[-1].nodeval, Node_func_call, make_string(yyvsp[-3].sval, strlen(yyvsp[-3].sval)));
 		func_use(yyvsp[-3].sval, FUNC_USE);
@@ -2062,23 +2132,23 @@ case 142:
 	  ;
     break;}
 case 144:
-#line 790 "./awk.y"
+#line 795 "./awk.y"
 { yyval.nodeval = node(yyvsp[0].nodeval, Node_preincrement, (NODE *) NULL); ;
     break;}
 case 145:
-#line 792 "./awk.y"
+#line 797 "./awk.y"
 { yyval.nodeval = node(yyvsp[0].nodeval, Node_predecrement, (NODE *) NULL); ;
     break;}
 case 146:
-#line 794 "./awk.y"
+#line 799 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 147:
-#line 796 "./awk.y"
+#line 801 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 148:
-#line 799 "./awk.y"
+#line 804 "./awk.y"
 {
 		  if (yyvsp[0].nodeval->type == Node_val) {
 			yyvsp[0].nodeval->numbr = -(force_number(yyvsp[0].nodeval));
@@ -2088,7 +2158,7 @@ case 148:
 		;
     break;}
 case 149:
-#line 807 "./awk.y"
+#line 812 "./awk.y"
 {
 		  /*
 		   * was: $$ = $2
@@ -2098,19 +2168,19 @@ case 149:
 		;
     break;}
 case 150:
-#line 818 "./awk.y"
+#line 823 "./awk.y"
 { yyval.nodeval = NULL; ;
     break;}
 case 151:
-#line 820 "./awk.y"
+#line 825 "./awk.y"
 { yyval.nodeval = yyvsp[0].nodeval; ;
     break;}
 case 152:
-#line 825 "./awk.y"
+#line 830 "./awk.y"
 { yyval.nodeval = variable(yyvsp[0].sval, CAN_FREE, Node_var); ;
     break;}
 case 153:
-#line 827 "./awk.y"
+#line 832 "./awk.y"
 {
 		if (yyvsp[-1].nodeval->rnode == NULL) {
 			yyval.nodeval = node(variable(yyvsp[-3].sval, CAN_FREE, Node_var_array), Node_subscript, yyvsp[-1].nodeval->lnode);
@@ -2120,28 +2190,28 @@ case 153:
 		;
     break;}
 case 154:
-#line 835 "./awk.y"
+#line 840 "./awk.y"
 { yyval.nodeval = node(yyvsp[0].nodeval, Node_field_spec, (NODE *) NULL); ;
     break;}
 case 156:
-#line 843 "./awk.y"
+#line 848 "./awk.y"
 { yyerrok; ;
     break;}
 case 157:
-#line 847 "./awk.y"
+#line 852 "./awk.y"
 { yyerrok; ;
     break;}
 case 160:
-#line 856 "./awk.y"
+#line 861 "./awk.y"
 { yyerrok; want_assign = FALSE; ;
     break;}
 case 161:
-#line 859 "./awk.y"
+#line 864 "./awk.y"
 { yyerrok; ;
     break;}
 }
    /* the action file gets copied in in place of this dollarsign */
-#line 465 "/usr/local/lib/bison.simple"
+#line 543 "/usr/lib/bison.simple"
 
   yyvsp -= yylen;
   yyssp -= yylen;
@@ -2336,8 +2406,32 @@ yyerrhandle:
 
   yystate = yyn;
   goto yynewstate;
+
+ yyacceptlab:
+  /* YYACCEPT comes here.  */
+  if (yyfree_stacks)
+    {
+      free (yyss);
+      free (yyvs);
+#ifdef YYLSP_NEEDED
+      free (yyls);
+#endif
+    }
+  return 0;
+
+ yyabortlab:
+  /* YYABORT comes here.  */
+  if (yyfree_stacks)
+    {
+      free (yyss);
+      free (yyvs);
+#ifdef YYLSP_NEEDED
+      free (yyls);
+#endif
+    }
+  return 1;
 }
-#line 862 "./awk.y"
+#line 867 "./awk.y"
 
 
 struct token {
@@ -2481,7 +2575,6 @@ va_dcl
 	strcpy(bp, mesg);
 	err("", buf, args);
 	va_end(args);
-	exit(2);
 }
 
 /* get_src_buf --- read the next buffer of source program */
@@ -3323,6 +3416,11 @@ NODE *subn;
 	r->proc = tokentab[idx].ptr;
 
 	/* special case processing for a few builtins */
+	/*
+	 * FIXME: go through these to make sure that everything done
+	 *	  here is really right. Move anything that's not into
+	 *	  the corresponding routine.
+	 */
 	if (nexp == 0 && r->proc == do_length) {
 		subn = node(node(make_number(0.0), Node_field_spec, (NODE *) NULL),
 		            Node_expression_list,
@@ -3339,8 +3437,12 @@ NODE *subn;
 						     (NODE *) NULL),
 					        Node_expression_list,
 						(NODE *) NULL));
-		else if (do_lint && subn->rnode->rnode->lnode->type == Node_val)
-			warning("string literal as last arg of substitute");
+		else if (subn->rnode->rnode->lnode->type == Node_val) {
+			if (do_lint)
+				warning("string literal as last arg of substitute");
+		} else if (! isassignable(subn->rnode->rnode->lnode))
+			yyerror("%s third parameter is not a changeable object",
+				r->proc == do_sub ? "sub" : "gsub");
 	} else if (r->proc == do_gensub) {
 		if (subn->lnode->type != Node_regex)
 			subn->lnode = mk_rexp(subn->lnode);
@@ -3797,3 +3899,33 @@ NODETYPE type;
 
 	return FALSE;
 }
+
+/* isassignable --- can this node be assigned to? */
+
+static int
+isassignable(n)
+register NODE *n;
+{
+	switch (n->type) {
+	case Node_var:
+	case Node_FIELDWIDTHS:
+	case Node_RS:
+	case Node_FS:
+	case Node_FNR:
+	case Node_NR:
+	case Node_NF:
+	case Node_IGNORECASE:
+	case Node_OFMT:
+	case Node_CONVFMT:
+	case Node_ORS:
+	case Node_OFS:
+	case Node_field_spec:
+	case Node_subscript:
+		return TRUE;
+	case Node_param_list:
+		return ((n->flags & FUNC) == 0);  /* ok if not func name */
+	default:
+		break;	/* keeps gcc -Wall happy */
+	}
+	return FALSE;
+}
diff --git a/builtin.c b/builtin.c
index b8fc58ff..35402f1e 100644
--- a/builtin.c
+++ b/builtin.c
@@ -926,9 +926,11 @@ NODE *tree;
 	char buf[BUFSIZ];
 	static char def_format[] = "%a %b %d %H:%M:%S %Z %Y";
 	char *format;
+	int formatlen;
 
 	/* set defaults first */
 	format = def_format;	/* traditional date format */
+	formatlen = strlen(format);
 	(void) time(&fclock);	/* current time of day */
 
 	t1 = t2 = NULL;
@@ -936,8 +938,13 @@ NODE *tree;
 		if (tree->lnode != NULL) {
 			t1 = force_string(tree_eval(tree->lnode));
 			format = t1->stptr;
-			if (do_lint && t1->stlen == 0)
-				warning("strftime called with empty format string");
+			formatlen = t1->stlen;
+			if (formatlen == 0) {
+				if (do_lint)
+					warning("strftime called with empty format string");
+				free_temp(t1);
+				return tmp_string("", 0);
+			}
 		}
 	
 		if (tree->rnode != NULL) {
@@ -953,7 +960,15 @@ NODE *tree;
 	bufsize = sizeof(buf);
 	for (;;) {
 		buflen = strftime(bufp, bufsize, format, tm);
-		if (buflen > 0)
+		/*
+		 * buflen can be zero EITHER because there's not enough
+		 * room in the string, or because the control command
+		 * goes to the empty string. Make a reasonable guess that
+		 * if the buffer is 4 times bigger than the length of the
+		 * format string, it's not failing for lack of room.
+		 * Thanks to Paul Eggert for pointing out this issue.
+		 */
+		if (buflen > 0 || bufsize >= 4 * formatlen)
 			break;
 		bufsize *= 2;
 		if (bufp == buf)
@@ -981,6 +996,8 @@ NODE *tree;
 	return tmp_number((AWKNUM) lclock);
 }
 
+
+
 /* do_system --- run an external command */
 
 NODE *
diff --git a/configh.in b/configh.in
index 33c1371e..4c197f3b 100644
--- a/configh.in
+++ b/configh.in
@@ -107,9 +107,9 @@
 /* If using the C implementation of alloca, define if you know the
    direction of stack growth for your system; otherwise it will be
    automatically deduced at run-time.
-	STACK_DIRECTION > 0 => grows toward higher addresses
-	STACK_DIRECTION < 0 => grows toward lower addresses
-	STACK_DIRECTION = 0 => direction of growth unknown
+ STACK_DIRECTION > 0 => grows toward higher addresses
+ STACK_DIRECTION < 0 => grows toward lower addresses
+ STACK_DIRECTION = 0 => direction of growth unknown
  */
 #undef STACK_DIRECTION
 
@@ -125,9 +125,9 @@
 /* Define to `int' if <sys/types.h> doesn't define.  */
 #undef uid_t
 
-#undef HAVE_STRINGIZE	/* can use ANSI # operator in cpp */
-#undef REGEX_MALLOC	/* use malloc instead of alloca in regex.c */
-#undef SPRINTF_RET	/* return type of sprintf */
+#undef HAVE_STRINGIZE /* can use ANSI # operator in cpp */
+#undef REGEX_MALLOC /* use malloc instead of alloca in regex.c */
+#undef SPRINTF_RET /* return type of sprintf */
 
 /* Define if you have the fmod function.  */
 #undef HAVE_FMOD
@@ -171,9 +171,6 @@
 /* Define if you have the tzset function.  */
 #undef HAVE_TZSET
 
-/* Define if you have the valloc function.  */
-#undef HAVE_VALLOC
-
 /* Define if you have the <limits.h> header file.  */
 #undef HAVE_LIMITS_H
 
diff --git a/configure b/configure
index 57c7250c..0d0b776c 100755
--- a/configure
+++ b/configure
@@ -1,8 +1,8 @@
 #! /bin/sh
 
 # Guess values for system-dependent variables and create Makefiles.
-# Generated automatically using autoconf version 2.7 
-# Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
+# Generated automatically using autoconf version 2.12 
+# Copyright (C) 1992, 93, 94, 95, 96 Free Software Foundation, Inc.
 #
 # This configure script is free software; the Free Software Foundation
 # gives unlimited permission to copy, distribute and modify it.
@@ -49,6 +49,8 @@ mandir='${prefix}/man'
 # Initialize some other variables.
 subdirs=
 MFLAGS= MAKEFLAGS=
+# Maximum number of lines to put in a shell here document.
+ac_max_here_lines=12
 
 ac_prev=
 for ac_option
@@ -330,7 +332,7 @@ EOF
     verbose=yes ;;
 
   -version | --version | --versio | --versi | --vers)
-    echo "configure generated by autoconf version 2.7"
+    echo "configure generated by autoconf version 2.12"
     exit 0 ;;
 
   -with-* | --with-*)
@@ -432,11 +434,14 @@ do
 done
 
 # NLS nuisances.
-# Only set LANG and LC_ALL to C if already set.
-# These must not be set unconditionally because not all systems understand
-# e.g. LANG=C (notably SCO).
-if test "${LC_ALL+set}" = set; then LC_ALL=C; export LC_ALL; fi
+# Only set these to C if already set.  These must not be set unconditionally
+# because not all systems understand e.g. LANG=C (notably SCO).
+# Fixing LC_MESSAGES prevents Solaris sh from translating var values in `set'!
+# Non-C LC_CTYPE values break the ctype check.
 if test "${LANG+set}"   = set; then LANG=C;   export LANG;   fi
+if test "${LC_ALL+set}" = set; then LC_ALL=C; export LC_ALL; fi
+if test "${LC_MESSAGES+set}" = set; then LC_MESSAGES=C; export LC_MESSAGES; fi
+if test "${LC_CTYPE+set}"    = set; then LC_CTYPE=C;    export LC_CTYPE;    fi
 
 # confdefs.h avoids OS command line length limits that DEFS can exceed.
 rm -rf conftest* confdefs.h
@@ -495,12 +500,10 @@ fi
 
 ac_ext=c
 # CFLAGS is not in ac_cpp because -g, -O, etc. are not valid cpp options.
-ac_cpp='echo $CPP $CPPFLAGS 1>&5;
-$CPP $CPPFLAGS'
-ac_compile='echo ${CC-cc} -c $CFLAGS $CPPFLAGS conftest.$ac_ext 1>&5;
-${CC-cc} -c $CFLAGS $CPPFLAGS conftest.$ac_ext 1>&5 2>&5'
-ac_link='echo ${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS 1>&5;
-${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS 1>&5 2>&5'
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='${CC-cc} -c $CFLAGS $CPPFLAGS conftest.$ac_ext 1>&5'
+ac_link='${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS 1>&5'
+cross_compiling=$ac_cv_prog_cc_cross
 
 if (echo "testing\c"; echo 1,2,3) | grep c >/dev/null; then
   # Stardent Vistra SVR4 grep lacks -e, says ghazi@caip.rutgers.edu.
@@ -523,6 +526,7 @@ do
 # Extract the first word of "$ac_prog", so it can be a program name with args.
 set dummy $ac_prog; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
+echo "configure:530: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_YACC'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -552,6 +556,7 @@ done
 test -n "$YACC" || YACC="yacc"
 
 echo $ac_n "checking whether ln -s works""... $ac_c" 1>&6
+echo "configure:560: checking whether ln -s works" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_LN_S'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -574,6 +579,7 @@ fi
 # Extract the first word of "gcc", so it can be a program name with args.
 set dummy gcc; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
+echo "configure:583: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_CC'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -589,7 +595,6 @@ else
     fi
   done
   IFS="$ac_save_ifs"
-  test -z "$ac_cv_prog_CC" && ac_cv_prog_CC="cc"
 fi
 fi
 CC="$ac_cv_prog_CC"
@@ -599,8 +604,98 @@ else
   echo "$ac_t""no" 1>&6
 fi
 
+if test -z "$CC"; then
+  # Extract the first word of "cc", so it can be a program name with args.
+set dummy cc; ac_word=$2
+echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
+echo "configure:612: checking for $ac_word" >&5
+if eval "test \"`echo '$''{'ac_cv_prog_CC'+set}'`\" = set"; then
+  echo $ac_n "(cached) $ac_c" 1>&6
+else
+  if test -n "$CC"; then
+  ac_cv_prog_CC="$CC" # Let the user override the test.
+else
+  IFS="${IFS= 	}"; ac_save_ifs="$IFS"; IFS="${IFS}:"
+  ac_prog_rejected=no
+  for ac_dir in $PATH; do
+    test -z "$ac_dir" && ac_dir=.
+    if test -f $ac_dir/$ac_word; then
+      if test "$ac_dir/$ac_word" = "/usr/ucb/cc"; then
+        ac_prog_rejected=yes
+	continue
+      fi
+      ac_cv_prog_CC="cc"
+      break
+    fi
+  done
+  IFS="$ac_save_ifs"
+if test $ac_prog_rejected = yes; then
+  # We found a bogon in the path, so make sure we never use it.
+  set dummy $ac_cv_prog_CC
+  shift
+  if test $# -gt 0; then
+    # We chose a different compiler from the bogus one.
+    # However, it has the same basename, so the bogon will be chosen
+    # first if we set CC to just the basename; use the full file name.
+    shift
+    set dummy "$ac_dir/$ac_word" "$@"
+    shift
+    ac_cv_prog_CC="$@"
+  fi
+fi
+fi
+fi
+CC="$ac_cv_prog_CC"
+if test -n "$CC"; then
+  echo "$ac_t""$CC" 1>&6
+else
+  echo "$ac_t""no" 1>&6
+fi
+
+  test -z "$CC" && { echo "configure: error: no acceptable cc found in \$PATH" 1>&2; exit 1; }
+fi
+
+echo $ac_n "checking whether the C compiler ($CC $CFLAGS $LDFLAGS) works""... $ac_c" 1>&6
+echo "configure:660: checking whether the C compiler ($CC $CFLAGS $LDFLAGS) works" >&5
+
+ac_ext=c
+# CFLAGS is not in ac_cpp because -g, -O, etc. are not valid cpp options.
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='${CC-cc} -c $CFLAGS $CPPFLAGS conftest.$ac_ext 1>&5'
+ac_link='${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS 1>&5'
+cross_compiling=$ac_cv_prog_cc_cross
+
+cat > conftest.$ac_ext <<EOF
+#line 670 "configure"
+#include "confdefs.h"
+main(){return(0);}
+EOF
+if { (eval echo configure:674: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
+  ac_cv_prog_cc_works=yes
+  # If we can't run a trivial program, we are probably using a cross compiler.
+  if (./conftest; exit) 2>/dev/null; then
+    ac_cv_prog_cc_cross=no
+  else
+    ac_cv_prog_cc_cross=yes
+  fi
+else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  ac_cv_prog_cc_works=no
+fi
+rm -fr conftest*
+
+echo "$ac_t""$ac_cv_prog_cc_works" 1>&6
+if test $ac_cv_prog_cc_works = no; then
+  { echo "configure: error: installation or configuration problem: C compiler cannot create executables." 1>&2; exit 1; }
+fi
+echo $ac_n "checking whether the C compiler ($CC $CFLAGS $LDFLAGS) is a cross-compiler""... $ac_c" 1>&6
+echo "configure:694: checking whether the C compiler ($CC $CFLAGS $LDFLAGS) is a cross-compiler" >&5
+echo "$ac_t""$ac_cv_prog_cc_cross" 1>&6
+cross_compiling=$ac_cv_prog_cc_cross
 
 echo $ac_n "checking whether we are using GNU C""... $ac_c" 1>&6
+echo "configure:699: checking whether we are using GNU C" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_gcc'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -609,7 +704,7 @@ else
   yes;
 #endif
 EOF
-if ${CC-cc} -E conftest.c 2>&5 | egrep yes >/dev/null 2>&1; then
+if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:708: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
   ac_cv_prog_gcc=yes
 else
   ac_cv_prog_gcc=no
@@ -617,29 +712,34 @@ fi
 fi
 
 echo "$ac_t""$ac_cv_prog_gcc" 1>&6
+
 if test $ac_cv_prog_gcc = yes; then
   GCC=yes
-  if test "${CFLAGS+set}" != set; then
-    echo $ac_n "checking whether ${CC-cc} accepts -g""... $ac_c" 1>&6
-if eval "test \"`echo '$''{'ac_cv_prog_gcc_g'+set}'`\" = set"; then
+  ac_test_CFLAGS="${CFLAGS+set}"
+  ac_save_CFLAGS="$CFLAGS"
+  CFLAGS=
+  echo $ac_n "checking whether ${CC-cc} accepts -g""... $ac_c" 1>&6
+echo "configure:723: checking whether ${CC-cc} accepts -g" >&5
+if eval "test \"`echo '$''{'ac_cv_prog_cc_g'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   echo 'void f(){}' > conftest.c
 if test -z "`${CC-cc} -g -c conftest.c 2>&1`"; then
-  ac_cv_prog_gcc_g=yes
+  ac_cv_prog_cc_g=yes
 else
-  ac_cv_prog_gcc_g=no
+  ac_cv_prog_cc_g=no
 fi
 rm -f conftest*
 
 fi
 
-echo "$ac_t""$ac_cv_prog_gcc_g" 1>&6
-    if test $ac_cv_prog_gcc_g = yes; then
-      CFLAGS="-g -O"
-    else
-      CFLAGS="-O"
-    fi
+echo "$ac_t""$ac_cv_prog_cc_g" 1>&6
+  if test "$ac_test_CFLAGS" = set; then
+    CFLAGS="$ac_save_CFLAGS"
+  elif test $ac_cv_prog_cc_g = yes; then
+    CFLAGS="-g -O2"
+  else
+    CFLAGS="-O2"
   fi
 else
   GCC=
@@ -647,6 +747,7 @@ else
 fi
 
 echo $ac_n "checking how to run the C preprocessor""... $ac_c" 1>&6
+echo "configure:751: checking how to run the C preprocessor" >&5
 # On Suns, sometimes $CPP names a directory.
 if test -n "$CPP" && test -d "$CPP"; then
   CPP=
@@ -661,31 +762,37 @@ else
   # On the NeXT, cc -E runs the code through the compiler's parser,
   # not just through cpp.
   cat > conftest.$ac_ext <<EOF
-#line 665 "configure"
+#line 766 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:772: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   :
 else
   echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   CPP="${CC-cc} -E -traditional-cpp"
   cat > conftest.$ac_ext <<EOF
-#line 679 "configure"
+#line 783 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:789: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   :
 else
   echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   CPP=/lib/cpp
 fi
@@ -734,11 +841,12 @@ ac_configure=$ac_aux_dir/configure # This should be Cygnus configure.
 # SVR4 /usr/ucb/install, which tries to use the nonexistent group "staff"
 # ./install, which can be erroneously created by make from ./install.sh.
 echo $ac_n "checking for a BSD compatible install""... $ac_c" 1>&6
+echo "configure:845: checking for a BSD compatible install" >&5
 if test -z "$INSTALL"; then
 if eval "test \"`echo '$''{'ac_cv_path_install'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
-    IFS="${IFS= 	}"; ac_save_ifs="$IFS"; IFS="${IFS}:"
+    IFS="${IFS= 	}"; ac_save_IFS="$IFS"; IFS="${IFS}:"
   for ac_dir in $PATH; do
     # Account for people who put trailing slashes in PATH elements.
     case "$ac_dir/" in
@@ -761,7 +869,7 @@ else
       ;;
     esac
   done
-  IFS="$ac_save_ifs"
+  IFS="$ac_save_IFS"
 
 fi
   if test "${ac_cv_path_install+set}" = set; then
@@ -784,7 +892,8 @@ test -z "$INSTALL_DATA" && INSTALL_DATA='${INSTALL} -m 644'
 
 
 echo $ac_n "checking whether ${MAKE-make} sets \${MAKE}""... $ac_c" 1>&6
-set dummy ${MAKE-make}; ac_make=$2
+echo "configure:896: checking whether ${MAKE-make} sets \${MAKE}" >&5
+set dummy ${MAKE-make}; ac_make=`echo "$2" | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_prog_make_${ac_make}_set'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -822,8 +931,9 @@ fi
 
 
 echo $ac_n "checking for AIX""... $ac_c" 1>&6
+echo "configure:935: checking for AIX" >&5
 cat > conftest.$ac_ext <<EOF
-#line 827 "configure"
+#line 937 "configure"
 #include "confdefs.h"
 #ifdef _AIX
   yes
@@ -845,6 +955,7 @@ rm -f conftest*
 
 
 echo $ac_n "checking for POSIXized ISC""... $ac_c" 1>&6
+echo "configure:959: checking for POSIXized ISC" >&5
 if test -d /etc/conf/kconfig.d &&
   grep _POSIX_VERSION /usr/include/sys/unistd.h >/dev/null 2>&1
 then
@@ -864,23 +975,27 @@ else
   ISC=
 fi
 
-ac_safe=`echo "minix/config.h" | tr './\055' '___'`
+ac_safe=`echo "minix/config.h" | sed 'y%./+-%__p_%'`
 echo $ac_n "checking for minix/config.h""... $ac_c" 1>&6
+echo "configure:981: checking for minix/config.h" >&5
 if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 874 "configure"
+#line 986 "configure"
 #include "confdefs.h"
 #include <minix/config.h>
 EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:991: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
   eval "ac_cv_header_$ac_safe=yes"
 else
   echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   eval "ac_cv_header_$ac_safe=no"
 fi
@@ -910,104 +1025,29 @@ EOF
 fi
 
 
-# If we cannot run a trivial program, we must be cross compiling.
-echo $ac_n "checking whether cross-compiling""... $ac_c" 1>&6
-if eval "test \"`echo '$''{'ac_cv_c_cross'+set}'`\" = set"; then
-  echo $ac_n "(cached) $ac_c" 1>&6
-else
-  if test "$cross_compiling" = yes; then
-  ac_cv_c_cross=yes
-else
-cat > conftest.$ac_ext <<EOF
-#line 923 "configure"
-#include "confdefs.h"
-main(){return(0);}
-EOF
-eval $ac_link
-if test -s conftest && (./conftest; exit) 2>/dev/null; then
-  ac_cv_c_cross=no
-else
-  ac_cv_c_cross=yes
-fi
-fi
-rm -fr conftest*
-fi
-
-echo "$ac_t""$ac_cv_c_cross" 1>&6
-cross_compiling=$ac_cv_c_cross
-
-echo $ac_n "checking whether the compiler ($CC $CFLAGS $LDFLAGS) actually works""... $ac_c" 1>&6
-
-  ac_ext=c
-# CFLAGS is not in ac_cpp because -g, -O, etc. are not valid cpp options.
-ac_cpp='echo $CPP $CPPFLAGS 1>&5;
-$CPP $CPPFLAGS'
-ac_compile='echo ${CC-cc} -c $CFLAGS $CPPFLAGS conftest.$ac_ext 1>&5;
-${CC-cc} -c $CFLAGS $CPPFLAGS conftest.$ac_ext 1>&5 2>&5'
-ac_link='echo ${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS 1>&5;
-${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS 1>&5 2>&5'
-
-  if test "$cross_compiling" = yes; then
-               cat > conftest.$ac_ext <<EOF
-#line 953 "configure"
-#include "confdefs.h"
-
-int main() { return 0; }
-int t() {
-
-; return 0; }
-EOF
-if eval $ac_link; then
-  rm -rf conftest*
-  am_cv_prog_cc_works=yes
-else
-  rm -rf conftest*
-  am_cv_prog_cc_works=no
-fi
-rm -f conftest*
-
-else
-cat > conftest.$ac_ext <<EOF
-#line 972 "configure"
-#include "confdefs.h"
-main() { exit(0); }
-EOF
-eval $ac_link
-if test -s conftest && (./conftest; exit) 2>/dev/null; then
-  am_cv_prog_cc_works=yes
-else
-  am_cv_prog_cc_works=no
-fi
-fi
-rm -fr conftest*
-
-case "$am_cv_prog_cc_works" in
-  *no) { echo "configure: error: Installation or configuration problem: C compiler cannot cr
-eate executables." 1>&2; exit 1; } ;;
-  *yes) ;;
-esac
-echo "$ac_t""yes" 1>&6
-
-
 echo $ac_n "checking for ANSI C header files""... $ac_c" 1>&6
+echo "configure:1030: checking for ANSI C header files" >&5
 if eval "test \"`echo '$''{'ac_cv_header_stdc'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 998 "configure"
+#line 1035 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 #include <stdarg.h>
 #include <string.h>
 #include <float.h>
 EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1043: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
   ac_cv_header_stdc=yes
 else
   echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   ac_cv_header_stdc=no
 fi
@@ -1016,7 +1056,7 @@ rm -f conftest*
 if test $ac_cv_header_stdc = yes; then
   # SunOS 4.x string.h does not declare mem*, contrary to ANSI.
 cat > conftest.$ac_ext <<EOF
-#line 1020 "configure"
+#line 1060 "configure"
 #include "confdefs.h"
 #include <string.h>
 EOF
@@ -1034,7 +1074,7 @@ fi
 if test $ac_cv_header_stdc = yes; then
   # ISC 2.0.2 stdlib.h does not declare free, contrary to ANSI.
 cat > conftest.$ac_ext <<EOF
-#line 1038 "configure"
+#line 1078 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 EOF
@@ -1054,8 +1094,8 @@ if test $ac_cv_header_stdc = yes; then
 if test "$cross_compiling" = yes; then
   :
 else
-cat > conftest.$ac_ext <<EOF
-#line 1059 "configure"
+  cat > conftest.$ac_ext <<EOF
+#line 1099 "configure"
 #include "confdefs.h"
 #include <ctype.h>
 #define ISLOWER(c) ('a' <= (c) && (c) <= 'z')
@@ -1066,15 +1106,19 @@ if (XOR (islower (i), ISLOWER (i)) || toupper (i) != TOUPPER (i)) exit(2);
 exit (0); }
 
 EOF
-eval $ac_link
-if test -s conftest && (./conftest; exit) 2>/dev/null; then
+if { (eval echo configure:1110: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest && (./conftest; exit) 2>/dev/null
+then
   :
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -fr conftest*
   ac_cv_header_stdc=no
 fi
-fi
 rm -fr conftest*
 fi
+
+fi
 fi
 
 echo "$ac_t""$ac_cv_header_stdc" 1>&6
@@ -1086,11 +1130,12 @@ EOF
 fi
 
 echo $ac_n "checking for sys/wait.h that is POSIX.1 compatible""... $ac_c" 1>&6
+echo "configure:1134: checking for sys/wait.h that is POSIX.1 compatible" >&5
 if eval "test \"`echo '$''{'ac_cv_header_sys_wait_h'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1094 "configure"
+#line 1139 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 #include <sys/wait.h>
@@ -1100,22 +1145,22 @@ else
 #ifndef WIFEXITED
 #define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
 #endif
-int main() { return 0; }
-int t() {
+int main() {
 int s;
 wait (&s);
 s = WIFEXITED (s) ? WEXITSTATUS (s) : 1;
 ; return 0; }
 EOF
-if eval $ac_compile; then
+if { (eval echo configure:1155: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_header_sys_wait_h=yes
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   ac_cv_header_sys_wait_h=no
 fi
 rm -f conftest*
-
 fi
 
 echo "$ac_t""$ac_cv_header_sys_wait_h" 1>&6
@@ -1128,23 +1173,27 @@ fi
 
 for ac_hdr in limits.h locale.h stdarg.h unistd.h signum.h sys/param.h string.h
 do
-ac_safe=`echo "$ac_hdr" | tr './\055' '___'`
+ac_safe=`echo "$ac_hdr" | sed 'y%./+-%__p_%'`
 echo $ac_n "checking for $ac_hdr""... $ac_c" 1>&6
+echo "configure:1179: checking for $ac_hdr" >&5
 if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1138 "configure"
+#line 1184 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1189: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
   eval "ac_cv_header_$ac_safe=yes"
 else
   echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   eval "ac_cv_header_$ac_safe=no"
 fi
@@ -1152,7 +1201,7 @@ rm -f conftest*
 fi
 if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
   echo "$ac_t""yes" 1>&6
-    ac_tr_hdr=HAVE_`echo $ac_hdr | tr 'abcdefghijklmnopqrstuvwxyz./\055' 'ABCDEFGHIJKLMNOPQRSTUVWXYZ___'`
+    ac_tr_hdr=HAVE_`echo $ac_hdr | sed 'y%abcdefghijklmnopqrstuvwxyz./-%ABCDEFGHIJKLMNOPQRSTUVWXYZ___%'`
   cat >> confdefs.h <<EOF
 #define $ac_tr_hdr 1
 EOF
@@ -1166,23 +1215,27 @@ if test "$ac_cv_header_string_h" = yes
 then
 	for ac_hdr in memory.h
 do
-ac_safe=`echo "$ac_hdr" | tr './\055' '___'`
+ac_safe=`echo "$ac_hdr" | sed 'y%./+-%__p_%'`
 echo $ac_n "checking for $ac_hdr""... $ac_c" 1>&6
+echo "configure:1221: checking for $ac_hdr" >&5
 if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1176 "configure"
+#line 1226 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1231: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
   eval "ac_cv_header_$ac_safe=yes"
 else
   echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   eval "ac_cv_header_$ac_safe=no"
 fi
@@ -1190,7 +1243,7 @@ rm -f conftest*
 fi
 if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
   echo "$ac_t""yes" 1>&6
-    ac_tr_hdr=HAVE_`echo $ac_hdr | tr 'abcdefghijklmnopqrstuvwxyz./\055' 'ABCDEFGHIJKLMNOPQRSTUVWXYZ___'`
+    ac_tr_hdr=HAVE_`echo $ac_hdr | sed 'y%abcdefghijklmnopqrstuvwxyz./-%ABCDEFGHIJKLMNOPQRSTUVWXYZ___%'`
   cat >> confdefs.h <<EOF
 #define $ac_tr_hdr 1
 EOF
@@ -1203,23 +1256,27 @@ done
 else
 	for ac_hdr in strings.h
 do
-ac_safe=`echo "$ac_hdr" | tr './\055' '___'`
+ac_safe=`echo "$ac_hdr" | sed 'y%./+-%__p_%'`
 echo $ac_n "checking for $ac_hdr""... $ac_c" 1>&6
+echo "configure:1262: checking for $ac_hdr" >&5
 if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1213 "configure"
+#line 1267 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
-eval "$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1272: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
   eval "ac_cv_header_$ac_safe=yes"
 else
   echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   eval "ac_cv_header_$ac_safe=no"
 fi
@@ -1227,7 +1284,7 @@ rm -f conftest*
 fi
 if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
   echo "$ac_t""yes" 1>&6
-    ac_tr_hdr=HAVE_`echo $ac_hdr | tr 'abcdefghijklmnopqrstuvwxyz./\055' 'ABCDEFGHIJKLMNOPQRSTUVWXYZ___'`
+    ac_tr_hdr=HAVE_`echo $ac_hdr | sed 'y%abcdefghijklmnopqrstuvwxyz./-%ABCDEFGHIJKLMNOPQRSTUVWXYZ___%'`
   cat >> confdefs.h <<EOF
 #define $ac_tr_hdr 1
 EOF
@@ -1240,19 +1297,21 @@ done
 fi
 
 echo $ac_n "checking for pid_t""... $ac_c" 1>&6
+echo "configure:1301: checking for pid_t" >&5
 if eval "test \"`echo '$''{'ac_cv_type_pid_t'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1248 "configure"
+#line 1306 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 #if STDC_HEADERS
 #include <stdlib.h>
+#include <stddef.h>
 #endif
 EOF
 if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  egrep "pid_t" >/dev/null 2>&1; then
+  egrep "pid_t[^a-zA-Z_0-9]" >/dev/null 2>&1; then
   rm -rf conftest*
   ac_cv_type_pid_t=yes
 else
@@ -1271,11 +1330,12 @@ EOF
 fi
 
 echo $ac_n "checking return type of signal handlers""... $ac_c" 1>&6
+echo "configure:1334: checking return type of signal handlers" >&5
 if eval "test \"`echo '$''{'ac_cv_type_signal'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1279 "configure"
+#line 1339 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 #include <signal.h>
@@ -1288,20 +1348,20 @@ extern "C" void (*signal (int, void (*)(int)))(int);
 void (*signal ()) ();
 #endif
 
-int main() { return 0; }
-int t() {
+int main() {
 int i;
 ; return 0; }
 EOF
-if eval $ac_compile; then
+if { (eval echo configure:1356: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_type_signal=void
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   ac_cv_type_signal=int
 fi
 rm -f conftest*
-
 fi
 
 echo "$ac_t""$ac_cv_type_signal" 1>&6
@@ -1311,19 +1371,21 @@ EOF
 
 
 echo $ac_n "checking for size_t""... $ac_c" 1>&6
+echo "configure:1375: checking for size_t" >&5
 if eval "test \"`echo '$''{'ac_cv_type_size_t'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1319 "configure"
+#line 1380 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 #if STDC_HEADERS
 #include <stdlib.h>
+#include <stddef.h>
 #endif
 EOF
 if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  egrep "size_t" >/dev/null 2>&1; then
+  egrep "size_t[^a-zA-Z_0-9]" >/dev/null 2>&1; then
   rm -rf conftest*
   ac_cv_type_size_t=yes
 else
@@ -1342,11 +1404,12 @@ EOF
 fi
 
 echo $ac_n "checking for uid_t in sys/types.h""... $ac_c" 1>&6
+echo "configure:1408: checking for uid_t in sys/types.h" >&5
 if eval "test \"`echo '$''{'ac_cv_type_uid_t'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1350 "configure"
+#line 1413 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 EOF
@@ -1375,14 +1438,15 @@ EOF
 fi
 
 echo $ac_n "checking type of array argument to getgroups""... $ac_c" 1>&6
+echo "configure:1442: checking type of array argument to getgroups" >&5
 if eval "test \"`echo '$''{'ac_cv_type_getgroups'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   if test "$cross_compiling" = yes; then
   ac_cv_type_getgroups=cross
 else
-cat > conftest.$ac_ext <<EOF
-#line 1386 "configure"
+  cat > conftest.$ac_ext <<EOF
+#line 1450 "configure"
 #include "confdefs.h"
 
 /* Thanks to Mike Rendell for this test.  */
@@ -1407,17 +1471,21 @@ main()
 }
 
 EOF
-eval $ac_link
-if test -s conftest && (./conftest; exit) 2>/dev/null; then
+if { (eval echo configure:1475: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest && (./conftest; exit) 2>/dev/null
+then
     ac_cv_type_getgroups=gid_t
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -fr conftest*
   ac_cv_type_getgroups=int
 fi
-fi
 rm -fr conftest*
+fi
+
 if test $ac_cv_type_getgroups = cross; then
         cat > conftest.$ac_ext <<EOF
-#line 1421 "configure"
+#line 1489 "configure"
 #include "confdefs.h"
 #include <unistd.h>
 EOF
@@ -1441,7 +1509,7 @@ EOF
 
 
 cat > conftest.$ac_ext <<EOF
-#line 1445 "configure"
+#line 1513 "configure"
 #include "confdefs.h"
 #include <stdio.h>
 EOF
@@ -1468,27 +1536,28 @@ then
 	# The Ultrix 4.2 mips builtin alloca declared by alloca.h only works
 # for constant arguments.  Useless!
 echo $ac_n "checking for working alloca.h""... $ac_c" 1>&6
+echo "configure:1540: checking for working alloca.h" >&5
 if eval "test \"`echo '$''{'ac_cv_header_alloca_h'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1476 "configure"
+#line 1545 "configure"
 #include "confdefs.h"
 #include <alloca.h>
-int main() { return 0; }
-int t() {
+int main() {
 char *p = alloca(2 * sizeof(int));
 ; return 0; }
 EOF
-if eval $ac_link; then
+if { (eval echo configure:1552: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
   rm -rf conftest*
   ac_cv_header_alloca_h=yes
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   ac_cv_header_alloca_h=no
 fi
 rm -f conftest*
-
 fi
 
 echo "$ac_t""$ac_cv_header_alloca_h" 1>&6
@@ -1500,11 +1569,12 @@ EOF
 fi
 
 echo $ac_n "checking for alloca""... $ac_c" 1>&6
-if eval "test \"`echo '$''{'ac_cv_func_alloca'+set}'`\" = set"; then
+echo "configure:1573: checking for alloca" >&5
+if eval "test \"`echo '$''{'ac_cv_func_alloca_works'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1508 "configure"
+#line 1578 "configure"
 #include "confdefs.h"
 
 #ifdef __GNUC__
@@ -1523,31 +1593,31 @@ char *alloca ();
 # endif
 #endif
 
-int main() { return 0; }
-int t() {
+int main() {
 char *p = (char *) alloca(1);
 ; return 0; }
 EOF
-if eval $ac_link; then
+if { (eval echo configure:1601: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
   rm -rf conftest*
-  ac_cv_func_alloca=yes
+  ac_cv_func_alloca_works=yes
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
-  ac_cv_func_alloca=no
+  ac_cv_func_alloca_works=no
 fi
 rm -f conftest*
-
 fi
 
-echo "$ac_t""$ac_cv_func_alloca" 1>&6
-if test $ac_cv_func_alloca = yes; then
+echo "$ac_t""$ac_cv_func_alloca_works" 1>&6
+if test $ac_cv_func_alloca_works = yes; then
   cat >> confdefs.h <<\EOF
 #define HAVE_ALLOCA 1
 EOF
 
 fi
 
-if test $ac_cv_func_alloca = no; then
+if test $ac_cv_func_alloca_works = no; then
   # The SVR3 libPW and SVR4 libucb both contain incompatible functions
   # that cause trouble.  Some versions do not even contain alloca or
   # contain a buggy version.  If you still want to use their alloca,
@@ -1559,11 +1629,12 @@ EOF
 
 
 echo $ac_n "checking whether alloca needs Cray hooks""... $ac_c" 1>&6
+echo "configure:1633: checking whether alloca needs Cray hooks" >&5
 if eval "test \"`echo '$''{'ac_cv_os_cray'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1567 "configure"
+#line 1638 "configure"
 #include "confdefs.h"
 #if defined(CRAY) && ! defined(CRAY2)
 webecray
@@ -1588,20 +1659,22 @@ echo "$ac_t""$ac_cv_os_cray" 1>&6
 if test $ac_cv_os_cray = yes; then
 for ac_func in _getb67 GETB67 getb67; do
   echo $ac_n "checking for $ac_func""... $ac_c" 1>&6
+echo "configure:1663: checking for $ac_func" >&5
 if eval "test \"`echo '$''{'ac_cv_func_$ac_func'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1596 "configure"
+#line 1668 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char $ac_func(); below.  */
 #include <assert.h>
 /* Override any gcc2 internal prototype to avoid an error.  */
+/* We use char because int might match the return type of a gcc2
+    builtin and then its argument prototype would still apply.  */
 char $ac_func();
 
-int main() { return 0; }
-int t() {
+int main() {
 
 /* The GNU C library defines this for functions which it implements
     to always fail with ENOSYS.  Some functions are actually named
@@ -1614,16 +1687,18 @@ $ac_func();
 
 ; return 0; }
 EOF
-if eval $ac_link; then
+if { (eval echo configure:1691: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
   rm -rf conftest*
   eval "ac_cv_func_$ac_func=yes"
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   eval "ac_cv_func_$ac_func=no"
 fi
 rm -f conftest*
-
 fi
+
 if eval "test \"`echo '$ac_cv_func_'$ac_func`\" = yes"; then
   echo "$ac_t""yes" 1>&6
   cat >> confdefs.h <<EOF
@@ -1639,14 +1714,15 @@ done
 fi
 
 echo $ac_n "checking stack direction for C alloca""... $ac_c" 1>&6
+echo "configure:1718: checking stack direction for C alloca" >&5
 if eval "test \"`echo '$''{'ac_cv_c_stack_direction'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   if test "$cross_compiling" = yes; then
   ac_cv_c_stack_direction=0
 else
-cat > conftest.$ac_ext <<EOF
-#line 1650 "configure"
+  cat > conftest.$ac_ext <<EOF
+#line 1726 "configure"
 #include "confdefs.h"
 find_stack_direction ()
 {
@@ -1665,16 +1741,20 @@ main ()
   exit (find_stack_direction() < 0);
 }
 EOF
-eval $ac_link
-if test -s conftest && (./conftest; exit) 2>/dev/null; then
+if { (eval echo configure:1745: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest && (./conftest; exit) 2>/dev/null
+then
   ac_cv_c_stack_direction=1
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -fr conftest*
   ac_cv_c_stack_direction=-1
 fi
-fi
 rm -fr conftest*
 fi
 
+fi
+
 echo "$ac_t""$ac_cv_c_stack_direction" 1>&6
 cat >> confdefs.h <<EOF
 #define STACK_DIRECTION $ac_cv_c_stack_direction
@@ -1688,20 +1768,22 @@ cat >> confdefs.h <<\EOF
 EOF
 
 echo $ac_n "checking for vprintf""... $ac_c" 1>&6
+echo "configure:1772: checking for vprintf" >&5
 if eval "test \"`echo '$''{'ac_cv_func_vprintf'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1696 "configure"
+#line 1777 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char vprintf(); below.  */
 #include <assert.h>
 /* Override any gcc2 internal prototype to avoid an error.  */
+/* We use char because int might match the return type of a gcc2
+    builtin and then its argument prototype would still apply.  */
 char vprintf();
 
-int main() { return 0; }
-int t() {
+int main() {
 
 /* The GNU C library defines this for functions which it implements
     to always fail with ENOSYS.  Some functions are actually named
@@ -1714,16 +1796,18 @@ vprintf();
 
 ; return 0; }
 EOF
-if eval $ac_link; then
+if { (eval echo configure:1800: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
   rm -rf conftest*
   eval "ac_cv_func_vprintf=yes"
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   eval "ac_cv_func_vprintf=no"
 fi
 rm -f conftest*
-
 fi
+
 if eval "test \"`echo '$ac_cv_func_'vprintf`\" = yes"; then
   echo "$ac_t""yes" 1>&6
   cat >> confdefs.h <<\EOF
@@ -1736,20 +1820,22 @@ fi
 
 if test "$ac_cv_func_vprintf" != yes; then
 echo $ac_n "checking for _doprnt""... $ac_c" 1>&6
+echo "configure:1824: checking for _doprnt" >&5
 if eval "test \"`echo '$''{'ac_cv_func__doprnt'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1744 "configure"
+#line 1829 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char _doprnt(); below.  */
 #include <assert.h>
 /* Override any gcc2 internal prototype to avoid an error.  */
+/* We use char because int might match the return type of a gcc2
+    builtin and then its argument prototype would still apply.  */
 char _doprnt();
 
-int main() { return 0; }
-int t() {
+int main() {
 
 /* The GNU C library defines this for functions which it implements
     to always fail with ENOSYS.  Some functions are actually named
@@ -1762,16 +1848,18 @@ _doprnt();
 
 ; return 0; }
 EOF
-if eval $ac_link; then
+if { (eval echo configure:1852: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
   rm -rf conftest*
   eval "ac_cv_func__doprnt=yes"
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   eval "ac_cv_func__doprnt=no"
 fi
 rm -f conftest*
-
 fi
+
 if eval "test \"`echo '$ac_cv_func_'_doprnt`\" = yes"; then
   echo "$ac_t""yes" 1>&6
   cat >> confdefs.h <<\EOF
@@ -1785,26 +1873,32 @@ fi
 fi
 
 
-echo $ac_n "checking for -lm""... $ac_c" 1>&6
-ac_lib_var=`echo m | tr '.-/+' '___p'`
+echo $ac_n "checking for fmod in -lm""... $ac_c" 1>&6
+echo "configure:1878: checking for fmod in -lm" >&5
+ac_lib_var=`echo m'_'fmod | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_lib_$ac_lib_var'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   ac_save_LIBS="$LIBS"
 LIBS="-lm  $LIBS"
 cat > conftest.$ac_ext <<EOF
-#line 1797 "configure"
+#line 1886 "configure"
 #include "confdefs.h"
+/* Override any gcc2 internal prototype to avoid an error.  */
+/* We use char because int might match the return type of a gcc2
+    builtin and then its argument prototype would still apply.  */
+char fmod();
 
-int main() { return 0; }
-int t() {
+int main() {
 fmod()
 ; return 0; }
 EOF
-if eval $ac_link; then
+if { (eval echo configure:1897: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
   rm -rf conftest*
   eval "ac_cv_lib_$ac_lib_var=yes"
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   eval "ac_cv_lib_$ac_lib_var=no"
 fi
@@ -1814,7 +1908,8 @@ LIBS="$ac_save_LIBS"
 fi
 if eval "test \"`echo '$ac_cv_lib_'$ac_lib_var`\" = yes"; then
   echo "$ac_t""yes" 1>&6
-    ac_tr_lib=HAVE_LIB`echo m | tr 'abcdefghijklmnopqrstuvwxyz' 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'`
+    ac_tr_lib=HAVE_LIB`echo m | sed -e 's/[^a-zA-Z0-9_]/_/g' \
+    -e 'y/abcdefghijklmnopqrstuvwxyz/ABCDEFGHIJKLMNOPQRSTUVWXYZ/'`
   cat >> confdefs.h <<EOF
 #define $ac_tr_lib 1
 EOF
@@ -1829,20 +1924,22 @@ for ac_func in madvise memset memcpy memcmp fmod setlocale strchr strerror \
 		strftime strncasecmp strtod system tzset
 do
 echo $ac_n "checking for $ac_func""... $ac_c" 1>&6
+echo "configure:1928: checking for $ac_func" >&5
 if eval "test \"`echo '$''{'ac_cv_func_$ac_func'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1837 "configure"
+#line 1933 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char $ac_func(); below.  */
 #include <assert.h>
 /* Override any gcc2 internal prototype to avoid an error.  */
+/* We use char because int might match the return type of a gcc2
+    builtin and then its argument prototype would still apply.  */
 char $ac_func();
 
-int main() { return 0; }
-int t() {
+int main() {
 
 /* The GNU C library defines this for functions which it implements
     to always fail with ENOSYS.  Some functions are actually named
@@ -1855,16 +1952,18 @@ $ac_func();
 
 ; return 0; }
 EOF
-if eval $ac_link; then
+if { (eval echo configure:1956: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
   rm -rf conftest*
   eval "ac_cv_func_$ac_func=yes"
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   eval "ac_cv_func_$ac_func=no"
 fi
 rm -f conftest*
-
 fi
+
 if eval "test \"`echo '$ac_cv_func_'$ac_func`\" = yes"; then
   echo "$ac_t""yes" 1>&6
     ac_tr_func=HAVE_`echo $ac_func | tr 'abcdefghijklmnopqrstuvwxyz' 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'`
@@ -1878,23 +1977,65 @@ fi
 done
 
 
-for ac_func in valloc getpagesize
+for ac_hdr in unistd.h
+do
+ac_safe=`echo "$ac_hdr" | sed 'y%./+-%__p_%'`
+echo $ac_n "checking for $ac_hdr""... $ac_c" 1>&6
+echo "configure:1985: checking for $ac_hdr" >&5
+if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
+  echo $ac_n "(cached) $ac_c" 1>&6
+else
+  cat > conftest.$ac_ext <<EOF
+#line 1990 "configure"
+#include "confdefs.h"
+#include <$ac_hdr>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1995: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  eval "ac_cv_header_$ac_safe=yes"
+else
+  echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -rf conftest*
+  eval "ac_cv_header_$ac_safe=no"
+fi
+rm -f conftest*
+fi
+if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
+  echo "$ac_t""yes" 1>&6
+    ac_tr_hdr=HAVE_`echo $ac_hdr | sed 'y%abcdefghijklmnopqrstuvwxyz./-%ABCDEFGHIJKLMNOPQRSTUVWXYZ___%'`
+  cat >> confdefs.h <<EOF
+#define $ac_tr_hdr 1
+EOF
+ 
+else
+  echo "$ac_t""no" 1>&6
+fi
+done
+
+for ac_func in getpagesize
 do
 echo $ac_n "checking for $ac_func""... $ac_c" 1>&6
+echo "configure:2024: checking for $ac_func" >&5
 if eval "test \"`echo '$''{'ac_cv_func_$ac_func'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1889 "configure"
+#line 2029 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char $ac_func(); below.  */
 #include <assert.h>
 /* Override any gcc2 internal prototype to avoid an error.  */
+/* We use char because int might match the return type of a gcc2
+    builtin and then its argument prototype would still apply.  */
 char $ac_func();
 
-int main() { return 0; }
-int t() {
+int main() {
 
 /* The GNU C library defines this for functions which it implements
     to always fail with ENOSYS.  Some functions are actually named
@@ -1907,16 +2048,18 @@ $ac_func();
 
 ; return 0; }
 EOF
-if eval $ac_link; then
+if { (eval echo configure:2052: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
   rm -rf conftest*
   eval "ac_cv_func_$ac_func=yes"
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   eval "ac_cv_func_$ac_func=no"
 fi
 rm -f conftest*
-
 fi
+
 if eval "test \"`echo '$ac_cv_func_'$ac_func`\" = yes"; then
   echo "$ac_t""yes" 1>&6
     ac_tr_func=HAVE_`echo $ac_func | tr 'abcdefghijklmnopqrstuvwxyz' 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'`
@@ -1930,94 +2073,170 @@ fi
 done
 
 echo $ac_n "checking for working mmap""... $ac_c" 1>&6
-if eval "test \"`echo '$''{'ac_cv_func_mmap'+set}'`\" = set"; then
+echo "configure:2077: checking for working mmap" >&5
+if eval "test \"`echo '$''{'ac_cv_func_mmap_fixed_mapped'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   if test "$cross_compiling" = yes; then
-  ac_cv_func_mmap=no
+  ac_cv_func_mmap_fixed_mapped=no
 else
-cat > conftest.$ac_ext <<EOF
-#line 1941 "configure"
+  cat > conftest.$ac_ext <<EOF
+#line 2085 "configure"
 #include "confdefs.h"
 
-/* Thanks to Mike Haertel and Jim Avera for this test. */
+/* Thanks to Mike Haertel and Jim Avera for this test.
+   Here is a matrix of mmap possibilities:
+	mmap private not fixed
+	mmap private fixed at somewhere currently unmapped
+	mmap private fixed at somewhere already mapped
+	mmap shared not fixed
+	mmap shared fixed at somewhere currently unmapped
+	mmap shared fixed at somewhere already mapped
+   For private mappings, we should verify that changes cannot be read()
+   back from the file, nor mmap's back from the file at a different
+   address.  (There have been systems where private was not correctly
+   implemented like the infamous i386 svr4.0, and systems where the
+   VM page cache was not coherent with the filesystem buffer cache
+   like early versions of FreeBSD and possibly contemporary NetBSD.)
+   For shared mappings, we should conversely verify that changes get
+   propogated back to all the places they're supposed to be.
+
+   Grep wants private fixed already mapped.
+   The main things grep needs to know about mmap are:
+   * does it exist and is it safe to write into the mmap'd area
+   * how to use it (BSD variants)  */
 #include <sys/types.h>
 #include <fcntl.h>
 #include <sys/mman.h>
 
+/* This mess was copied from the GNU getpagesize.h.  */
 #ifndef HAVE_GETPAGESIZE
-# include <sys/param.h>
-# ifdef EXEC_PAGESIZE
-#  define getpagesize() EXEC_PAGESIZE
-# else
-#  ifdef NBPG
-#   define getpagesize() NBPG * CLSIZE
-#   ifndef CLSIZE
-#    define CLSIZE 1
-#   endif
-#  else
-#   ifdef NBPC
-#    define getpagesize() NBPC
-#   else
-#    define getpagesize() PAGESIZE /* SVR4 */
-#   endif
-#  endif
+# ifdef HAVE_UNISTD_H
+#  include <unistd.h>
 # endif
-#endif
 
-#ifndef HAVE_VALLOC
-# define valloc malloc
-#endif
+/* Assume that all systems that can run configure have sys/param.h.  */
+# ifndef HAVE_SYS_PARAM_H
+#  define HAVE_SYS_PARAM_H 1
+# endif
+
+# ifdef _SC_PAGESIZE
+#  define getpagesize() sysconf(_SC_PAGESIZE)
+# else /* no _SC_PAGESIZE */
+#  ifdef HAVE_SYS_PARAM_H
+#   include <sys/param.h>
+#   ifdef EXEC_PAGESIZE
+#    define getpagesize() EXEC_PAGESIZE
+#   else /* no EXEC_PAGESIZE */
+#    ifdef NBPG
+#     define getpagesize() NBPG * CLSIZE
+#     ifndef CLSIZE
+#      define CLSIZE 1
+#     endif /* no CLSIZE */
+#    else /* no NBPG */
+#     ifdef NBPC
+#      define getpagesize() NBPC
+#     else /* no NBPC */
+#      ifdef PAGESIZE
+#       define getpagesize() PAGESIZE
+#      endif /* PAGESIZE */
+#     endif /* no NBPC */
+#    endif /* no NBPG */
+#   endif /* no EXEC_PAGESIZE */
+#  else /* no HAVE_SYS_PARAM_H */
+#   define getpagesize() 8192	/* punt totally */
+#  endif /* no HAVE_SYS_PARAM_H */
+# endif /* no _SC_PAGESIZE */
+
+#endif /* no HAVE_GETPAGESIZE */
 
 #ifdef __cplusplus
-extern "C" { void *valloc(unsigned), *malloc(unsigned); }
+extern "C" { void *malloc(unsigned); }
 #else
-char *valloc(), *malloc();
+char *malloc();
 #endif
 
 int
 main()
 {
-  char *buf1, *buf2, *buf3;
-  int i = getpagesize(), j;
-  int i2 = i * 2;
-  int fd;
-
-  buf1 = (char *)valloc(i2);
-  buf2 = (char *)valloc(i);
-  buf3 = (char *)malloc(i2);
-  for (j = 0; j < i2; ++j)
-    *(buf1 + j) = rand();
-  fd = open("conftestmmap", O_CREAT | O_RDWR, 0666);
-  write(fd, buf1, i2);
-  mmap(buf2, i, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE, fd, 0);
-  for (j = 0; j < i; ++j)
-    if (*(buf1 + j) != *(buf2 + j))
-      exit(1);
-  lseek(fd, (long)i, 0);
-  read(fd, buf2, i); /* read into mapped memory -- file should not change */
-  /* (it does in i386 SVR4.0 - Jim Avera, jima@netcom.com) */
-  lseek(fd, (long)0, 0);
-  read(fd, buf3, i2);
-  for (j = 0; j < i2; ++j)
-    if (*(buf1 + j) != *(buf3 + j))
-      exit(1);
-  exit(0);
+	char *data, *data2, *data3;
+	int i, pagesize;
+	int fd;
+
+	pagesize = getpagesize();
+
+	/*
+	 * First, make a file with some known garbage in it.
+	 */
+	data = malloc(pagesize);
+	if (!data)
+		exit(1);
+	for (i = 0; i < pagesize; ++i)
+		*(data + i) = rand();
+	umask(0);
+	fd = creat("conftestmmap", 0600);
+	if (fd < 0)
+		exit(1);
+	if (write(fd, data, pagesize) != pagesize)
+		exit(1);
+	close(fd);
+
+	/*
+	 * Next, try to mmap the file at a fixed address which
+	 * already has something else allocated at it.  If we can,
+	 * also make sure that we see the same garbage.
+	 */
+	fd = open("conftestmmap", O_RDWR);
+	if (fd < 0)
+		exit(1);
+	data2 = malloc(2 * pagesize);
+	if (!data2)
+		exit(1);
+	data2 += (pagesize - ((int) data2 & (pagesize - 1))) & (pagesize - 1);
+	if (data2 != mmap(data2, pagesize, PROT_READ | PROT_WRITE,
+	    MAP_PRIVATE | MAP_FIXED, fd, 0L))
+		exit(1);
+	for (i = 0; i < pagesize; ++i)
+		if (*(data + i) != *(data2 + i))
+			exit(1);
+
+	/*
+	 * Finally, make sure that changes to the mapped area
+	 * do not percolate back to the file as seen by read().
+	 * (This is a bug on some variants of i386 svr4.0.)
+	 */
+	for (i = 0; i < pagesize; ++i)
+		*(data2 + i) = *(data2 + i) + 1;
+	data3 = malloc(pagesize);
+	if (!data3)
+		exit(1);
+	if (read(fd, data3, pagesize) != pagesize)
+		exit(1);
+	for (i = 0; i < pagesize; ++i)
+		if (*(data + i) != *(data3 + i))
+			exit(1);
+	close(fd);
+	unlink("conftestmmap");
+	exit(0);
 }
 
 EOF
-eval $ac_link
-if test -s conftest && (./conftest; exit) 2>/dev/null; then
-  ac_cv_func_mmap=yes
+if { (eval echo configure:2225: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest && (./conftest; exit) 2>/dev/null
+then
+  ac_cv_func_mmap_fixed_mapped=yes
 else
-  ac_cv_func_mmap=no
-fi
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -fr conftest*
+  ac_cv_func_mmap_fixed_mapped=no
 fi
 rm -fr conftest*
 fi
 
-echo "$ac_t""$ac_cv_func_mmap" 1>&6
-if test $ac_cv_func_mmap = yes; then
+fi
+
+echo "$ac_t""$ac_cv_func_mmap_fixed_mapped" 1>&6
+if test $ac_cv_func_mmap_fixed_mapped = yes; then
   cat >> confdefs.h <<\EOF
 #define HAVE_MMAP 1
 EOF
@@ -2026,14 +2245,15 @@ fi
 
 
 echo $ac_n "checking whether getpgrp takes no argument""... $ac_c" 1>&6
+echo "configure:2249: checking whether getpgrp takes no argument" >&5
 if eval "test \"`echo '$''{'ac_cv_func_getpgrp_void'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   if test "$cross_compiling" = yes; then
   { echo "configure: error: cannot check getpgrp if cross compiling" 1>&2; exit 1; }
 else
-cat > conftest.$ac_ext <<EOF
-#line 2037 "configure"
+  cat > conftest.$ac_ext <<EOF
+#line 2257 "configure"
 #include "confdefs.h"
 
 /*
@@ -2088,14 +2308,18 @@ main()
 }
 
 EOF
-eval $ac_link
-if test -s conftest && (./conftest; exit) 2>/dev/null; then
+if { (eval echo configure:2312: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest && (./conftest; exit) 2>/dev/null
+then
   ac_cv_func_getpgrp_void=yes
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -fr conftest*
   ac_cv_func_getpgrp_void=no
 fi
-fi
 rm -fr conftest*
+fi
+
 
 fi
 
@@ -2109,28 +2333,29 @@ fi
 
 
 echo $ac_n "checking for st_blksize in struct stat""... $ac_c" 1>&6
+echo "configure:2337: checking for st_blksize in struct stat" >&5
 if eval "test \"`echo '$''{'ac_cv_struct_st_blksize'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2117 "configure"
+#line 2342 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 #include <sys/stat.h>
-int main() { return 0; }
-int t() {
+int main() {
 struct stat s; s.st_blksize;
 ; return 0; }
 EOF
-if eval $ac_compile; then
+if { (eval echo configure:2350: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_struct_st_blksize=yes
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   ac_cv_struct_st_blksize=no
 fi
 rm -f conftest*
-
 fi
 
 echo "$ac_t""$ac_cv_struct_st_blksize" 1>&6
@@ -2142,29 +2367,30 @@ EOF
 fi
 
 echo $ac_n "checking whether time.h and sys/time.h may both be included""... $ac_c" 1>&6
+echo "configure:2371: checking whether time.h and sys/time.h may both be included" >&5
 if eval "test \"`echo '$''{'ac_cv_header_time'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2150 "configure"
+#line 2376 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 #include <sys/time.h>
 #include <time.h>
-int main() { return 0; }
-int t() {
+int main() {
 struct tm *tp;
 ; return 0; }
 EOF
-if eval $ac_compile; then
+if { (eval echo configure:2385: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_header_time=yes
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   ac_cv_header_time=no
 fi
 rm -f conftest*
-
 fi
 
 echo "$ac_t""$ac_cv_header_time" 1>&6
@@ -2176,28 +2402,29 @@ EOF
 fi
 
 echo $ac_n "checking whether struct tm is in sys/time.h or time.h""... $ac_c" 1>&6
+echo "configure:2406: checking whether struct tm is in sys/time.h or time.h" >&5
 if eval "test \"`echo '$''{'ac_cv_struct_tm'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2184 "configure"
+#line 2411 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 #include <time.h>
-int main() { return 0; }
-int t() {
+int main() {
 struct tm *tp; tp->tm_sec;
 ; return 0; }
 EOF
-if eval $ac_compile; then
+if { (eval echo configure:2419: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_struct_tm=time.h
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   ac_cv_struct_tm=sys/time.h
 fi
 rm -f conftest*
-
 fi
 
 echo "$ac_t""$ac_cv_struct_tm" 1>&6
@@ -2209,28 +2436,29 @@ EOF
 fi
 
 echo $ac_n "checking for tm_zone in struct tm""... $ac_c" 1>&6
+echo "configure:2440: checking for tm_zone in struct tm" >&5
 if eval "test \"`echo '$''{'ac_cv_struct_tm_zone'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2217 "configure"
+#line 2445 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 #include <$ac_cv_struct_tm>
-int main() { return 0; }
-int t() {
+int main() {
 struct tm tm; tm.tm_zone;
 ; return 0; }
 EOF
-if eval $ac_compile; then
+if { (eval echo configure:2453: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_struct_tm_zone=yes
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   ac_cv_struct_tm_zone=no
 fi
 rm -f conftest*
-
 fi
 
 echo "$ac_t""$ac_cv_struct_tm_zone" 1>&6
@@ -2241,30 +2469,31 @@ EOF
 
 else
   echo $ac_n "checking for tzname""... $ac_c" 1>&6
+echo "configure:2473: checking for tzname" >&5
 if eval "test \"`echo '$''{'ac_cv_var_tzname'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2249 "configure"
+#line 2478 "configure"
 #include "confdefs.h"
 #include <time.h>
 #ifndef tzname /* For SGI.  */
 extern char *tzname[]; /* RS6000 and others reject char **tzname.  */
 #endif
-int main() { return 0; }
-int t() {
+int main() {
 atoi(*tzname);
 ; return 0; }
 EOF
-if eval $ac_link; then
+if { (eval echo configure:2488: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest; then
   rm -rf conftest*
   ac_cv_var_tzname=yes
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   ac_cv_var_tzname=no
 fi
 rm -f conftest*
-
 fi
 
 echo "$ac_t""$ac_cv_var_tzname" 1>&6
@@ -2278,13 +2507,14 @@ fi
 
 
 echo $ac_n "checking whether char is unsigned""... $ac_c" 1>&6
+echo "configure:2511: checking whether char is unsigned" >&5
 if eval "test \"`echo '$''{'ac_cv_c_char_unsigned'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   if test "$GCC" = yes; then
   # GCC predefines this symbol on systems where it applies.
 cat > conftest.$ac_ext <<EOF
-#line 2288 "configure"
+#line 2518 "configure"
 #include "confdefs.h"
 #ifdef __CHAR_UNSIGNED__
   yes
@@ -2305,8 +2535,8 @@ else
 if test "$cross_compiling" = yes; then
     { echo "configure: error: can not run test program while cross compiling" 1>&2; exit 1; }
 else
-cat > conftest.$ac_ext <<EOF
-#line 2310 "configure"
+  cat > conftest.$ac_ext <<EOF
+#line 2540 "configure"
 #include "confdefs.h"
 /* volatile prevents gcc2 from optimizing the test away on sparcs.  */
 #if !defined(__STDC__) || __STDC__ != 1
@@ -2316,15 +2546,19 @@ main() {
   volatile char c = 255; exit(c < 0);
 }
 EOF
-eval $ac_link
-if test -s conftest && (./conftest; exit) 2>/dev/null; then
+if { (eval echo configure:2550: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest && (./conftest; exit) 2>/dev/null
+then
   ac_cv_c_char_unsigned=yes
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -fr conftest*
   ac_cv_c_char_unsigned=no
 fi
-fi
 rm -fr conftest*
 fi
+
+fi
 fi
 
 echo "$ac_t""$ac_cv_c_char_unsigned" 1>&6
@@ -2336,15 +2570,15 @@ EOF
 fi
 
 echo $ac_n "checking for working const""... $ac_c" 1>&6
+echo "configure:2574: checking for working const" >&5
 if eval "test \"`echo '$''{'ac_cv_c_const'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2344 "configure"
+#line 2579 "configure"
 #include "confdefs.h"
 
-int main() { return 0; }
-int t() {
+int main() {
 
 /* Ultrix mips cc rejects this.  */
 typedef int charset[2]; const charset x;
@@ -2390,15 +2624,16 @@ ccp = (char const *const *) p;
 
 ; return 0; }
 EOF
-if eval $ac_compile; then
+if { (eval echo configure:2628: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_c_const=yes
 else
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
   rm -rf conftest*
   ac_cv_c_const=no
 fi
 rm -f conftest*
-
 fi
 
 echo "$ac_t""$ac_cv_c_const" 1>&6
@@ -2412,11 +2647,12 @@ fi
 
 
 echo $ac_n "checking for ANSI stringizing capability""... $ac_c" 1>&6
+echo "configure:2651: checking for ANSI stringizing capability" >&5
 if eval "test \"`echo '$''{'gawk_cv_c_stringize'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2420 "configure"
+#line 2656 "configure"
 #include "confdefs.h"
 
 #define x(y) #y
@@ -2463,11 +2699,25 @@ cat > confcache <<\EOF
 # --recheck option to rerun configure.
 #
 EOF
+# The following way of writing the cache mishandles newlines in values,
+# but we know of no workaround that is simple, portable, and efficient.
+# So, don't put newlines in cache variables' values.
 # Ultrix sh set writes to stderr and can't be redirected directly,
 # and sets the high bit in the cache file unless we assign to the vars.
 (set) 2>&1 |
-  sed -n "s/^\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\)=\(.*\)/\1=\${\1='\2'}/p" \
-  >> confcache
+  case `(ac_space=' '; set) 2>&1` in
+  *ac_space=\ *)
+    # `set' does not quote correctly, so add quotes (double-quote substitution
+    # turns \\\\ into \\, and sed turns \\ into \).
+    sed -n \
+      -e "s/'/'\\\\''/g" \
+      -e "s/^\\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\\)=\\(.*\\)/\\1=\${\\1='\\2'}/p"
+    ;;
+  *)
+    # `set' quotes correctly as required by POSIX, so do not add quotes.
+    sed -n -e 's/^\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\)=\(.*\)/\1=${\1=\2}/p'
+    ;;
+  esac >> confcache
 if cmp -s $cache_file confcache; then
   :
 else
@@ -2522,7 +2772,7 @@ do
     echo "running \${CONFIG_SHELL-/bin/sh} $0 $ac_configure_args --no-create --no-recursion"
     exec \${CONFIG_SHELL-/bin/sh} $0 $ac_configure_args --no-create --no-recursion ;;
   -version | --version | --versio | --versi | --vers | --ver | --ve | --v)
-    echo "$CONFIG_STATUS generated by autoconf version 2.7"
+    echo "$CONFIG_STATUS generated by autoconf version 2.12"
     exit 0 ;;
   -help | --help | --hel | --he | --h)
     echo "\$ac_cs_usage"; exit 0 ;;
@@ -2574,20 +2824,56 @@ s%@ALLOCA@%$ALLOCA%g
 
 CEOF
 EOF
+
+cat >> $CONFIG_STATUS <<\EOF
+
+# Split the substitutions into bite-sized pieces for seds with
+# small command number limits, like on Digital OSF/1 and HP-UX.
+ac_max_sed_cmds=90 # Maximum number of lines to put in a sed script.
+ac_file=1 # Number of current file.
+ac_beg=1 # First line for current file.
+ac_end=$ac_max_sed_cmds # Line after last line for current file.
+ac_more_lines=:
+ac_sed_cmds=""
+while $ac_more_lines; do
+  if test $ac_beg -gt 1; then
+    sed "1,${ac_beg}d; ${ac_end}q" conftest.subs > conftest.s$ac_file
+  else
+    sed "${ac_end}q" conftest.subs > conftest.s$ac_file
+  fi
+  if test ! -s conftest.s$ac_file; then
+    ac_more_lines=false
+    rm -f conftest.s$ac_file
+  else
+    if test -z "$ac_sed_cmds"; then
+      ac_sed_cmds="sed -f conftest.s$ac_file"
+    else
+      ac_sed_cmds="$ac_sed_cmds | sed -f conftest.s$ac_file"
+    fi
+    ac_file=`expr $ac_file + 1`
+    ac_beg=$ac_end
+    ac_end=`expr $ac_end + $ac_max_sed_cmds`
+  fi
+done
+if test -z "$ac_sed_cmds"; then
+  ac_sed_cmds=cat
+fi
+EOF
+
 cat >> $CONFIG_STATUS <<EOF
 
 CONFIG_FILES=\${CONFIG_FILES-"Makefile doc/Makefile test/Makefile awklib/Makefile"}
 EOF
 cat >> $CONFIG_STATUS <<\EOF
 for ac_file in .. $CONFIG_FILES; do if test "x$ac_file" != x..; then
-  # Support "outfile[:infile]", defaulting infile="outfile.in".
+  # Support "outfile[:infile[:infile...]]", defaulting infile="outfile.in".
   case "$ac_file" in
-  *:*) ac_file_in=`echo "$ac_file"|sed 's%.*:%%'`
+  *:*) ac_file_in=`echo "$ac_file"|sed 's%[^:]*:%%'`
        ac_file=`echo "$ac_file"|sed 's%:.*%%'` ;;
   *) ac_file_in="${ac_file}.in" ;;
   esac
 
-  # Adjust relative srcdir, etc. for subdirectories.
+  # Adjust a relative srcdir, top_srcdir, and INSTALL for subdirectories.
 
   # Remove last slash and all that follows it.  Not all systems have dirname.
   ac_dir=`echo $ac_file|sed 's%/[^/][^/]*$%%'`
@@ -2615,6 +2901,7 @@ for ac_file in .. $CONFIG_FILES; do if test "x$ac_file" != x..; then
   [/$]*) INSTALL="$ac_given_INSTALL" ;;
   *) INSTALL="$ac_dots$ac_given_INSTALL" ;;
   esac
+
   echo creating "$ac_file"
   rm -f "$ac_file"
   configure_input="Generated automatically from `echo $ac_file_in|sed 's%.*/%%'` by configure."
@@ -2623,14 +2910,16 @@ for ac_file in .. $CONFIG_FILES; do if test "x$ac_file" != x..; then
 # $configure_input" ;;
   *) ac_comsub= ;;
   esac
+
+  ac_file_inputs=`echo $ac_file_in|sed -e "s%^%$ac_given_srcdir/%" -e "s%:% $ac_given_srcdir/%g"`
   sed -e "$ac_comsub
 s%@configure_input@%$configure_input%g
 s%@srcdir@%$srcdir%g
 s%@top_srcdir@%$top_srcdir%g
 s%@INSTALL@%$INSTALL%g
-" -f conftest.subs $ac_given_srcdir/$ac_file_in > $ac_file
+" $ac_file_inputs | (eval "$ac_sed_cmds") > $ac_file
 fi; done
-rm -f conftest.subs
+rm -f conftest.s*
 
 # These sed commands are passed to sed as "A NAME B NAME C VALUE D", where
 # NAME is the cpp macro being defined and VALUE is the value it is being given.
@@ -2651,11 +2940,17 @@ ac_eB='$%\1#\2define\3'
 ac_eC=' '
 ac_eD='%g'
 
-CONFIG_HEADERS=${CONFIG_HEADERS-"config.h:configh.in"}
+if test "${CONFIG_HEADERS+set}" != set; then
+EOF
+cat >> $CONFIG_STATUS <<EOF
+  CONFIG_HEADERS="config.h:configh.in"
+EOF
+cat >> $CONFIG_STATUS <<\EOF
+fi
 for ac_file in .. $CONFIG_HEADERS; do if test "x$ac_file" != x..; then
-  # Support "outfile[:infile]", defaulting infile="outfile.in".
+  # Support "outfile[:infile[:infile...]]", defaulting infile="outfile.in".
   case "$ac_file" in
-  *:*) ac_file_in=`echo "$ac_file"|sed 's%.*:%%'`
+  *:*) ac_file_in=`echo "$ac_file"|sed 's%[^:]*:%%'`
        ac_file=`echo "$ac_file"|sed 's%:.*%%'` ;;
   *) ac_file_in="${ac_file}.in" ;;
   esac
@@ -2663,7 +2958,8 @@ for ac_file in .. $CONFIG_HEADERS; do if test "x$ac_file" != x..; then
   echo creating $ac_file
 
   rm -f conftest.frag conftest.in conftest.out
-  cp $ac_given_srcdir/$ac_file_in conftest.in
+  ac_file_inputs=`echo $ac_file_in|sed -e "s%^%$ac_given_srcdir/%" -e "s%:% $ac_given_srcdir/%g"`
+  cat $ac_file_inputs > conftest.in
 
 EOF
 
@@ -2675,7 +2971,7 @@ rm -f conftest.vals
 cat > conftest.hdr <<\EOF
 s/[\\&%]/\\&/g
 s%[\\$`]%\\&%g
-s%#define \([A-Za-z_][A-Za-z0-9_]*\) \(.*\)%${ac_dA}\1${ac_dB}\1${ac_dC}\2${ac_dD}%gp
+s%#define \([A-Za-z_][A-Za-z0-9_]*\) *\(.*\)%${ac_dA}\1${ac_dB}\1${ac_dC}\2${ac_dD}%gp
 s%ac_d%ac_u%gp
 s%ac_u%ac_e%gp
 EOF
@@ -2691,8 +2987,6 @@ EOF
 
 # Break up conftest.vals because some shells have a limit on
 # the size of here documents, and old seds have small limits too.
-# Maximum number of lines to put in a single here document.
-ac_max_here_lines=12
 
 rm -f conftest.tail
 while :
@@ -2723,12 +3017,22 @@ cat >> $CONFIG_STATUS <<\EOF
     echo "$ac_file is unchanged"
     rm -f conftest.h
   else
+    # Remove last slash and all that follows it.  Not all systems have dirname.
+      ac_dir=`echo $ac_file|sed 's%/[^/][^/]*$%%'`
+      if test "$ac_dir" != "$ac_file" && test "$ac_dir" != .; then
+      # The file is in a subdirectory.
+      test ! -d "$ac_dir" && mkdir "$ac_dir"
+    fi
     rm -f $ac_file
     mv conftest.h $ac_file
   fi
 fi; done
 
+EOF
+cat >> $CONFIG_STATUS <<EOF
 
+EOF
+cat >> $CONFIG_STATUS <<\EOF
 date > stamp-h
 exit 0
 EOF
diff --git a/configure.in b/configure.in
index c92e6425..c5a9661c 100644
--- a/configure.in
+++ b/configure.in
@@ -28,7 +28,7 @@ dnl define(AC_CONFIG_AUX_DIR,)
 
 dnl This is the configure.in script proper
 AC_INIT(awk.h)
-AC_PREREQ(2.7)
+AC_PREREQ(2.12)
 AC_CONFIG_HEADER(config.h:configh.in)
 
 dnl checks for programs
@@ -62,9 +62,6 @@ AC_AIX
 AC_ISC_POSIX
 AC_MINIX
 
-dnl see if the C compiler really works
-AM_SANITY_CHECK_CC
-
 dnl checks for header files
 AC_HEADER_STDC
 AC_HEADER_SYS_WAIT
diff --git a/custom.h b/custom.h
index 57f2724d..e26a55b5 100644
--- a/custom.h
+++ b/custom.h
@@ -40,6 +40,8 @@
 /* for VMS POSIX, from Pat Rankin, rankin@eql.caltech.edu */
 #ifdef VMS_POSIX
 #undef VMS
+#define GETPGRP_VOID	/* autoconf's test for this tries to use
+			   `setpgrp()', which doesn't exist.  */
 #include "vms/redirect.h"
 #endif
 
diff --git a/doc/ChangeLog b/doc/ChangeLog
index ee017484..e07d69b1 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,23 @@
+Wed Dec 25 11:25:22 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.2: Release tar file made.
+
+Wed Dec 25 11:17:32 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Makefile.in ($(mandir)/igawk$(manext),$(mandir)/gawk$(manext)):
+	  remove chmod command; let $(INSTALL_DATA) use -m.
+
+Tue Dec 17 22:38:28 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Makefile.in (gawk.info,gawk.dvi,postscript): run makeinfo, TeX,
+	  and/or troff against files in $(srcdir). Thanks to Ulrich Drepper.
+	  ($(infodir)/gawk.info): use --info-dir to install-info, not
+	  --infodir.
+
+Tue Dec 10 23:09:26 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.1: Release tar file made.
+
 Mon Dec  9 12:48:54 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
 
 	* no.colors: new file from Michal for old troffs.
diff --git a/doc/Makefile.in b/doc/Makefile.in
index d634020e..52ecc76d 100644
--- a/doc/Makefile.in
+++ b/doc/Makefile.in
@@ -78,14 +78,14 @@ $(infodir)/gawk.info: gawk.info
 		$(INSTALL_DATA) $$i $(infodir)/$i ; \
 	done; \
 	if $(SHELL) -c 'install-info --version' > /dev/null 2>&1 ; \
-	then install-info --infodir=$(infodir) gawk.info ; \
+	then install-info --info-dir=$(infodir) gawk.info ; \
 	else true ; fi
 
 $(mandir)/gawk$(manext): gawk.1
-	$(INSTALL_DATA) $(srcdir)/gawk.1 $(mandir)/gawk$(manext) && chmod 644 $(mandir)/gawk$(manext)
+	$(INSTALL_DATA) $(srcdir)/gawk.1 $(mandir)/gawk$(manext)
 
 $(mandir)/igawk$(manext): igawk.1
-	$(INSTALL_DATA) $(srcdir)/igawk.1 $(mandir)/igawk$(manext) && chmod 644 $(mandir)/igawk$(manext)
+	$(INSTALL_DATA) $(srcdir)/igawk.1 $(mandir)/igawk$(manext)
 
 uninstall:
 	rm -f $(mandir)/gawk$(manext) $(mandir)/igawk$(manext) $(infodir)/gawk.info*
@@ -93,18 +93,18 @@ uninstall:
 dvi:	gawk.dvi
 
 gawk.dvi: gawk.texi
-	-TEXINPUTS=$$TEXINPUTS:$(srcdir) $(TEXI2DVI) gawk.texi
+	-TEXINPUTS=$$TEXINPUTS:$(srcdir) $(TEXI2DVI) $(srcdir)/gawk.texi
 	texindex gawk.??
-	TEXINPUTS=$$TEXINPUTS:$(srcdir) $(TEX) gawk.texi
+	TEXINPUTS=$$TEXINPUTS:$(srcdir) $(TEX) $(srcdir)/gawk.texi
 
 info:	gawk.info
 
 gawk.info: gawk.texi
-	$(MAKEINFO) gawk.texi
+	$(MAKEINFO) $(srcdir)/gawk.texi
 
 postscript: dvi gawk.1 igawk.1 $(AWKCARD)
-	-groff -man gawk.1 > gawk.1.ps
-	-groff -man igawk.1 > igawk.1.ps
+	-groff -man $(srcdir)/gawk.1 > gawk.1.ps
+	-groff -man $(srcdir)/igawk.1 > igawk.1.ps
 	dvips -o gawk.ps gawk.dvi
 
 awkcard.tr: awkcard.in
diff --git a/doc/awkcard.in b/doc/awkcard.in
index 50af4aae..b68f01d8 100644
--- a/doc/awkcard.in
+++ b/doc/awkcard.in
@@ -204,7 +204,7 @@ forms are for full POSIX compliance.
 \*(FC\-\^\-copyleft\*(FR
 \*(FC\-\^\-copyright\*(FR
 \*(FC\-W copyleft\*(FR
-\*(FC\-W copyright\*(FR			print the short version of the GNU
+\*(FC\-W copyright\*(FR		print the short version of the GNU
 				copyright information on \*(FCstdout\*(FR
 \*(FC\-\^\-help\*(FR
 \*(FC\-\^\-usage\*(FR
@@ -1318,7 +1318,7 @@ has been specified.\*(CB
 .ES
 .nf
 \*(CDHost: \*(FCftp.gnu.ai.mit.edu\*(FR
-File: \*(FC/pub/gnu/gawk-3.0.1.tar.gz\fP
+File: \*(FC/pub/gnu/gawk-3.0.2.tar.gz\fP
 	GNU \*(AK (\*(GK). There may be a later version
 .sp .5
 Host: \*(FCnetlib.bell-labs.com\*(FR
diff --git a/doc/gawk.1 b/doc/gawk.1
index 44ac8c19..0568c168 100644
--- a/doc/gawk.1
+++ b/doc/gawk.1
@@ -1,7 +1,7 @@
 .ds PX \s-1POSIX\s+1
 .ds UX \s-1UNIX\s+1
 .ds AN \s-1ANSI\s+1
-.TH GAWK 1 "Dec 09 1996" "Free Software Foundation" "Utility Commands"
+.TH GAWK 1 "Dec 19 1996" "Free Software Foundation" "Utility Commands"
 .SH NAME
 gawk \- pattern scanning and processing language
 .SH SYNOPSIS
@@ -2535,7 +2535,7 @@ and the effort to do so really is not worth it.
 .SH VERSION INFORMATION
 This man page documents
 .IR gawk ,
-version 3.0.1.
+version 3.0.2.
 .SH AUTHORS
 The original version of \*(UX
 .I awk
diff --git a/doc/gawk.info b/doc/gawk.info
new file mode 100644
index 00000000..680fbab3
--- /dev/null
+++ b/doc/gawk.info
@@ -0,0 +1,18232 @@
+This is gawk.info, produced by makeinfo version 4.0 from gawk.texi.
+
+INFO-DIR-SECTION Programming Languages
+START-INFO-DIR-ENTRY
+* Gawk: (gawk.info).           A Text Scanning and Processing Language.
+END-INFO-DIR-ENTRY
+
+   This file documents `awk', a program that you can use to select
+particular records in a file and perform operations upon them.
+
+   This is Edition 1.0.1 of `The GNU Awk User's Guide', for the
+3.0.1 version of the GNU implementation of AWK.
+
+   Copyright (C) 1989, 1991, 92, 93, 96 Free Software Foundation, Inc.
+
+   Permission is granted to make and distribute verbatim copies of this
+manual provided the copyright notice and this permission notice are
+preserved on all copies.
+
+   Permission is granted to copy and distribute modified versions of
+this manual under the conditions for verbatim copying, provided that
+the entire resulting derived work is distributed under the terms of a
+permission notice identical to this one.
+
+   Permission is granted to copy and distribute translations of this
+manual into another language, under the above conditions for modified
+versions, except that this permission notice may be stated in a
+translation approved by the Foundation.
+
+
+File: gawk.info,  Node: Top,  Next: Preface,  Prev: (dir),  Up: (dir)
+
+General Introduction
+********************
+
+   This file documents `awk', a program that you can use to select
+particular records in a file and perform operations upon them.
+
+   This is Edition 1.0.1 of `The GNU Awk User's Guide',
+for the 3.0.1 version of the GNU implementation
+of AWK.
+
+* Menu:
+
+* Preface::                     What this Info file is about; brief
+                                history and acknowledgements.
+* What Is Awk::                 What is the `awk' language; using this
+                                Info file.
+* Getting Started::             A basic introduction to using `awk'. How
+                                to run an `awk' program. Command line
+                                syntax.
+* One-liners::                  Short, sample `awk' programs.
+* Regexp::                      All about matching things using regular
+                                expressions.
+* Reading Files::               How to read files and manipulate fields.
+* Printing::                    How to print using `awk'.  Describes the
+                                `print' and `printf' statements.
+                                Also describes redirection of output.
+* Expressions::                 Expressions are the basic building blocks of
+                                statements.
+* Patterns and Actions::        Overviews of patterns and actions.
+* Statements::                  The various control statements are described
+                                in detail.
+* Built-in Variables::          Built-in Variables
+* Arrays::                      The description and use of arrays. Also
+                                includes array-oriented control statements.
+* Built-in::                    The built-in functions are summarized here.
+* User-defined::                User-defined functions are described in
+                                detail.
+* Invoking Gawk::               How to run `gawk'.
+* Library Functions::           A Library of `awk' Functions.
+* Sample Programs::             Many `awk' programs with complete
+                                explanations.
+* Language History::            The evolution of the `awk' language.
+* Gawk Summary::                `gawk' Options and Language Summary.
+* Installation::                Installing `gawk' under various operating
+                                systems.
+* Notes::                       Something about the implementation of
+                                `gawk'.
+* Glossary::                    An explanation of some unfamiliar terms.
+* Copying::                     Your right to copy and distribute `gawk'.
+* Index::                       Concept and Variable Index.
+
+* History::                     The history of `gawk' and `awk'.
+* Manual History::              Brief history of the GNU project and this
+                                Info file.
+* Acknowledgements::            Acknowledgements.
+* This Manual::                 Using this Info file. Includes sample
+                                input files that you can use.
+* Conventions::                 Typographical Conventions.
+* Sample Data Files::           Sample data files for use in the `awk'
+                                programs illustrated in this Info file.
+* Names::                       What name to use to find `awk'.
+* Running gawk::                How to run `gawk' programs; includes
+                                command line syntax.
+* One-shot::                    Running a short throw-away `awk' program.
+* Read Terminal::               Using no input files (input from terminal
+                                instead).
+* Long::                        Putting permanent `awk' programs in
+                                files.
+* Executable Scripts::          Making self-contained `awk' programs.
+* Comments::                    Adding documentation to `gawk' programs.
+* Very Simple::                 A very simple example.
+* Two Rules::                   A less simple one-line example with two rules.
+* More Complex::                A more complex example.
+* Statements/Lines::            Subdividing or combining statements into
+                                lines.
+* Other Features::              Other Features of `awk'.
+* When::                        When to use `gawk' and when to use other
+                                things.
+* Regexp Usage::                How to Use Regular Expressions.
+* Escape Sequences::            How to write non-printing characters.
+* Regexp Operators::            Regular Expression Operators.
+* GNU Regexp Operators::        Operators specific to GNU software.
+* Case-sensitivity::            How to do case-insensitive matching.
+* Leftmost Longest::            How much text matches.
+* Computed Regexps::            Using Dynamic Regexps.
+* Records::                     Controlling how data is split into records.
+* Fields::                      An introduction to fields.
+* Non-Constant Fields::         Non-constant Field Numbers.
+* Changing Fields::             Changing the Contents of a Field.
+* Field Separators::            The field separator and how to change it.
+* Basic Field Splitting::       How fields are split with single characters or
+                                simple strings.
+* Regexp Field Splitting::      Using regexps as the field separator.
+* Single Character Fields::     Making each character a separate field.
+* Command Line Field Separator:: Setting `FS' from the command line.
+* Field Splitting Summary::     Some final points and a summary table.
+* Constant Size::               Reading constant width data.
+* Multiple Line::               Reading multi-line records.
+* Getline::                     Reading files under explicit program control
+                                using the `getline' function.
+* Getline Intro::               Introduction to the `getline' function.
+* Plain Getline::               Using `getline' with no arguments.
+* Getline/Variable::            Using `getline' into a variable.
+* Getline/File::                Using `getline' from a file.
+* Getline/Variable/File::       Using `getline' into a variable from a
+                                file.
+* Getline/Pipe::                Using `getline' from a pipe.
+* Getline/Variable/Pipe::       Using `getline' into a variable from a
+                                pipe.
+* Getline Summary::             Summary Of `getline' Variants.
+* Print::                       The `print' statement.
+* Print Examples::              Simple examples of `print' statements.
+* Output Separators::           The output separators and how to change them.
+* OFMT::                        Controlling Numeric Output With `print'.
+* Printf::                      The `printf' statement.
+* Basic Printf::                Syntax of the `printf' statement.
+* Control Letters::             Format-control letters.
+* Format Modifiers::            Format-specification modifiers.
+* Printf Examples::             Several examples.
+* Redirection::                 How to redirect output to multiple files and
+                                pipes.
+* Special Files::               File name interpretation in `gawk'.
+                                `gawk' allows access to inherited file
+                                descriptors.
+* Close Files And Pipes::       Closing Input and Output Files and Pipes.
+* Constants::                   String, numeric, and regexp constants.
+* Scalar Constants::            Numeric and string constants.
+* Regexp Constants::            Regular Expression constants.
+* Using Constant Regexps::      When and how to use a regexp constant.
+* Variables::                   Variables give names to values for later use.
+* Using Variables::             Using variables in your programs.
+* Assignment Options::          Setting variables on the command line and a
+                                summary of command line syntax. This is an
+                                advanced method of input.
+* Conversion::                  The conversion of strings to numbers and vice
+                                versa.
+* Arithmetic Ops::              Arithmetic operations (`+', `-',
+                                etc.)
+* Concatenation::               Concatenating strings.
+* Assignment Ops::              Changing the value of a variable or a field.
+* Increment Ops::               Incrementing the numeric value of a variable.
+* Truth Values::                What is ``true'' and what is ``false''.
+* Typing and Comparison::       How variables acquire types, and how this
+                                affects comparison of numbers and strings with
+                                `<', etc.
+* Boolean Ops::                 Combining comparison expressions using boolean
+                                operators `||' (``or''), `&&'
+                                (``and'') and `!' (``not'').
+* Conditional Exp::             Conditional expressions select between two
+                                subexpressions under control of a third
+                                subexpression.
+* Function Calls::              A function call is an expression.
+* Precedence::                  How various operators nest.
+* Pattern Overview::            What goes into a pattern.
+* Kinds of Patterns::           A list of all kinds of patterns.
+* Regexp Patterns::             Using regexps as patterns.
+* Expression Patterns::         Any expression can be used as a pattern.
+* Ranges::                      Pairs of patterns specify record ranges.
+* BEGIN/END::                   Specifying initialization and cleanup rules.
+* Using BEGIN/END::             How and why to use BEGIN/END rules.
+* I/O And BEGIN/END::           I/O issues in BEGIN/END rules.
+* Empty::                       The empty pattern, which matches every record.
+* Action Overview::             What goes into an action.
+* If Statement::                Conditionally execute some `awk'
+                                statements.
+* While Statement::             Loop until some condition is satisfied.
+* Do Statement::                Do specified action while looping until some
+                                condition is satisfied.
+* For Statement::               Another looping statement, that provides
+                                initialization and increment clauses.
+* Break Statement::             Immediately exit the innermost enclosing loop.
+* Continue Statement::          Skip to the end of the innermost enclosing
+                                loop.
+* Next Statement::              Stop processing the current input record.
+* Nextfile Statement::          Stop processing the current file.
+* Exit Statement::              Stop execution of `awk'.
+* User-modified::               Built-in variables that you change to control
+                                `awk'.
+* Auto-set::                    Built-in variables where `awk' gives you
+                                information.
+* ARGC and ARGV::               Ways to use `ARGC' and `ARGV'.
+* Array Intro::                 Introduction to Arrays
+* Reference to Elements::       How to examine one element of an array.
+* Assigning Elements::          How to change an element of an array.
+* Array Example::               Basic Example of an Array
+* Scanning an Array::           A variation of the `for' statement. It
+                                loops through the indices of an array's
+                                existing elements.
+* Delete::                      The `delete' statement removes an element
+                                from an array.
+* Numeric Array Subscripts::    How to use numbers as subscripts in
+                                `awk'.
+* Uninitialized Subscripts::    Using Uninitialized variables as subscripts.
+* Multi-dimensional::           Emulating multi-dimensional arrays in
+                                `awk'.
+* Multi-scanning::              Scanning multi-dimensional arrays.
+* Calling Built-in::            How to call built-in functions.
+* Numeric Functions::           Functions that work with numbers, including
+                                `int', `sin' and `rand'.
+* String Functions::            Functions for string manipulation, such as
+                                `split', `match', and
+                                `sprintf'.
+* I/O Functions::               Functions for files and shell commands.
+* Time Functions::              Functions for dealing with time stamps.
+* Definition Syntax::           How to write definitions and what they mean.
+* Function Example::            An example function definition and what it
+                                does.
+* Function Caveats::            Things to watch out for.
+* Return Statement::            Specifying the value a function returns.
+* Options::                     Command line options and their meanings.
+* Other Arguments::             Input file names and variable assignments.
+* AWKPATH Variable::            Searching directories for `awk' programs.
+* Obsolete::                    Obsolete Options and/or features.
+* Undocumented::                Undocumented Options and Features.
+* Known Bugs::                  Known Bugs in `gawk'.
+* Portability Notes::           What to do if you don't have `gawk'.
+* Nextfile Function::           Two implementations of a `nextfile'
+                                function.
+* Assert Function::             A function for assertions in `awk'
+                                programs.
+* Round Function::              A function for rounding if `sprintf' does
+                                not do it correctly.
+* Ordinal Functions::           Functions for using characters as numbers and
+                                vice versa.
+* Join Function::               A function to join an array into a string.
+* Mktime Function::             A function to turn a date into a timestamp.
+* Gettimeofday Function::       A function to get formatted times.
+* Filetrans Function::          A function for handling data file transitions.
+* Getopt Function::             A function for processing command line
+                                arguments.
+* Passwd Functions::            Functions for getting user information.
+* Group Functions::             Functions for getting group information.
+* Library Names::               How to best name private global variables in
+                                library functions.
+* Clones::                      Clones of common utilities.
+* Cut Program::                 The `cut' utility.
+* Egrep Program::               The `egrep' utility.
+* Id Program::                  The `id' utility.
+* Split Program::               The `split' utility.
+* Tee Program::                 The `tee' utility.
+* Uniq Program::                The `uniq' utility.
+* Wc Program::                  The `wc' utility.
+* Miscellaneous Programs::      Some interesting `awk' programs.
+* Dupword Program::             Finding duplicated words in a document.
+* Alarm Program::               An alarm clock.
+* Translate Program::           A program similar to the `tr' utility.
+* Labels Program::              Printing mailing labels.
+* Word Sorting::                A program to produce a word usage count.
+* History Sorting::             Eliminating duplicate entries from a history
+                                file.
+* Extract Program::             Pulling out programs from Texinfo source
+                                files.
+* Simple Sed::                  A Simple Stream Editor.
+* Igawk Program::               A wrapper for `awk' that includes files.
+* V7/SVR3.1::                   The major changes between V7 and System V
+                                Release 3.1.
+* SVR4::                        Minor changes between System V Releases 3.1
+                                and 4.
+* POSIX::                       New features from the POSIX standard.
+* BTL::                         New features from the Bell Laboratories
+                                version of `awk'.
+* POSIX/GNU::                   The extensions in `gawk' not in POSIX
+                                `awk'.
+* Command Line Summary::        Recapitulation of the command line.
+* Language Summary::            A terse review of the language.
+* Variables/Fields::            Variables, fields, and arrays.
+* Fields Summary::              Input field splitting.
+* Built-in Summary::            `awk''s built-in variables.
+* Arrays Summary::              Using arrays.
+* Data Type Summary::           Values in `awk' are numbers or strings.
+* Rules Summary::               Patterns and Actions, and their component
+                                parts.
+* Pattern Summary::             Quick overview of patterns.
+* Regexp Summary::              Quick overview of regular expressions.
+* Actions Summary::             Quick overview of actions.
+* Operator Summary::            `awk' operators.
+* Control Flow Summary::        The control statements.
+* I/O Summary::                 The I/O statements.
+* Printf Summary::              A summary of `printf'.
+* Special File Summary::        Special file names interpreted internally.
+* Built-in Functions Summary::  Built-in numeric and string functions.
+* Time Functions Summary::      Built-in time functions.
+* String Constants Summary::    Escape sequences in strings.
+* Functions Summary::           Defining and calling functions.
+* Historical Features::         Some undocumented but supported ``features''.
+* Gawk Distribution::           What is in the `gawk' distribution.
+* Getting::                     How to get the distribution.
+* Extracting::                  How to extract the distribution.
+* Distribution contents::       What is in the distribution.
+* Unix Installation::           Installing `gawk' under various versions
+                                of Unix.
+* Quick Installation::          Compiling `gawk' under Unix.
+* Configuration Philosophy::    How it's all supposed to work.
+* VMS Installation::            Installing `gawk' on VMS.
+* VMS Compilation::             How to compile `gawk' under VMS.
+* VMS Installation Details::    How to install `gawk' under VMS.
+* VMS Running::                 How to run `gawk' under VMS.
+* VMS POSIX::                   Alternate instructions for VMS POSIX.
+* PC Installation::             Installing and Compiling `gawk' on MS-DOS
+                                and OS/2
+* Atari Installation::          Installing `gawk' on the Atari ST.
+* Atari Compiling::             Compiling `gawk' on Atari
+* Atari Using::                 Running `gawk' on Atari
+* Amiga Installation::          Installing `gawk' on an Amiga.
+* Bugs::                        Reporting Problems and Bugs.
+* Other Versions::              Other freely available `awk'
+                                implementations.
+* Compatibility Mode::          How to disable certain `gawk' extensions.
+* Additions::                   Making Additions To `gawk'.
+* Adding Code::                 Adding code to the main body of `gawk'.
+* New Ports::                   Porting `gawk' to a new operating system.
+* Future Extensions::           New features that may be implemented one day.
+* Improvements::                Suggestions for improvements by volunteers.
+
+                  To Miriam, for making me complete.
+
+
+                  To Chana, for the joy you bring us.
+
+
+                To Rivka, for the exponential increase.
+
+
+                  To Nachum, for the added dimension.
+
+
+File: gawk.info,  Node: Preface,  Next: What Is Awk,  Prev: Top,  Up: Top
+
+Preface
+*******
+
+   This Info file teaches you about the `awk' language and how you can
+use it effectively.  You should already be familiar with basic system
+commands, such as `cat' and `ls',(1) and basic shell facilities, such
+as Input/Output (I/O) redirection and pipes.
+
+   Implementations of the `awk' language are available for many
+different computing environments.  This Info file, while describing the
+`awk' language in general, also describes a particular implementation
+of `awk' called `gawk' (which stands for "GNU Awk").  `gawk' runs on a
+broad range of Unix systems, ranging from 80386 PC-based computers, up
+through large scale systems, such as Crays. `gawk' has also been ported
+to MS-DOS and OS/2 PC's, Atari and Amiga micro-computers, and VMS.
+
+* Menu:
+
+* History::                     The history of `gawk' and `awk'.
+* Manual History::              Brief history of the GNU project and this
+                                Info file.
+* Acknowledgements::            Acknowledgements.
+
+   ---------- Footnotes ----------
+
+   (1) These commands are available on POSIX compliant systems, as well
+as on traditional Unix based systems. If you are using some other
+operating system, you still need to be familiar with the ideas of I/O
+redirection and pipes.
+
+
+File: gawk.info,  Node: History,  Next: Manual History,  Prev: Preface,  Up: Preface
+
+History of `awk' and `gawk'
+===========================
+
+   The name `awk' comes from the initials of its designers: Alfred V.
+Aho, Peter J. Weinberger, and Brian W. Kernighan.  The original version
+of `awk' was written in 1977 at AT&T Bell Laboratories.  In 1985 a new
+version made the programming language more powerful, introducing
+user-defined functions, multiple input streams, and computed regular
+expressions.  This new version became generally available with Unix
+System V Release 3.1.  The version in System V Release 4 added some new
+features and also cleaned up the behavior in some of the "dark corners"
+of the language.  The specification for `awk' in the POSIX Command
+Language and Utilities standard further clarified the language based on
+feedback from both the `gawk' designers, and the original Bell Labs
+`awk' designers.
+
+   The GNU implementation, `gawk', was written in 1986 by Paul Rubin
+and Jay Fenlason, with advice from Richard Stallman.  John Woods
+contributed parts of the code as well.  In 1988 and 1989, David
+Trueman, with help from Arnold Robbins, thoroughly reworked `gawk' for
+compatibility with the newer `awk'.  Current development focuses on bug
+fixes, performance improvements, standards compliance, and
+occasionally, new features.
+
+
+File: gawk.info,  Node: Manual History,  Next: Acknowledgements,  Prev: History,  Up: Preface
+
+The GNU Project and This Book
+=============================
+
+   The Free Software Foundation (FSF) is a non-profit organization
+dedicated to the production and distribution of freely distributable
+software.  It was founded by Richard M. Stallman, the author of the
+original Emacs editor.  GNU Emacs is the most widely used version of
+Emacs today.
+
+   The GNU project is an on-going effort on the part of the Free
+Software Foundation to create a complete, freely distributable, POSIX
+compliant computing environment.  (GNU stands for "GNU's not Unix".)
+The FSF uses the "GNU General Public License" (or GPL) to ensure that
+source code for their software is always available to the end user. A
+copy of the GPL is included for your reference (*note GNU GENERAL
+PUBLIC LICENSE: Copying.).  The GPL applies to the C language source
+code for `gawk'.
+
+   As of this writing (1995), the only major component of the GNU
+environment still uncompleted is the operating system kernel, and work
+proceeds apace on that.  A shell, an editor (Emacs), highly portable
+optimizing C, C++, and Objective-C compilers, a symbolic debugger, and
+dozens of large and small utilities (such as `gawk'), have all been
+completed and are freely available.
+
+   Until the GNU operating system is released, the FSF recommends the
+use of Linux, a freely distributable, Unix-like operating system for
+80386 and other systems.  There are many books on Linux. One freely
+available one is `Linux Installation and Getting Started', by Matt
+Welsh.  Many Linux distributions are available, often in computer
+stores or bundled on CD-ROM with books about Linux. Also, the FSF
+provides a Linux distribution ("Debian"); contact them for more
+information.  *Note Getting the `gawk' Distribution: Getting, for the
+FSF's contact information.  (There are two other freely available,
+Unix-like operating systems for 80386 and other systems, NetBSD and
+FreeBSD. Both are based on the 4.4-Lite Berkeley Software Distribution,
+and both use recent versions of `gawk' for their versions of `awk'.)
+
+   This Info file itself has gone through several previous, preliminary
+editions.  I started working on a preliminary draft of `The GAWK
+Manual', by Diane Close, Paul Rubin, and Richard Stallman in the fall
+of 1988.  It was around 90 pages long, and barely described the
+original, "old" version of `awk'. After substantial revision, the first
+version of the `The GAWK Manual' to be released was Edition 0.11 Beta in
+October of 1989.  The manual then underwent more substantial revision
+for Edition 0.13 of December 1991.  David Trueman, Pat Rankin, and
+Michal Jaegermann contributed sections of the manual for Edition 0.13.
+That edition was published by the FSF as a bound book early in 1992.
+Since then there have been several minor revisions, notably Edition
+0.14 of November 1992 that was published by the FSF in January of 1993,
+and Edition 0.16 of August 1993.
+
+   Edition 1.0 of `The GNU Awk User's Guide' represents a significant
+re-working of `The GAWK Manual', with much additional material.  The
+FSF and I agree that I am now the primary author.  I also felt that it
+needed a more descriptive title.
+
+   `The GNU Awk User's Guide' will undoubtedly continue to evolve.  An
+electronic version comes with the `gawk' distribution from the FSF.  If
+you find an error in this Info file, please report it!  *Note Reporting
+Problems and Bugs: Bugs, for information on submitting problem reports
+electronically, or write to me in care of the FSF.
+
+
+File: gawk.info,  Node: Acknowledgements,  Prev: Manual History,  Up: Preface
+
+Acknowledgements
+================
+
+   I would like to acknowledge Richard M. Stallman, for his vision of a
+better world, and for his courage in founding the FSF and starting the
+GNU project.
+
+   The initial draft of `The GAWK Manual' had the following
+acknowledgements:
+
+     Many people need to be thanked for their assistance in producing
+     this manual.  Jay Fenlason contributed many ideas and sample
+     programs.  Richard Mlynarik and Robert Chassell gave helpful
+     comments on drafts of this manual.  The paper `A Supplemental
+     Document for `awk'' by John W.  Pierce of the Chemistry Department
+     at UC San Diego, pinpointed several issues relevant both to `awk'
+     implementation and to this manual, that would otherwise have
+     escaped us.
+
+   The following people provided many helpful comments on Edition 0.13
+of `The GAWK Manual': Rick Adams, Michael Brennan, Rich Burridge, Diane
+Close, Christopher ("Topher") Eliot, Michael Lijewski, Pat Rankin,
+Miriam Robbins, and Michal Jaegermann.
+
+   The following people provided many helpful comments for Edition 1.0
+of `The GNU Awk User's Guide': Karl Berry, Michael Brennan, Darrel
+Hankerson, Michal Jaegermann, Michael Lijewski, and Miriam Robbins.
+Pat Rankin, Michal Jaegermann, Darrel Hankerson and Scott Deifik
+updated their respective sections for Edition 1.0.
+
+   Robert J. Chassell provided much valuable advice on the use of
+Texinfo.  He also deserves special thanks for convincing me _not_ to
+title this Info file `How To Gawk Politely'.  Karl Berry helped
+significantly with the TeX part of Texinfo.
+
+   David Trueman deserves special credit; he has done a yeoman job of
+evolving `gawk' so that it performs well, and without bugs.  Although
+he is no longer involved with `gawk', working with him on this project
+was a significant pleasure.
+
+   Scott Deifik, Darrel Hankerson, Kai Uwe Rommel, Pat Rankin, and
+Michal Jaegermann (in no particular order) are long time members of the
+`gawk' "crack portability team."  Without their hard work and help,
+`gawk' would not be nearly the fine program it is today.  It has been
+and continues to be a pleasure working with this team of fine people.
+
+   Jeffrey Friedl provided invaluable help in tracking down a number of
+last minute problems with regular expressions in `gawk' 3.0.
+
+   David and I would like to thank Brian Kernighan of Bell Labs for
+invaluable assistance during the testing and debugging of `gawk', and
+for help in clarifying numerous points about the language.  We could
+not have done nearly as good a job on either `gawk' or its
+documentation without his help.
+
+   I would like to thank Marshall and Elaine Hartholz of Seattle, and
+Dr.  Bert and Rita Schreiber of Detroit for large amounts of quiet
+vacation time in their homes, which allowed me to make significant
+progress on this Info file and on `gawk' itself.  Phil Hughes of SSC
+contributed in a very important way by loaning me his laptop Linux
+system, not once, but twice, allowing me to do a lot of work while away
+from home.
+
+   Finally, I must thank my wonderful wife, Miriam, for her patience
+through the many versions of this project, for her proof-reading, and
+for sharing me with the computer.  I would like to thank my parents for
+their love, and for the grace with which they raised and educated me.
+I also must acknowledge my gratitude to G-d, for the many opportunities
+He has sent my way, as well as for the gifts He has given me with which
+to take advantage of those opportunities.
+
+
+
+Arnold Robbins
+Atlanta, Georgia
+January, 1996
+
+
+File: gawk.info,  Node: What Is Awk,  Next: Getting Started,  Prev: Preface,  Up: Top
+
+Introduction
+************
+
+   If you are like many computer users, you would frequently like to
+make changes in various text files wherever certain patterns appear, or
+extract data from parts of certain lines while discarding the rest.  To
+write a program to do this in a language such as C or Pascal is a
+time-consuming inconvenience that may take many lines of code.  The job
+may be easier with `awk'.
+
+   The `awk' utility interprets a special-purpose programming language
+that makes it possible to handle simple data-reformatting jobs with
+just a few lines of code.
+
+   The GNU implementation of `awk' is called `gawk'; it is fully upward
+compatible with the System V Release 4 version of `awk'.  `gawk' is
+also upward compatible with the POSIX specification of the `awk'
+language.  This means that all properly written `awk' programs should
+work with `gawk'.  Thus, we usually don't distinguish between `gawk'
+and other `awk' implementations.
+
+   Using `awk' you can:
+
+   * manage small, personal databases
+
+   * generate reports
+
+   * validate data
+
+   * produce indexes, and perform other document preparation tasks
+
+   * even experiment with algorithms that can be adapted later to other
+     computer languages
+
+* Menu:
+
+* This Manual::                 Using this Info file. Includes sample
+                                input files that you can use.
+* Conventions::                 Typographical Conventions.
+* Sample Data Files::           Sample data files for use in the `awk'
+                                programs illustrated in this Info file.
+
+
+File: gawk.info,  Node: This Manual,  Next: Conventions,  Prev: What Is Awk,  Up: What Is Awk
+
+Using This Book
+===============
+
+   The term `awk' refers to a particular program, and to the language
+you use to tell this program what to do.  When we need to be careful,
+we call the program "the `awk' utility" and the language "the `awk'
+language."  The term `gawk' refers to a version of `awk' developed as
+part the GNU project.  The purpose of this Info file is to explain both
+the `awk' language and how to run the `awk' utility.
+
+   The main purpose of the Info file is to explain the features of
+`awk', as defined in the POSIX standard.  It does so in the context of
+one particular implementation, `gawk'. While doing so, it will also
+attempt to describe important differences between `gawk' and other
+`awk' implementations.  Finally, any `gawk' features that are not in
+the POSIX standard for `awk' will be noted.
+
+   The term "`awk' program" refers to a program written by you in the
+`awk' programming language.
+
+   *Note Getting Started with `awk': Getting Started, for the bare
+essentials you need to know to start using `awk'.
+
+   Some useful "one-liners" are included to give you a feel for the
+`awk' language (*note Useful One Line Programs: One-liners.).
+
+   Many sample `awk' programs have been provided for you (*note A
+Library of `awk' Functions: Library Functions.; also *note Practical
+`awk' Programs: Sample Programs.).
+
+   The entire `awk' language is summarized for quick reference in *Note
+`gawk' Summary: Gawk Summary.  Look there if you just need to refresh
+your memory about a particular feature.
+
+   If you find terms that you aren't familiar with, try looking them up
+in the glossary (*note Glossary::).
+
+   Most of the time complete `awk' programs are used as examples, but in
+some of the more advanced sections, only the part of the `awk' program
+that illustrates the concept being described is shown.
+
+   While this Info file is aimed principally at people who have not been
+exposed to `awk', there is a lot of information here that even the `awk'
+expert should find useful.  In particular, the description of POSIX
+`awk', and the example programs in *Note A Library of `awk' Functions:
+Library Functions, and *Note Practical `awk' Programs: Sample Programs,
+should be of interest.
+
+Dark Corners
+------------
+
+   Until the POSIX standard (and `The Gawk Manual'), many features of
+`awk' were either poorly documented, or not documented at all.
+Descriptions of such features (often called "dark corners") are noted
+in this Info file with "(d.c.)".  They also appear in the index under
+the heading "dark corner."
+
+
+File: gawk.info,  Node: Conventions,  Next: Sample Data Files,  Prev: This Manual,  Up: What Is Awk
+
+Typographical Conventions
+=========================
+
+   This Info file is written using Texinfo, the GNU documentation
+formatting language.  A single Texinfo source file is used to produce
+both the printed and on-line versions of the documentation.  This
+section briefly documents the typographical conventions used in Texinfo.
+
+   Examples you would type at the command line are preceded by the
+common shell primary and secondary prompts, `$' and `>'.  Output from
+the command is preceded by the glyph "-|".  This typically represents
+the command's standard output.  Error messages, and other output on the
+command's standard error, are preceded by the glyph "error-->".  For
+example:
+
+     $ echo hi on stdout
+     -| hi on stdout
+     $ echo hello on stderr 1>&2
+     error--> hello on stderr
+
+   Characters that you type at the keyboard look `like this'.  In
+particular, there are special characters called "control characters."
+These are characters that you type by holding down both the `CONTROL'
+key and another key, at the same time.  For example, a `Control-d' is
+typed by first pressing and holding the `CONTROL' key, next pressing
+the `d' key, and finally releasing both keys.
+
+
+File: gawk.info,  Node: Sample Data Files,  Prev: Conventions,  Up: What Is Awk
+
+Data Files for the Examples
+===========================
+
+   Many of the examples in this Info file take their input from two
+sample data files.  The first, called `BBS-list', represents a list of
+computer bulletin board systems together with information about those
+systems.  The second data file, called `inventory-shipped', contains
+information about shipments on a monthly basis.  In both files, each
+line is considered to be one "record".
+
+   In the file `BBS-list', each record contains the name of a computer
+bulletin board, its phone number, the board's baud rate(s), and a code
+for the number of hours it is operational.  An `A' in the last column
+means the board operates 24 hours a day.  A `B' in the last column
+means the board operates evening and weekend hours, only.  A `C' means
+the board operates only on weekends.
+
+     aardvark     555-5553     1200/300          B
+     alpo-net     555-3412     2400/1200/300     A
+     barfly       555-7685     1200/300          A
+     bites        555-1675     2400/1200/300     A
+     camelot      555-0542     300               C
+     core         555-2912     1200/300          C
+     fooey        555-1234     2400/1200/300     B
+     foot         555-6699     1200/300          B
+     macfoo       555-6480     1200/300          A
+     sdace        555-3430     2400/1200/300     A
+     sabafoo      555-2127     1200/300          C
+
+   The second data file, called `inventory-shipped', represents
+information about shipments during the year.  Each record contains the
+month of the year, the number of green crates shipped, the number of
+red boxes shipped, the number of orange bags shipped, and the number of
+blue packages shipped, respectively.  There are 16 entries, covering
+the 12 months of one year and four months of the next year.
+
+     Jan  13  25  15 115
+     Feb  15  32  24 226
+     Mar  15  24  34 228
+     Apr  31  52  63 420
+     May  16  34  29 208
+     Jun  31  42  75 492
+     Jul  24  34  67 436
+     Aug  15  34  47 316
+     Sep  13  55  37 277
+     Oct  29  54  68 525
+     Nov  20  87  82 577
+     Dec  17  35  61 401
+     
+     Jan  21  36  64 620
+     Feb  26  58  80 652
+     Mar  24  75  70 495
+     Apr  21  70  74 514
+
+   If you are reading this in GNU Emacs using Info, you can copy the
+regions of text showing these sample files into your own test files.
+This way you can try out the examples shown in the remainder of this
+document.  You do this by using the command `M-x write-region' to copy
+text from the Info file into a file for use with `awk' (*Note
+Miscellaneous File Operations: (emacs)Misc File Ops, for more
+information).  Using this information, create your own `BBS-list' and
+`inventory-shipped' files, and practice what you learn in this Info
+file.
+
+   If you are using the stand-alone version of Info, see *Note
+Extracting Programs from Texinfo Source Files: Extract Program, for an
+`awk' program that will extract these data files from `gawk.texi', the
+Texinfo source file for this Info file.
+
+
+File: gawk.info,  Node: Getting Started,  Next: One-liners,  Prev: What Is Awk,  Up: Top
+
+Getting Started with `awk'
+**************************
+
+   The basic function of `awk' is to search files for lines (or other
+units of text) that contain certain patterns.  When a line matches one
+of the patterns, `awk' performs specified actions on that line.  `awk'
+keeps processing input lines in this way until the end of the input
+files are reached.
+
+   Programs in `awk' are different from programs in most other
+languages, because `awk' programs are "data-driven"; that is, you
+describe the data you wish to work with, and then what to do when you
+find it.  Most other languages are "procedural"; you have to describe,
+in great detail, every step the program is to take.  When working with
+procedural languages, it is usually much harder to clearly describe the
+data your program will process.  For this reason, `awk' programs are
+often refreshingly easy to both write and read.
+
+   When you run `awk', you specify an `awk' "program" that tells `awk'
+what to do.  The program consists of a series of "rules".  (It may also
+contain "function definitions", an advanced feature which we will
+ignore for now.  *Note User-defined Functions: User-defined.)  Each
+rule specifies one pattern to search for, and one action to perform
+when that pattern is found.
+
+   Syntactically, a rule consists of a pattern followed by an action.
+The action is enclosed in curly braces to separate it from the pattern.
+Rules are usually separated by newlines.  Therefore, an `awk' program
+looks like this:
+
+     PATTERN { ACTION }
+     PATTERN { ACTION }
+     ...
+
+* Menu:
+
+* Names::                       What name to use to find `awk'.
+* Running gawk::                How to run `gawk' programs; includes
+                                command line syntax.
+* Very Simple::                 A very simple example.
+* Two Rules::                   A less simple one-line example with two rules.
+* More Complex::                A more complex example.
+* Statements/Lines::            Subdividing or combining statements into
+                                lines.
+* Other Features::              Other Features of `awk'.
+* When::                        When to use `gawk' and when to use other
+                                things.
+
+
+File: gawk.info,  Node: Names,  Next: Running gawk,  Prev: Getting Started,  Up: Getting Started
+
+A Rose By Any Other Name
+========================
+
+   The `awk' language has evolved over the years. Full details are
+provided in *Note The Evolution of the `awk' Language: Language History.
+The language described in this Info file is often referred to as "new
+`awk'."
+
+   Because of this, many systems have multiple versions of `awk'.  Some
+systems have an `awk' utility that implements the original version of
+the `awk' language, and a `nawk' utility for the new version.  Others
+have an `oawk' for the "old `awk'" language, and plain `awk' for the
+new one.  Still others only have one version, usually the new one.(1)
+
+   All in all, this makes it difficult for you to know which version of
+`awk' you should run when writing your programs.  The best advice we
+can give here is to check your local documentation. Look for `awk',
+`oawk', and `nawk', as well as for `gawk'. Chances are, you will have
+some version of new `awk' on your system, and that is what you should
+use when running your programs.  (Of course, if you're reading this
+Info file, chances are good that you have `gawk'!)
+
+   Throughout this Info file, whenever we refer to a language feature
+that should be available in any complete implementation of POSIX `awk',
+we simply use the term `awk'.  When referring to a feature that is
+specific to the GNU implementation, we use the term `gawk'.
+
+   ---------- Footnotes ----------
+
+   (1) Often, these systems use `gawk' for their `awk' implementation!
+
+
+File: gawk.info,  Node: Running gawk,  Next: Very Simple,  Prev: Names,  Up: Getting Started
+
+How to Run `awk' Programs
+=========================
+
+   There are several ways to run an `awk' program.  If the program is
+short, it is easiest to include it in the command that runs `awk', like
+this:
+
+     awk 'PROGRAM' INPUT-FILE1 INPUT-FILE2 ...
+
+where PROGRAM consists of a series of patterns and actions, as
+described earlier.  (The reason for the single quotes is described
+below, in *Note One-shot Throw-away `awk' Programs: One-shot.)
+
+   When the program is long, it is usually more convenient to put it in
+a file and run it with a command like this:
+
+     awk -f PROGRAM-FILE INPUT-FILE1 INPUT-FILE2 ...
+
+* Menu:
+
+* One-shot::                    Running a short throw-away `awk' program.
+* Read Terminal::               Using no input files (input from terminal
+                                instead).
+* Long::                        Putting permanent `awk' programs in
+                                files.
+* Executable Scripts::          Making self-contained `awk' programs.
+* Comments::                    Adding documentation to `gawk' programs.
+
+
+File: gawk.info,  Node: One-shot,  Next: Read Terminal,  Prev: Running gawk,  Up: Running gawk
+
+One-shot Throw-away `awk' Programs
+----------------------------------
+
+   Once you are familiar with `awk', you will often type in simple
+programs the moment you want to use them.  Then you can write the
+program as the first argument of the `awk' command, like this:
+
+     awk 'PROGRAM' INPUT-FILE1 INPUT-FILE2 ...
+
+where PROGRAM consists of a series of PATTERNS and ACTIONS, as
+described earlier.
+
+   This command format instructs the "shell", or command interpreter,
+to start `awk' and use the PROGRAM to process records in the input
+file(s).  There are single quotes around PROGRAM so that the shell
+doesn't interpret any `awk' characters as special shell characters.
+They also cause the shell to treat all of PROGRAM as a single argument
+for `awk' and allow PROGRAM to be more than one line long.
+
+   This format is also useful for running short or medium-sized `awk'
+programs from shell scripts, because it avoids the need for a separate
+file for the `awk' program.  A self-contained shell script is more
+reliable since there are no other files to misplace.
+
+   *Note Useful One Line Programs: One-liners, presents several short,
+self-contained programs.
+
+   As an interesting side point, the command
+
+     awk '/foo/' FILES ...
+
+is essentially the same as
+
+     egrep foo FILES ...
+
+
+File: gawk.info,  Node: Read Terminal,  Next: Long,  Prev: One-shot,  Up: Running gawk
+
+Running `awk' without Input Files
+---------------------------------
+
+   You can also run `awk' without any input files.  If you type the
+command line:
+
+     awk 'PROGRAM'
+
+then `awk' applies the PROGRAM to the "standard input", which usually
+means whatever you type on the terminal.  This continues until you
+indicate end-of-file by typing `Control-d'.  (On other operating
+systems, the end-of-file character may be different.  For example, on
+OS/2 and MS-DOS, it is `Control-z'.)
+
+   For example, the following program prints a friendly piece of advice
+(from Douglas Adams' `The Hitchhiker's Guide to the Galaxy'), to keep
+you from worrying about the complexities of computer programming
+(`BEGIN' is a feature we haven't discussed yet).
+
+     $ awk "BEGIN { print \"Don't Panic!\" }"
+     -| Don't Panic!
+
+   This program does not read any input.  The `\' before each of the
+inner double quotes is necessary because of the shell's quoting rules,
+in particular because it mixes both single quotes and double quotes.
+
+   This next simple `awk' program emulates the `cat' utility; it copies
+whatever you type at the keyboard to its standard output. (Why this
+works is explained shortly.)
+
+     $ awk '{ print }'
+     Now is the time for all good men
+     -| Now is the time for all good men
+     to come to the aid of their country.
+     -| to come to the aid of their country.
+     Four score and seven years ago, ...
+     -| Four score and seven years ago, ...
+     What, me worry?
+     -| What, me worry?
+     Control-d
+
+
+File: gawk.info,  Node: Long,  Next: Executable Scripts,  Prev: Read Terminal,  Up: Running gawk
+
+Running Long Programs
+---------------------
+
+   Sometimes your `awk' programs can be very long.  In this case it is
+more convenient to put the program into a separate file.  To tell `awk'
+to use that file for its program, you type:
+
+     awk -f SOURCE-FILE INPUT-FILE1 INPUT-FILE2 ...
+
+   The `-f' instructs the `awk' utility to get the `awk' program from
+the file SOURCE-FILE.  Any file name can be used for SOURCE-FILE.  For
+example, you could put the program:
+
+     BEGIN { print "Don't Panic!" }
+
+into the file `advice'.  Then this command:
+
+     awk -f advice
+
+does the same thing as this one:
+
+     awk "BEGIN { print \"Don't Panic!\" }"
+
+which was explained earlier (*note Running `awk' without Input Files:
+Read Terminal.).  Note that you don't usually need single quotes around
+the file name that you specify with `-f', because most file names don't
+contain any of the shell's special characters.  Notice that in
+`advice', the `awk' program did not have single quotes around it.  The
+quotes are only needed for programs that are provided on the `awk'
+command line.
+
+   If you want to identify your `awk' program files clearly as such,
+you can add the extension `.awk' to the file name.  This doesn't affect
+the execution of the `awk' program, but it does make "housekeeping"
+easier.
+
+
+File: gawk.info,  Node: Executable Scripts,  Next: Comments,  Prev: Long,  Up: Running gawk
+
+Executable `awk' Programs
+-------------------------
+
+   Once you have learned `awk', you may want to write self-contained
+`awk' scripts, using the `#!' script mechanism.  You can do this on
+many Unix systems(1) (and someday on the GNU system).
+
+   For example, you could update the file `advice' to look like this:
+
+     #! /bin/awk -f
+     
+     BEGIN    { print "Don't Panic!" }
+
+After making this file executable (with the `chmod' utility), you can
+simply type `advice' at the shell, and the system will arrange to run
+`awk'(2) as if you had typed `awk -f advice'.
+
+     $ advice
+     -| Don't Panic!
+
+Self-contained `awk' scripts are useful when you want to write a
+program which users can invoke without their having to know that the
+program is written in `awk'.
+
+   Some older systems do not support the `#!' mechanism. You can get a
+similar effect using a regular shell script.  It would look something
+like this:
+
+     : The colon ensures execution by the standard shell.
+     awk 'PROGRAM' "$@"
+
+   Using this technique, it is _vital_ to enclose the PROGRAM in single
+quotes to protect it from interpretation by the shell.  If you omit the
+quotes, only a shell wizard can predict the results.
+
+   The `"$@"' causes the shell to forward all the command line
+arguments to the `awk' program, without interpretation.  The first
+line, which starts with a colon, is used so that this shell script will
+work even if invoked by a user who uses the C shell.  (Not all older
+systems obey this convention, but many do.)
+
+   ---------- Footnotes ----------
+
+   (1) The `#!' mechanism works on Linux systems, Unix systems derived
+from Berkeley Unix, System V Release 4, and some System V Release 3
+systems.
+
+   (2) The line beginning with `#!' lists the full file name of an
+interpreter to be run, and an optional initial command line argument to
+pass to that interpreter.  The operating system then runs the
+interpreter with the given argument and the full argument list of the
+executed program.  The first argument in the list is the full file name
+of the `awk' program.  The rest of the argument list will either be
+options to `awk', or data files, or both.
+
+
+File: gawk.info,  Node: Comments,  Prev: Executable Scripts,  Up: Running gawk
+
+Comments in `awk' Programs
+--------------------------
+
+   A "comment" is some text that is included in a program for the sake
+of human readers; it is not really part of the program.  Comments can
+explain what the program does, and how it works.  Nearly all
+programming languages have provisions for comments, because programs are
+typically hard to understand without their extra help.
+
+   In the `awk' language, a comment starts with the sharp sign
+character, `#', and continues to the end of the line.  The `#' does not
+have to be the first character on the line. The `awk' language ignores
+the rest of a line following a sharp sign.  For example, we could have
+put the following into `advice':
+
+     # This program prints a nice friendly message.  It helps
+     # keep novice users from being afraid of the computer.
+     BEGIN    { print "Don't Panic!" }
+
+   You can put comment lines into keyboard-composed throw-away `awk'
+programs also, but this usually isn't very useful; the purpose of a
+comment is to help you or another person understand the program at a
+later time.
+
+
+File: gawk.info,  Node: Very Simple,  Next: Two Rules,  Prev: Running gawk,  Up: Getting Started
+
+A Very Simple Example
+=====================
+
+   The following command runs a simple `awk' program that searches the
+input file `BBS-list' for the string of characters: `foo'.  (A string
+of characters is usually called a "string".  The term "string" is
+perhaps based on similar usage in English, such as "a string of
+pearls," or, "a string of cars in a train.")
+
+     awk '/foo/ { print $0 }' BBS-list
+
+When lines containing `foo' are found, they are printed, because
+`print $0' means print the current line.  (Just `print' by itself means
+the same thing, so we could have written that instead.)
+
+   You will notice that slashes, `/', surround the string `foo' in the
+`awk' program.  The slashes indicate that `foo' is a pattern to search
+for.  This type of pattern is called a "regular expression", and is
+covered in more detail later (*note Regular Expressions: Regexp.).  The
+pattern is allowed to match parts of words.  There are single-quotes
+around the `awk' program so that the shell won't interpret any of it as
+special shell characters.
+
+   Here is what this program prints:
+
+     $ awk '/foo/ { print $0 }' BBS-list
+     -| fooey        555-1234     2400/1200/300     B
+     -| foot         555-6699     1200/300          B
+     -| macfoo       555-6480     1200/300          A
+     -| sabafoo      555-2127     1200/300          C
+
+   In an `awk' rule, either the pattern or the action can be omitted,
+but not both.  If the pattern is omitted, then the action is performed
+for _every_ input line.  If the action is omitted, the default action
+is to print all lines that match the pattern.
+
+   Thus, we could leave out the action (the `print' statement and the
+curly braces) in the above example, and the result would be the same:
+all lines matching the pattern `foo' would be printed.  By comparison,
+omitting the `print' statement but retaining the curly braces makes an
+empty action that does nothing; then no lines would be printed.
+
+
+File: gawk.info,  Node: Two Rules,  Next: More Complex,  Prev: Very Simple,  Up: Getting Started
+
+An Example with Two Rules
+=========================
+
+   The `awk' utility reads the input files one line at a time.  For
+each line, `awk' tries the patterns of each of the rules.  If several
+patterns match then several actions are run, in the order in which they
+appear in the `awk' program.  If no patterns match, then no actions are
+run.
+
+   After processing all the rules (perhaps none) that match the line,
+`awk' reads the next line (however, *note The `next' Statement: Next
+Statement., and also *note The `nextfile' Statement: Nextfile
+Statement.).  This continues until the end of the file is reached.
+
+   For example, the `awk' program:
+
+     /12/  { print $0 }
+     /21/  { print $0 }
+
+contains two rules.  The first rule has the string `12' as the pattern
+and `print $0' as the action.  The second rule has the string `21' as
+the pattern and also has `print $0' as the action.  Each rule's action
+is enclosed in its own pair of braces.
+
+   This `awk' program prints every line that contains the string `12'
+_or_ the string `21'.  If a line contains both strings, it is printed
+twice, once by each rule.
+
+   This is what happens if we run this program on our two sample data
+files, `BBS-list' and `inventory-shipped', as shown here:
+
+     $ awk '/12/ { print $0 }
+     >      /21/ { print $0 }' BBS-list inventory-shipped
+     -| aardvark     555-5553     1200/300          B
+     -| alpo-net     555-3412     2400/1200/300     A
+     -| barfly       555-7685     1200/300          A
+     -| bites        555-1675     2400/1200/300     A
+     -| core         555-2912     1200/300          C
+     -| fooey        555-1234     2400/1200/300     B
+     -| foot         555-6699     1200/300          B
+     -| macfoo       555-6480     1200/300          A
+     -| sdace        555-3430     2400/1200/300     A
+     -| sabafoo      555-2127     1200/300          C
+     -| sabafoo      555-2127     1200/300          C
+     -| Jan  21  36  64 620
+     -| Apr  21  70  74 514
+
+Note how the line in `BBS-list' beginning with `sabafoo' was printed
+twice, once for each rule.
+
+
+File: gawk.info,  Node: More Complex,  Next: Statements/Lines,  Prev: Two Rules,  Up: Getting Started
+
+A More Complex Example
+======================
+
+   Here is an example to give you an idea of what typical `awk'
+programs do.  This example shows how `awk' can be used to summarize,
+select, and rearrange the output of another utility.  It uses features
+that haven't been covered yet, so don't worry if you don't understand
+all the details.
+
+     ls -lg | awk '$6 == "Nov" { sum += $5 }
+                  END { print sum }'
+
+   This command prints the total number of bytes in all the files in the
+current directory that were last modified in November (of any year).
+(In the C shell you would need to type a semicolon and then a backslash
+at the end of the first line; in a POSIX-compliant shell, such as the
+Bourne shell or Bash, the GNU Bourne-Again shell, you can type the
+example as shown.)
+
+   The `ls -lg' part of this example is a system command that gives you
+a listing of the files in a directory, including file size and the date
+the file was last modified. Its output looks like this:
+
+     -rw-r--r--  1 arnold   user   1933 Nov  7 13:05 Makefile
+     -rw-r--r--  1 arnold   user  10809 Nov  7 13:03 gawk.h
+     -rw-r--r--  1 arnold   user    983 Apr 13 12:14 gawk.tab.h
+     -rw-r--r--  1 arnold   user  31869 Jun 15 12:20 gawk.y
+     -rw-r--r--  1 arnold   user  22414 Nov  7 13:03 gawk1.c
+     -rw-r--r--  1 arnold   user  37455 Nov  7 13:03 gawk2.c
+     -rw-r--r--  1 arnold   user  27511 Dec  9 13:07 gawk3.c
+     -rw-r--r--  1 arnold   user   7989 Nov  7 13:03 gawk4.c
+
+The first field contains read-write permissions, the second field
+contains the number of links to the file, and the third field
+identifies the owner of the file. The fourth field identifies the group
+of the file.  The fifth field contains the size of the file in bytes.
+The sixth, seventh and eighth fields contain the month, day, and time,
+respectively, that the file was last modified.  Finally, the ninth field
+contains the name of the file.
+
+   The `$6 == "Nov"' in our `awk' program is an expression that tests
+whether the sixth field of the output from `ls -lg' matches the string
+`Nov'.  Each time a line has the string `Nov' for its sixth field, the
+action `sum += $5' is performed.  This adds the fifth field (the file
+size) to the variable `sum'.  As a result, when `awk' has finished
+reading all the input lines, `sum' is the sum of the sizes of files
+whose lines matched the pattern.  (This works because `awk' variables
+are automatically initialized to zero.)
+
+   After the last line of output from `ls' has been processed, the
+`END' rule is executed, and the value of `sum' is printed.  In this
+example, the value of `sum' would be 80600.
+
+   These more advanced `awk' techniques are covered in later sections
+(*note Overview of Actions: Action Overview.).  Before you can move on
+to more advanced `awk' programming, you have to know how `awk'
+interprets your input and displays your output.  By manipulating fields
+and using `print' statements, you can produce some very useful and
+impressive looking reports.
+
+
+File: gawk.info,  Node: Statements/Lines,  Next: Other Features,  Prev: More Complex,  Up: Getting Started
+
+`awk' Statements Versus Lines
+=============================
+
+   Most often, each line in an `awk' program is a separate statement or
+separate rule, like this:
+
+     awk '/12/  { print $0 }
+          /21/  { print $0 }' BBS-list inventory-shipped
+
+   However, `gawk' will ignore newlines after any of the following:
+
+     ,    {    ?    :    ||    &&    do    else
+
+A newline at any other point is considered the end of the statement.
+(Splitting lines after `?' and `:' is a minor `gawk' extension.  The
+`?' and `:' referred to here is the three operand conditional
+expression described in *Note Conditional Expressions: Conditional Exp.)
+
+   If you would like to split a single statement into two lines at a
+point where a newline would terminate it, you can "continue" it by
+ending the first line with a backslash character, `\'.  The backslash
+must be the final character on the line to be recognized as a
+continuation character.  This is allowed absolutely anywhere in the
+statement, even in the middle of a string or regular expression.  For
+example:
+
+     awk '/This regular expression is too long, so continue it\
+      on the next line/ { print $1 }'
+
+We have generally not used backslash continuation in the sample programs
+in this Info file.  Since in `gawk' there is no limit on the length of
+a line, it is never strictly necessary; it just makes programs more
+readable.  For this same reason, as well as for clarity, we have kept
+most statements short in the sample programs presented throughout the
+Info file.  Backslash continuation is most useful when your `awk'
+program is in a separate source file, instead of typed in on the
+command line.  You should also note that many `awk' implementations are
+more particular about where you may use backslash continuation. For
+example, they may not allow you to split a string constant using
+backslash continuation.  Thus, for maximal portability of your `awk'
+programs, it is best not to split your lines in the middle of a regular
+expression or a string.
+
+   *Caution: backslash continuation does not work as described above
+with the C shell.*  Continuation with backslash works for `awk'
+programs in files, and also for one-shot programs _provided_ you are
+using a POSIX-compliant shell, such as the Bourne shell or Bash, the
+GNU Bourne-Again shell.  But the C shell (`csh') behaves differently!
+There, you must use two backslashes in a row, followed by a newline.
+Note also that when using the C shell, _every_ newline in your awk
+program must be escaped with a backslash. To illustrate:
+
+     % awk 'BEGIN { \
+     ?   print \\
+     ?       "hello, world" \
+     ? }'
+     -| hello, world
+
+Here, the `%' and `?' are the C shell's primary and secondary prompts,
+analogous to the standard shell's `$' and `>'.
+
+   `awk' is a line-oriented language.  Each rule's action has to begin
+on the same line as the pattern.  To have the pattern and action on
+separate lines, you _must_ use backslash continuation--there is no
+other way.
+
+   Note that backslash continuation and comments do not mix. As soon as
+`awk' sees the `#' that starts a comment, it ignores _everything_ on
+the rest of the line. For example:
+
+     $ gawk 'BEGIN { print "dont panic" # a friendly \
+     >                                    BEGIN rule
+     > }'
+     error--> gawk: cmd. line:2:                BEGIN rule
+     error--> gawk: cmd. line:2:                ^ parse error
+
+Here, it looks like the backslash would continue the comment onto the
+next line. However, the backslash-newline combination is never even
+noticed, since it is "hidden" inside the comment. Thus, the `BEGIN' is
+noted as a syntax error.
+
+   When `awk' statements within one rule are short, you might want to
+put more than one of them on a line.  You do this by separating the
+statements with a semicolon, `;'.
+
+   This also applies to the rules themselves.  Thus, the previous
+program could have been written:
+
+     /12/ { print $0 } ; /21/ { print $0 }
+
+*Note:* the requirement that rules on the same line must be separated
+with a semicolon was not in the original `awk' language; it was added
+for consistency with the treatment of statements within an action.
+
+
+File: gawk.info,  Node: Other Features,  Next: When,  Prev: Statements/Lines,  Up: Getting Started
+
+Other Features of `awk'
+=======================
+
+   The `awk' language provides a number of predefined, or built-in
+variables, which your programs can use to get information from `awk'.
+There are other variables your program can set to control how `awk'
+processes your data.
+
+   In addition, `awk' provides a number of built-in functions for doing
+common computational and string related operations.
+
+   As we develop our presentation of the `awk' language, we introduce
+most of the variables and many of the functions. They are defined
+systematically in *Note Built-in Variables::, and *Note Built-in
+Functions: Built-in.
+
+
+File: gawk.info,  Node: When,  Prev: Other Features,  Up: Getting Started
+
+When to Use `awk'
+=================
+
+   You might wonder how `awk' might be useful for you.  Using utility
+programs, advanced patterns, field separators, arithmetic statements,
+and other selection criteria, you can produce much more complex output.
+The `awk' language is very useful for producing reports from large
+amounts of raw data, such as summarizing information from the output of
+other utility programs like `ls'.  (*Note A More Complex Example: More
+Complex.)
+
+   Programs written with `awk' are usually much smaller than they would
+be in other languages.  This makes `awk' programs easy to compose and
+use.  Often, `awk' programs can be quickly composed at your terminal,
+used once, and thrown away.  Since `awk' programs are interpreted, you
+can avoid the (usually lengthy) compilation part of the typical
+edit-compile-test-debug cycle of software development.
+
+   Complex programs have been written in `awk', including a complete
+retargetable assembler for eight-bit microprocessors (*note Glossary::,
+for more information) and a microcode assembler for a special purpose
+Prolog computer.  However, `awk''s capabilities are strained by tasks of
+such complexity.
+
+   If you find yourself writing `awk' scripts of more than, say, a few
+hundred lines, you might consider using a different programming
+language.  Emacs Lisp is a good choice if you need sophisticated string
+or pattern matching capabilities.  The shell is also good at string and
+pattern matching; in addition, it allows powerful use of the system
+utilities.  More conventional languages, such as C, C++, and Lisp, offer
+better facilities for system programming and for managing the complexity
+of large programs.  Programs in these languages may require more lines
+of source code than the equivalent `awk' programs, but they are easier
+to maintain and usually run more efficiently.
+
+
+File: gawk.info,  Node: One-liners,  Next: Regexp,  Prev: Getting Started,  Up: Top
+
+Useful One Line Programs
+************************
+
+   Many useful `awk' programs are short, just a line or two.  Here is a
+collection of useful, short programs to get you started.  Some of these
+programs contain constructs that haven't been covered yet.  The
+description of the program will give you a good idea of what is going
+on, but please read the rest of the Info file to become an `awk' expert!
+
+   Most of the examples use a data file named `data'.  This is just a
+placeholder; if you were to use these programs yourself, you would
+substitute your own file names for `data'.
+
+   Since you are reading this in Info, each line of the example code is
+enclosed in quotes, to represent text that you would type literally.
+The examples themselves represent shell commands that use single quotes
+to keep the shell from interpreting the contents of the program.  When
+reading the examples, focus on the text between the open and close
+quotes.
+
+`awk '{ if (length($0) > max) max = length($0) }'
+`     END { print max }' data'
+     This program prints the length of the longest input line.
+
+`awk 'length($0) > 80' data'
+     This program prints every line that is longer than 80 characters.
+     The sole rule has a relational expression as its pattern, and has
+     no action (so the default action, printing the record, is used).
+
+`expand data | awk '{ if (x < length()) x = length() }'
+`                   END { print "maximum line length is " x }''
+     This program prints the length of the longest line in `data'.  The
+     input is processed by the `expand' program to change tabs into
+     spaces, so the widths compared are actually the right-margin
+     columns.
+
+`awk 'NF > 0' data'
+     This program prints every line that has at least one field.  This
+     is an easy way to delete blank lines from a file (or rather, to
+     create a new file similar to the old file but from which the blank
+     lines have been deleted).
+
+`awk 'BEGIN { for (i = 1; i <= 7; i++)'
+`               print int(101 * rand()) }''
+     This program prints seven random numbers from zero to 100,
+     inclusive.
+
+`ls -lg FILES | awk '{ x += $5 } ; END { print "total bytes: " x }''
+     This program prints the total number of bytes used by FILES.
+
+`ls -lg FILES | awk '{ x += $5 }'
+`                 END { print "total K-bytes: " (x + 1023)/1024 }''
+     This program prints the total number of kilobytes used by FILES.
+
+`awk -F: '{ print $1 }' /etc/passwd | sort'
+     This program prints a sorted list of the login names of all users.
+
+`awk 'END { print NR }' data'
+     This program counts lines in a file.
+
+`awk 'NR % 2 == 0' data'
+     This program prints the even numbered lines in the data file.  If
+     you were to use the expression `NR % 2 == 1' instead, it would
+     print the odd numbered lines.
+
+
+File: gawk.info,  Node: Regexp,  Next: Reading Files,  Prev: One-liners,  Up: Top
+
+Regular Expressions
+*******************
+
+   A "regular expression", or "regexp", is a way of describing a set of
+strings.  Because regular expressions are such a fundamental part of
+`awk' programming, their format and use deserve a separate chapter.
+
+   A regular expression enclosed in slashes (`/') is an `awk' pattern
+that matches every input record whose text belongs to that set.
+
+   The simplest regular expression is a sequence of letters, numbers, or
+both.  Such a regexp matches any string that contains that sequence.
+Thus, the regexp `foo' matches any string containing `foo'.  Therefore,
+the pattern `/foo/' matches any input record containing the three
+characters `foo', _anywhere_ in the record.  Other kinds of regexps let
+you specify more complicated classes of strings.
+
+* Menu:
+
+* Regexp Usage::                How to Use Regular Expressions.
+* Escape Sequences::            How to write non-printing characters.
+* Regexp Operators::            Regular Expression Operators.
+* GNU Regexp Operators::        Operators specific to GNU software.
+* Case-sensitivity::            How to do case-insensitive matching.
+* Leftmost Longest::            How much text matches.
+* Computed Regexps::            Using Dynamic Regexps.
+
+
+File: gawk.info,  Node: Regexp Usage,  Next: Escape Sequences,  Prev: Regexp,  Up: Regexp
+
+How to Use Regular Expressions
+==============================
+
+   A regular expression can be used as a pattern by enclosing it in
+slashes.  Then the regular expression is tested against the entire text
+of each record.  (Normally, it only needs to match some part of the
+text in order to succeed.)  For example, this prints the second field
+of each record that contains the three characters `foo' anywhere in it:
+
+     $ awk '/foo/ { print $2 }' BBS-list
+     -| 555-1234
+     -| 555-6699
+     -| 555-6480
+     -| 555-2127
+
+   Regular expressions can also be used in matching expressions.  These
+expressions allow you to specify the string to match against; it need
+not be the entire current input record.  The two operators, `~' and
+`!~', perform regular expression comparisons.  Expressions using these
+operators can be used as patterns or in `if', `while', `for', and `do'
+statements.  (*Note Control Statements in Actions: Statements.)
+
+`EXP ~ /REGEXP/'
+     This is true if the expression EXP (taken as a string) is matched
+     by REGEXP.  The following example matches, or selects, all input
+     records with the upper-case letter `J' somewhere in the first
+     field:
+
+          $ awk '$1 ~ /J/' inventory-shipped
+          -| Jan  13  25  15 115
+          -| Jun  31  42  75 492
+          -| Jul  24  34  67 436
+          -| Jan  21  36  64 620
+
+     So does this:
+
+          awk '{ if ($1 ~ /J/) print }' inventory-shipped
+
+`EXP !~ /REGEXP/'
+     This is true if the expression EXP (taken as a character string)
+     is _not_ matched by REGEXP.  The following example matches, or
+     selects, all input records whose first field _does not_ contain
+     the upper-case letter `J':
+
+          $ awk '$1 !~ /J/' inventory-shipped
+          -| Feb  15  32  24 226
+          -| Mar  15  24  34 228
+          -| Apr  31  52  63 420
+          -| May  16  34  29 208
+          ...
+
+   When a regexp is written enclosed in slashes, like `/foo/', we call
+it a "regexp constant", much like `5.27' is a numeric constant, and
+`"foo"' is a string constant.
+
+
+File: gawk.info,  Node: Escape Sequences,  Next: Regexp Operators,  Prev: Regexp Usage,  Up: Regexp
+
+Escape Sequences
+================
+
+   Some characters cannot be included literally in string constants
+(`"foo"') or regexp constants (`/foo/').  You represent them instead
+with "escape sequences", which are character sequences beginning with a
+backslash (`\').
+
+   One use of an escape sequence is to include a double-quote character
+in a string constant.  Since a plain double-quote would end the string,
+you must use `\"' to represent an actual double-quote character as a
+part of the string.  For example:
+
+     $ awk 'BEGIN { print "He said \"hi!\" to her." }'
+     -| He said "hi!" to her.
+
+   The  backslash character itself is another character that cannot be
+included normally; you write `\\' to put one backslash in the string or
+regexp.  Thus, the string whose contents are the two characters `"' and
+`\' must be written `"\"\\"'.
+
+   Another use of backslash is to represent unprintable characters such
+as tab or newline.  While there is nothing to stop you from entering
+most unprintable characters directly in a string constant or regexp
+constant, they may look ugly.
+
+   Here is a table of all the escape sequences used in `awk', and what
+they represent. Unless noted otherwise, all of these escape sequences
+apply to both string constants and regexp constants.
+
+`\\'
+     A literal backslash, `\'.
+
+`\a'
+     The "alert" character, `Control-g', ASCII code 7 (BEL).
+
+`\b'
+     Backspace, `Control-h', ASCII code 8 (BS).
+
+`\f'
+     Formfeed, `Control-l', ASCII code 12 (FF).
+
+`\n'
+     Newline, `Control-j', ASCII code 10 (LF).
+
+`\r'
+     Carriage return, `Control-m', ASCII code 13 (CR).
+
+`\t'
+     Horizontal tab, `Control-i', ASCII code 9 (HT).
+
+`\v'
+     Vertical tab, `Control-k', ASCII code 11 (VT).
+
+`\NNN'
+     The octal value NNN, where NNN are one to three digits between `0'
+     and `7'.  For example, the code for the ASCII ESC (escape)
+     character is `\033'.
+
+`\xHH...'
+     The hexadecimal value HH, where HH are hexadecimal digits (`0'
+     through `9' and either `A' through `F' or `a' through `f').  Like
+     the same construct in ANSI C, the escape sequence continues until
+     the first non-hexadecimal digit is seen.  However, using more than
+     two hexadecimal digits produces undefined results. (The `\x'
+     escape sequence is not allowed in POSIX `awk'.)
+
+`\/'
+     A literal slash (necessary for regexp constants only).  You use
+     this when you wish to write a regexp constant that contains a
+     slash. Since the regexp is delimited by slashes, you need to
+     escape the slash that is part of the pattern, in order to tell
+     `awk' to keep processing the rest of the regexp.
+
+`\"'
+     A literal double-quote (necessary for string constants only).  You
+     use this when you wish to write a string constant that contains a
+     double-quote. Since the string is delimited by double-quotes, you
+     need to escape the quote that is part of the string, in order to
+     tell `awk' to keep processing the rest of the string.
+
+   In `gawk', there are additional two character sequences that begin
+with backslash that have special meaning in regexps.  *Note Additional
+Regexp Operators Only in `gawk': GNU Regexp Operators.
+
+   In a string constant, what happens if you place a backslash before
+something that is not one of the characters listed above?  POSIX `awk'
+purposely leaves this case undefined.  There are two choices.
+
+   * Strip the backslash out.  This is what Unix `awk' and `gawk' both
+     do.  For example, `"a\qc"' is the same as `"aqc"'.
+
+   * Leave the backslash alone.  Some other `awk' implementations do
+     this.  In such implementations, `"a\qc"' is the same as if you had
+     typed `"a\\qc"'.
+
+   In a regexp, a backslash before any character that is not in the
+above table, and not listed in *Note Additional Regexp Operators Only
+in `gawk': GNU Regexp Operators, means that the next character should
+be taken literally, even if it would normally be a regexp operator.
+E.g., `/a\+b/' matches the three characters `a+b'.
+
+   For complete portability, do not use a backslash before any
+character not listed in the table above.
+
+   Another interesting question arises. Suppose you use an octal or
+hexadecimal escape to represent a regexp metacharacter (*note Regular
+Expression Operators: Regexp Operators.).  Does `awk' treat the
+character as literal character, or as a regexp operator?
+
+   It turns out that historically, such characters were taken literally
+(d.c.).  However, the POSIX standard indicates that they should be
+treated as real metacharacters, and this is what `gawk' does.  However,
+in compatibility mode (*note Command Line Options: Options.), `gawk'
+treats the characters represented by octal and hexadecimal escape
+sequences literally when used in regexp constants. Thus, `/a\52b/' is
+equivalent to `/a\*b/'.
+
+   To summarize:
+
+  1. The escape sequences in the table above are always processed first,
+     for both string constants and regexp constants. This happens very
+     early, as soon as `awk' reads your program.
+
+  2. `gawk' processes both regexp constants and dynamic regexps (*note
+     Using Dynamic Regexps: Computed Regexps.), for the special
+     operators listed in *Note Additional Regexp Operators Only in
+     `gawk': GNU Regexp Operators.
+
+  3. A backslash before any other character means to treat that
+     character literally.
+
+
+File: gawk.info,  Node: Regexp Operators,  Next: GNU Regexp Operators,  Prev: Escape Sequences,  Up: Regexp
+
+Regular Expression Operators
+============================
+
+   You can combine regular expressions with the following characters,
+called "regular expression operators", or "metacharacters", to increase
+the power and versatility of regular expressions.
+
+   The escape sequences described in *Note Escape Sequences::, are
+valid inside a regexp.  They are introduced by a `\'.  They are
+recognized and converted into the corresponding real characters as the
+very first step in processing regexps.
+
+   Here is a table of metacharacters.  All characters that are not
+escape sequences and that are not listed in the table stand for
+themselves.
+
+`\'
+     This is used to suppress the special meaning of a character when
+     matching.  For example:
+
+          \$
+
+     matches the character `$'.
+
+`^'
+     This matches the beginning of a string.  For example:
+
+          ^@chapter
+
+     matches the `@chapter' at the beginning of a string, and can be
+     used to identify chapter beginnings in Texinfo source files.  The
+     `^' is known as an "anchor", since it anchors the pattern to
+     matching only at the beginning of the string.
+
+     It is important to realize that `^' does not match the beginning of
+     a line embedded in a string.  In this example the condition is not
+     true:
+
+          if ("line1\nLINE 2" ~ /^L/) ...
+
+`$'
+     This is similar to `^', but it matches only at the end of a string.
+     For example:
+
+          p$
+
+     matches a record that ends with a `p'.  The `$' is also an anchor,
+     and also does not match the end of a line embedded in a string.
+     In this example the condition is not true:
+
+          if ("line1\nLINE 2" ~ /1$/) ...
+
+`.'
+     The period, or dot, matches any single character, _including_ the
+     newline character.  For example:
+
+          .P
+
+     matches any single character followed by a `P' in a string.  Using
+     concatenation we can make a regular expression like `U.A', which
+     matches any three-character sequence that begins with `U' and ends
+     with `A'.
+
+     In strict POSIX mode (*note Command Line Options: Options.), `.'
+     does not match the NUL character, which is a character with all
+     bits equal to zero.  Otherwise, NUL is just another character.
+     Other versions of `awk' may not be able to match the NUL character.
+
+`[...]'
+     This is called a "character list".  It matches any _one_ of the
+     characters that are enclosed in the square brackets.  For example:
+
+          [MVX]
+
+     matches any one of the characters `M', `V', or `X' in a string.
+
+     Ranges of characters are indicated by using a hyphen between the
+     beginning and ending characters, and enclosing the whole thing in
+     brackets.  For example:
+
+          [0-9]
+
+     matches any digit.  Multiple ranges are allowed. E.g., the list
+     `[A-Za-z0-9]' is a common way to express the idea of "all
+     alphanumeric characters."
+
+     To include one of the characters `\', `]', `-' or `^' in a
+     character list, put a `\' in front of it.  For example:
+
+          [d\]]
+
+     matches either `d', or `]'.
+
+     This treatment of `\' in character lists is compatible with other
+     `awk' implementations, and is also mandated by POSIX.  The regular
+     expressions in `awk' are a superset of the POSIX specification for
+     Extended Regular Expressions (EREs).  POSIX EREs are based on the
+     regular expressions accepted by the traditional `egrep' utility.
+
+     "Character classes" are a new feature introduced in the POSIX
+     standard.  A character class is a special notation for describing
+     lists of characters that have a specific attribute, but where the
+     actual characters themselves can vary from country to country
+     and/or from character set to character set.  For example, the
+     notion of what is an alphabetic character differs in the USA and
+     in France.
+
+     A character class is only valid in a regexp _inside_ the brackets
+     of a character list.  Character classes consist of `[:', a keyword
+     denoting the class, and `:]'.  Here are the character classes
+     defined by the POSIX standard.
+
+    `[:alnum:]'
+          Alphanumeric characters.
+
+    `[:alpha:]'
+          Alphabetic characters.
+
+    `[:blank:]'
+          Space and tab characters.
+
+    `[:cntrl:]'
+          Control characters.
+
+    `[:digit:]'
+          Numeric characters.
+
+    `[:graph:]'
+          Characters that are printable and are also visible.  (A space
+          is printable, but not visible, while an `a' is both.)
+
+    `[:lower:]'
+          Lower-case alphabetic characters.
+
+    `[:print:]'
+          Printable characters (characters that are not control
+          characters.)
+
+    `[:punct:]'
+          Punctuation characters (characters that are not letter,
+          digits, control characters, or space characters).
+
+    `[:space:]'
+          Space characters (such as space, tab, and formfeed, to name a
+          few).
+
+    `[:upper:]'
+          Upper-case alphabetic characters.
+
+    `[:xdigit:]'
+          Characters that are hexadecimal digits.
+
+     For example, before the POSIX standard, to match alphanumeric
+     characters, you had to write `/[A-Za-z0-9]/'.  If your character
+     set had other alphabetic characters in it, this would not match
+     them.  With the POSIX character classes, you can write
+     `/[[:alnum:]]/', and this will match _all_ the alphabetic and
+     numeric characters in your character set.
+
+     Two additional special sequences can appear in character lists.
+     These apply to non-ASCII character sets, which can have single
+     symbols (called "collating elements") that are represented with
+     more than one character, as well as several characters that are
+     equivalent for "collating", or sorting, purposes.  (E.g., in
+     French, a plain "e" and a grave-accented "e`" are equivalent.)
+
+    Collating Symbols
+          A "collating symbol" is a multi-character collating element
+          enclosed in `[.' and `.]'.  For example, if `ch' is a
+          collating element, then `[[.ch.]]' is a regexp that matches
+          this collating element, while `[ch]' is a regexp that matches
+          either `c' or `h'.
+
+    Equivalence Classes
+          An "equivalence class" is a locale-specific name for a list of
+          characters that are equivalent. The name is enclosed in `[='
+          and `=]'.  For example, the name `e' might be used to
+          represent all of "e," "e`," and "e'." In this case, `[[=e]]'
+          is a regexp that matches any of `e', `e'',  or `e`'.
+
+     These features are very valuable in non-English speaking locales.
+
+     *Caution:* The library functions that `gawk' uses for regular
+     expression matching currently only recognize POSIX character
+     classes; they do not recognize collating symbols or equivalence
+     classes.
+
+`[^ ...]'
+     This is a "complemented character list".  The first character after
+     the `[' _must_ be a `^'.  It matches any characters _except_ those
+     in the square brackets.  For example:
+
+          [^0-9]
+
+     matches any character that is not a digit.
+
+`|'
+     This is the "alternation operator", and it is used to specify
+     alternatives.  For example:
+
+          ^P|[0-9]
+
+     matches any string that matches either `^P' or `[0-9]'.  This
+     means it matches any string that starts with `P' or contains a
+     digit.
+
+     The alternation applies to the largest possible regexps on either
+     side.  In other words, `|' has the lowest precedence of all the
+     regular expression operators.
+
+`(...)'
+     Parentheses are used for grouping in regular expressions as in
+     arithmetic.  They can be used to concatenate regular expressions
+     containing the alternation operator, `|'.  For example,
+     `@(samp|code)\{[^}]+\}' matches both `@code{foo}' and
+     `@samp{bar}'. (These are Texinfo formatting control sequences.)
+
+`*'
+     This symbol means that the preceding regular expression is to be
+     repeated as many times as necessary to find a match.  For example:
+
+          ph*
+
+     applies the `*' symbol to the preceding `h' and looks for matches
+     of one `p' followed by any number of `h's.  This will also match
+     just `p' if no `h's are present.
+
+     The `*' repeats the _smallest_ possible preceding expression.
+     (Use parentheses if you wish to repeat a larger expression.)  It
+     finds as many repetitions as possible.  For example:
+
+          awk '/\(c[ad][ad]*r x\)/ { print }' sample
+
+     prints every record in `sample' containing a string of the form
+     `(car x)', `(cdr x)', `(cadr x)', and so on.  Notice the escaping
+     of the parentheses by preceding them with backslashes.
+
+`+'
+     This symbol is similar to `*', but the preceding expression must be
+     matched at least once.  This means that:
+
+          wh+y
+
+     would match `why' and `whhy' but not `wy', whereas `wh*y' would
+     match all three of these strings.  This is a simpler way of
+     writing the last `*' example:
+
+          awk '/\(c[ad]+r x\)/ { print }' sample
+
+`?'
+     This symbol is similar to `*', but the preceding expression can be
+     matched either once or not at all.  For example:
+
+          fe?d
+
+     will match `fed' and `fd', but nothing else.
+
+`{N}'
+`{N,}'
+`{N,M}'
+     One or two numbers inside braces denote an "interval expression".
+     If there is one number in the braces, the preceding regexp is
+     repeated N times.  If there are two numbers separated by a comma,
+     the preceding regexp is repeated N to M times.  If there is one
+     number followed by a comma, then the preceding regexp is repeated
+     at least N times.
+
+    `wh{3}y'
+          matches `whhhy' but not `why' or `whhhhy'.
+
+    `wh{3,5}y'
+          matches `whhhy' or `whhhhy' or `whhhhhy', only.
+
+    `wh{2,}y'
+          matches `whhy' or `whhhy', and so on.
+
+     Interval expressions were not traditionally available in `awk'.
+     As part of the POSIX standard they were added, to make `awk' and
+     `egrep' consistent with each other.
+
+     However, since old programs may use `{' and `}' in regexp
+     constants, by default `gawk' does _not_ match interval expressions
+     in regexps.  If either `--posix' or `--re-interval' are specified
+     (*note Command Line Options: Options.), then interval expressions
+     are allowed in regexps.
+
+   In regular expressions, the `*', `+', and `?' operators, as well as
+the braces `{' and `}', have the highest precedence, followed by
+concatenation, and finally by `|'.  As in arithmetic, parentheses can
+change how operators are grouped.
+
+   If `gawk' is in compatibility mode (*note Command Line Options:
+Options.), character classes and interval expressions are not available
+in regular expressions.
+
+   The next node discusses the GNU-specific regexp operators, and
+provides more detail concerning how command line options affect the way
+`gawk' interprets the characters in regular expressions.
+
+
+File: gawk.info,  Node: GNU Regexp Operators,  Next: Case-sensitivity,  Prev: Regexp Operators,  Up: Regexp
+
+Additional Regexp Operators Only in `gawk'
+==========================================
+
+   GNU software that deals with regular expressions provides a number of
+additional regexp operators.  These operators are described in this
+section, and are specific to `gawk'; they are not available in other
+`awk' implementations.
+
+   Most of the additional operators are for dealing with word matching.
+For our purposes, a "word" is a sequence of one or more letters, digits,
+or underscores (`_').
+
+`\w'
+     This operator matches any word-constituent character, i.e. any
+     letter, digit, or underscore. Think of it as a short-hand for
+     `[[:alnum:]_]'.
+
+`\W'
+     This operator matches any character that is not word-constituent.
+     Think of it as a short-hand for `[^[:alnum:]_]'.
+
+`\<'
+     This operator matches the empty string at the beginning of a word.
+     For example, `/\<away/' matches `away', but not `stowaway'.
+
+`\>'
+     This operator matches the empty string at the end of a word.  For
+     example, `/stow\>/' matches `stow', but not `stowaway'.
+
+`\y'
+     This operator matches the empty string at either the beginning or
+     the end of a word (the word boundar*y*).  For example, `\yballs?\y'
+     matches either `ball' or `balls' as a separate word.
+
+`\B'
+     This operator matches the empty string within a word. In other
+     words, `\B' matches the empty string that occurs between two
+     word-constituent characters. For example, `/\Brat\B/' matches
+     `crate', but it does not match `dirty rat'.  `\B' is essentially
+     the opposite of `\y'.
+
+   There are two other operators that work on buffers.  In Emacs, a
+"buffer" is, naturally, an Emacs buffer.  For other programs, the
+regexp library routines that `gawk' uses consider the entire string to
+be matched as the buffer.
+
+   For `awk', since `^' and `$' always work in terms of the beginning
+and end of strings, these operators don't add any new capabilities.
+They are provided for compatibility with other GNU software.
+
+`\`'
+     This operator matches the empty string at the beginning of the
+     buffer.
+
+`\''
+     This operator matches the empty string at the end of the buffer.
+
+   In other GNU software, the word boundary operator is `\b'. However,
+that conflicts with the `awk' language's definition of `\b' as
+backspace, so `gawk' uses a different letter.
+
+   An alternative method would have been to require two backslashes in
+the GNU operators, but this was deemed to be too confusing, and the
+current method of using `\y' for the GNU `\b' appears to be the lesser
+of two evils.
+
+   The various command line options (*note Command Line Options:
+Options.)  control how `gawk' interprets characters in regexps.
+
+No options
+     In the default case, `gawk' provide all the facilities of POSIX
+     regexps and the GNU regexp operators described in *Note Regular
+     Expression Operators: Regexp Operators.  However, interval
+     expressions are not supported.
+
+`--posix'
+     Only POSIX regexps are supported, the GNU operators are not special
+     (e.g., `\w' matches a literal `w').  Interval expressions are
+     allowed.
+
+`--traditional'
+     Traditional Unix `awk' regexps are matched. The GNU operators are
+     not special, interval expressions are not available, and neither
+     are the POSIX character classes (`[[:alnum:]]' and so on).
+     Characters described by octal and hexadecimal escape sequences are
+     treated literally, even if they represent regexp metacharacters.
+
+`--re-interval'
+     Allow interval expressions in regexps, even if `--traditional' has
+     been provided.
+
+
+File: gawk.info,  Node: Case-sensitivity,  Next: Leftmost Longest,  Prev: GNU Regexp Operators,  Up: Regexp
+
+Case-sensitivity in Matching
+============================
+
+   Case is normally significant in regular expressions, both when
+matching ordinary characters (i.e. not metacharacters), and inside
+character sets.  Thus a `w' in a regular expression matches only a
+lower-case `w' and not an upper-case `W'.
+
+   The simplest way to do a case-independent match is to use a character
+list: `[Ww]'.  However, this can be cumbersome if you need to use it
+often; and it can make the regular expressions harder to read.  There
+are two alternatives that you might prefer.
+
+   One way to do a case-insensitive match at a particular point in the
+program is to convert the data to a single case, using the `tolower' or
+`toupper' built-in string functions (which we haven't discussed yet;
+*note Built-in Functions for String Manipulation: String Functions.).
+For example:
+
+     tolower($1) ~ /foo/  { ... }
+
+converts the first field to lower-case before matching against it.
+This will work in any POSIX-compliant implementation of `awk'.
+
+   Another method, specific to `gawk', is to set the variable
+`IGNORECASE' to a non-zero value (*note Built-in Variables::).  When
+`IGNORECASE' is not zero, _all_ regexp and string operations ignore
+case.  Changing the value of `IGNORECASE' dynamically controls the case
+sensitivity of your program as it runs.  Case is significant by default
+because `IGNORECASE' (like most variables) is initialized to zero.
+
+     x = "aB"
+     if (x ~ /ab/) ...   # this test will fail
+     
+     IGNORECASE = 1
+     if (x ~ /ab/) ...   # now it will succeed
+
+   In general, you cannot use `IGNORECASE' to make certain rules
+case-insensitive and other rules case-sensitive, because there is no way
+to set `IGNORECASE' just for the pattern of a particular rule.  To do
+this, you must use character lists or `tolower'.  However, one thing
+you can do only with `IGNORECASE' is turn case-sensitivity on or off
+dynamically for all the rules at once.
+
+   `IGNORECASE' can be set on the command line, or in a `BEGIN' rule
+(*note Other Command Line Arguments: Other Arguments.; also *note
+Startup and Cleanup Actions: Using BEGIN/END.).  Setting `IGNORECASE'
+from the command line is a way to make a program case-insensitive
+without having to edit it.
+
+   Prior to version 3.0 of `gawk', the value of `IGNORECASE' only
+affected regexp operations. It did not affect string comparison with
+`==', `!=', and so on.  Beginning with version 3.0, both regexp and
+string comparison operations are affected by `IGNORECASE'.
+
+   Beginning with version 3.0 of `gawk', the equivalences between
+upper-case and lower-case characters are based on the ISO-8859-1 (ISO
+Latin-1) character set. This character set is a superset of the
+traditional 128 ASCII characters, that also provides a number of
+characters suitable for use with European languages.
+
+   The value of `IGNORECASE' has no effect if `gawk' is in
+compatibility mode (*note Command Line Options: Options.).  Case is
+always significant in compatibility mode.
+
+
+File: gawk.info,  Node: Leftmost Longest,  Next: Computed Regexps,  Prev: Case-sensitivity,  Up: Regexp
+
+How Much Text Matches?
+======================
+
+   Consider the following example:
+
+     echo aaaabcd | awk '{ sub(/a+/, "<A>"); print }'
+
+   This example uses the `sub' function (which we haven't discussed yet,
+*note Built-in Functions for String Manipulation: String Functions.)
+to make a change to the input record. Here, the regexp `/a+/' indicates
+"one or more `a' characters," and the replacement text is `<A>'.
+
+   The input contains four `a' characters.  What will the output be?
+In other words, how many is "one or more"--will `awk' match two, three,
+or all four `a' characters?
+
+   The answer is, `awk' (and POSIX) regular expressions always match
+the leftmost, _longest_ sequence of input characters that can match.
+Thus, in this example, all four `a' characters are replaced with `<A>'.
+
+     $ echo aaaabcd | awk '{ sub(/a+/, "<A>"); print }'
+     -| <A>bcd
+
+   For simple match/no-match tests, this is not so important. But when
+doing regexp-based field and record splitting, and text matching and
+substitutions with the `match', `sub', `gsub', and `gensub' functions,
+it is very important.  *Note Built-in Functions for String
+Manipulation: String Functions, for more information on these functions.
+Understanding this principle is also important for regexp-based record
+and field splitting (*note How Input is Split into Records: Records.,
+and also *note Specifying How Fields are Separated: Field Separators.).
+
+
+File: gawk.info,  Node: Computed Regexps,  Prev: Leftmost Longest,  Up: Regexp
+
+Using Dynamic Regexps
+=====================
+
+   The right hand side of a `~' or `!~' operator need not be a regexp
+constant (i.e. a string of characters between slashes).  It may be any
+expression.  The expression is evaluated, and converted if necessary to
+a string; the contents of the string are used as the regexp.  A regexp
+that is computed in this way is called a "dynamic regexp".  For example:
+
+     BEGIN { identifier_regexp = "[A-Za-z_][A-Za-z_0-9]+" }
+     $0 ~ identifier_regexp    { print }
+
+sets `identifier_regexp' to a regexp that describes `awk' variable
+names, and tests if the input record matches this regexp.
+
+   *Caution:* When using the `~' and `!~' operators, there is a
+difference between a regexp constant enclosed in slashes, and a string
+constant enclosed in double quotes.  If you are going to use a string
+constant, you have to understand that the string is in essence scanned
+_twice_; the first time when `awk' reads your program, and the second
+time when it goes to match the string on the left-hand side of the
+operator with the pattern on the right.  This is true of any string
+valued expression (such as `identifier_regexp' above), not just string
+constants.
+
+   What difference does it make if the string is scanned twice? The
+answer has to do with escape sequences, and particularly with
+backslashes.  To get a backslash into a regular expression inside a
+string, you have to type two backslashes.
+
+   For example, `/\*/' is a regexp constant for a literal `*'.  Only
+one backslash is needed.  To do the same thing with a string, you would
+have to type `"\\*"'.  The first backslash escapes the second one, so
+that the string actually contains the two characters `\' and `*'.
+
+   Given that you can use both regexp and string constants to describe
+regular expressions, which should you use?  The answer is "regexp
+constants," for several reasons.
+
+  1. String constants are more complicated to write, and more difficult
+     to read. Using regexp constants makes your programs less
+     error-prone.  Not understanding the difference between the two
+     kinds of constants is a common source of errors.
+
+  2. It is also more efficient to use regexp constants: `awk' can note
+     that you have supplied a regexp and store it internally in a form
+     that makes pattern matching more efficient.  When using a string
+     constant, `awk' must first convert the string into this internal
+     form, and then perform the pattern matching.
+
+  3. Using regexp constants is better style; it shows clearly that you
+     intend a regexp match.
+
+
+File: gawk.info,  Node: Reading Files,  Next: Printing,  Prev: Regexp,  Up: Top
+
+Reading Input Files
+*******************
+
+   In the typical `awk' program, all input is read either from the
+standard input (by default the keyboard, but often a pipe from another
+command) or from files whose names you specify on the `awk' command
+line.  If you specify input files, `awk' reads them in order, reading
+all the data from one before going on to the next.  The name of the
+current input file can be found in the built-in variable `FILENAME'
+(*note Built-in Variables::).
+
+   The input is read in units called "records", and processed by the
+rules of your program one record at a time.  By default, each record is
+one line.  Each record is automatically split into chunks called
+"fields".  This makes it more convenient for programs to work on the
+parts of a record.
+
+   On rare occasions you will need to use the `getline' command.  The
+`getline' command is valuable, both because it can do explicit input
+from any number of files, and because the files used with it do not
+have to be named on the `awk' command line (*note Explicit Input with
+`getline': Getline.).
+
+* Menu:
+
+* Records::                     Controlling how data is split into records.
+* Fields::                      An introduction to fields.
+* Non-Constant Fields::         Non-constant Field Numbers.
+* Changing Fields::             Changing the Contents of a Field.
+* Field Separators::            The field separator and how to change it.
+* Constant Size::               Reading constant width data.
+* Multiple Line::               Reading multi-line records.
+* Getline::                     Reading files under explicit program control
+                                using the `getline' function.
+
+
+File: gawk.info,  Node: Records,  Next: Fields,  Prev: Reading Files,  Up: Reading Files
+
+How Input is Split into Records
+===============================
+
+   The `awk' utility divides the input for your `awk' program into
+records and fields.  Records are separated by a character called the
+"record separator".  By default, the record separator is the newline
+character.  This is why records are, by default, single lines.  You can
+use a different character for the record separator by assigning the
+character to the built-in variable `RS'.
+
+   You can change the value of `RS' in the `awk' program, like any
+other variable, with the assignment operator, `=' (*note Assignment
+Expressions: Assignment Ops.).  The new record-separator character
+should be enclosed in quotation marks, which indicate a string
+constant.  Often the right time to do this is at the beginning of
+execution, before any input has been processed, so that the very first
+record will be read with the proper separator.  To do this, use the
+special `BEGIN' pattern (*note The `BEGIN' and `END' Special Patterns:
+BEGIN/END.).  For example:
+
+     awk 'BEGIN { RS = "/" } ; { print $0 }' BBS-list
+
+changes the value of `RS' to `"/"', before reading any input.  This is
+a string whose first character is a slash; as a result, records are
+separated by slashes.  Then the input file is read, and the second rule
+in the `awk' program (the action with no pattern) prints each record.
+Since each `print' statement adds a newline at the end of its output,
+the effect of this `awk' program is to copy the input with each slash
+changed to a newline.  Here are the results of running the program on
+`BBS-list':
+
+     $ awk 'BEGIN { RS = "/" } ; { print $0 }' BBS-list
+     -| aardvark     555-5553     1200
+     -| 300          B
+     -| alpo-net     555-3412     2400
+     -| 1200
+     -| 300     A
+     -| barfly       555-7685     1200
+     -| 300          A
+     -| bites        555-1675     2400
+     -| 1200
+     -| 300     A
+     -| camelot      555-0542     300               C
+     -| core         555-2912     1200
+     -| 300          C
+     -| fooey        555-1234     2400
+     -| 1200
+     -| 300     B
+     -| foot         555-6699     1200
+     -| 300          B
+     -| macfoo       555-6480     1200
+     -| 300          A
+     -| sdace        555-3430     2400
+     -| 1200
+     -| 300     A
+     -| sabafoo      555-2127     1200
+     -| 300          C
+     -|
+
+Note that the entry for the `camelot' BBS is not split.  In the
+original data file (*note Data Files for the Examples: Sample Data
+Files.), the line looks like this:
+
+     camelot      555-0542     300               C
+
+It only has one baud rate; there are no slashes in the record.
+
+   Another way to change the record separator is on the command line,
+using the variable-assignment feature (*note Other Command Line
+Arguments: Other Arguments.).
+
+     awk '{ print $0 }' RS="/" BBS-list
+
+This sets `RS' to `/' before processing `BBS-list'.
+
+   Using an unusual character such as `/' for the record separator
+produces correct behavior in the vast majority of cases.  However, the
+following (extreme) pipeline prints a surprising `1'.  There is one
+field, consisting of a newline.  The value of the built-in variable
+`NF' is the number of fields in the current record.
+
+     $ echo | awk 'BEGIN { RS = "a" } ; { print NF }'
+     -| 1
+
+Reaching the end of an input file terminates the current input record,
+even if the last character in the file is not the character in `RS'
+(d.c.).
+
+   The empty string, `""' (a string of no characters), has a special
+meaning as the value of `RS': it means that records are separated by
+one or more blank lines, and nothing else.  *Note Multiple-Line
+Records: Multiple Line, for more details.
+
+   If you change the value of `RS' in the middle of an `awk' run, the
+new value is used to delimit subsequent records, but the record
+currently being processed (and records already processed) are not
+affected.
+
+   After the end of the record has been determined, `gawk' sets the
+variable `RT' to the text in the input that matched `RS'.
+
+   The value of `RS' is in fact not limited to a one-character string.
+It can be any regular expression (*note Regular Expressions: Regexp.).
+In general, each record ends at the next string that matches the
+regular expression; the next record starts at the end of the matching
+string.  This general rule is actually at work in the usual case, where
+`RS' contains just a newline: a record ends at the beginning of the
+next matching string (the next newline in the input) and the following
+record starts just after the end of this string (at the first character
+of the following line).  The newline, since it matches `RS', is not
+part of either record.
+
+   When `RS' is a single character, `RT' will contain the same single
+character. However, when `RS' is a regular expression, then `RT'
+becomes more useful; it contains the actual input text that matched the
+regular expression.
+
+   The following example illustrates both of these features.  It sets
+`RS' equal to a regular expression that matches either a newline, or a
+series of one or more upper-case letters with optional leading and/or
+trailing white space (*note Regular Expressions: Regexp.).
+
+     $ echo record 1 AAAA record 2 BBBB record 3 |
+     > gawk 'BEGIN { RS = "\n|( *[[:upper:]]+ *)" }
+     >             { print "Record =", $0, "and RT =", RT }'
+     -| Record = record 1 and RT =  AAAA
+     -| Record = record 2 and RT =  BBBB
+     -| Record = record 3 and RT =
+     -|
+
+The final line of output has an extra blank line. This is because the
+value of `RT' is a newline, and then the `print' statement supplies its
+own terminating newline.
+
+   *Note A Simple Stream Editor: Simple Sed, for a more useful example
+of `RS' as a regexp and `RT'.
+
+   The use of `RS' as a regular expression and the `RT' variable are
+`gawk' extensions; they are not available in compatibility mode (*note
+Command Line Options: Options.).  In compatibility mode, only the first
+character of the value of `RS' is used to determine the end of the
+record.
+
+   The `awk' utility keeps track of the number of records that have
+been read so far from the current input file.  This value is stored in a
+built-in variable called `FNR'.  It is reset to zero when a new file is
+started.  Another built-in variable, `NR', is the total number of input
+records read so far from all data files.  It starts at zero but is
+never automatically reset to zero.
+
+
+File: gawk.info,  Node: Fields,  Next: Non-Constant Fields,  Prev: Records,  Up: Reading Files
+
+Examining Fields
+================
+
+   When `awk' reads an input record, the record is automatically
+separated or "parsed" by the interpreter into chunks called "fields".
+By default, fields are separated by whitespace, like words in a line.
+Whitespace in `awk' means any string of one or more spaces, tabs or
+newlines;(1) other characters such as formfeed, and so on, that are
+considered whitespace by other languages are _not_ considered
+whitespace by `awk'.
+
+   The purpose of fields is to make it more convenient for you to refer
+to these pieces of the record.  You don't have to use them--you can
+operate on the whole record if you wish--but fields are what make
+simple `awk' programs so powerful.
+
+   To refer to a field in an `awk' program, you use a dollar-sign, `$',
+followed by the number of the field you want.  Thus, `$1' refers to the
+first field, `$2' to the second, and so on.  For example, suppose the
+following is a line of input:
+
+     This seems like a pretty nice example.
+
+Here the first field, or `$1', is `This'; the second field, or `$2', is
+`seems'; and so on.  Note that the last field, `$7', is `example.'.
+Because there is no space between the `e' and the `.', the period is
+considered part of the seventh field.
+
+   `NF' is a built-in variable whose value is the number of fields in
+the current record.  `awk' updates the value of `NF' automatically,
+each time a record is read.
+
+   No matter how many fields there are, the last field in a record can
+be represented by `$NF'.  So, in the example above, `$NF' would be the
+same as `$7', which is `example.'.  Why this works is explained below
+(*note Non-constant Field Numbers: Non-Constant Fields.).  If you try
+to reference a field beyond the last one, such as `$8' when the record
+has only seven fields, you get the empty string.
+
+   `$0', which looks like a reference to the "zeroth" field, is a
+special case: it represents the whole input record.  `$0' is used when
+you are not interested in fields.
+
+   Here are some more examples:
+
+     $ awk '$1 ~ /foo/ { print $0 }' BBS-list
+     -| fooey        555-1234     2400/1200/300     B
+     -| foot         555-6699     1200/300          B
+     -| macfoo       555-6480     1200/300          A
+     -| sabafoo      555-2127     1200/300          C
+
+This example prints each record in the file `BBS-list' whose first
+field contains the string `foo'.  The operator `~' is called a
+"matching operator" (*note How to Use Regular Expressions: Regexp
+Usage.); it tests whether a string (here, the field `$1') matches a
+given regular expression.
+
+   By contrast, the following example looks for `foo' in _the entire
+record_ and prints the first field and the last field for each input
+record containing a match.
+
+     $ awk '/foo/ { print $1, $NF }' BBS-list
+     -| fooey B
+     -| foot B
+     -| macfoo A
+     -| sabafoo C
+
+   ---------- Footnotes ----------
+
+   (1) In POSIX `awk', newlines are not considered whitespace for
+separating fields.
+
+
+File: gawk.info,  Node: Non-Constant Fields,  Next: Changing Fields,  Prev: Fields,  Up: Reading Files
+
+Non-constant Field Numbers
+==========================
+
+   The number of a field does not need to be a constant.  Any
+expression in the `awk' language can be used after a `$' to refer to a
+field.  The value of the expression specifies the field number.  If the
+value is a string, rather than a number, it is converted to a number.
+Consider this example:
+
+     awk '{ print $NR }'
+
+Recall that `NR' is the number of records read so far: one in the first
+record, two in the second, etc.  So this example prints the first field
+of the first record, the second field of the second record, and so on.
+For the twentieth record, field number 20 is printed; most likely, the
+record has fewer than 20 fields, so this prints a blank line.
+
+   Here is another example of using expressions as field numbers:
+
+     awk '{ print $(2*2) }' BBS-list
+
+   `awk' must evaluate the expression `(2*2)' and use its value as the
+number of the field to print.  The `*' sign represents multiplication,
+so the expression `2*2' evaluates to four.  The parentheses are used so
+that the multiplication is done before the `$' operation; they are
+necessary whenever there is a binary operator in the field-number
+expression.  This example, then, prints the hours of operation (the
+fourth field) for every line of the file `BBS-list'.  (All of the `awk'
+operators are listed, in order of decreasing precedence, in *Note
+Operator Precedence (How Operators Nest): Precedence.)
+
+   If the field number you compute is zero, you get the entire record.
+Thus, `$(2-2)' has the same value as `$0'.  Negative field numbers are
+not allowed; trying to reference one will usually terminate your
+running `awk' program.  (The POSIX standard does not define what
+happens when you reference a negative field number.  `gawk' will notice
+this and terminate your program.  Other `awk' implementations may
+behave differently.)
+
+   As mentioned in *Note Examining Fields: Fields, the number of fields
+in the current record is stored in the built-in variable `NF' (also
+*note Built-in Variables::).  The expression `$NF' is not a special
+feature: it is the direct consequence of evaluating `NF' and using its
+value as a field number.
+
+
+File: gawk.info,  Node: Changing Fields,  Next: Field Separators,  Prev: Non-Constant Fields,  Up: Reading Files
+
+Changing the Contents of a Field
+================================
+
+   You can change the contents of a field as seen by `awk' within an
+`awk' program; this changes what `awk' perceives as the current input
+record.  (The actual input is untouched; `awk' _never_ modifies the
+input file.)
+
+   Consider this example and its output:
+
+     $ awk '{ $3 = $2 - 10; print $2, $3 }' inventory-shipped
+     -| 13 3
+     -| 15 5
+     -| 15 5
+     ...
+
+The `-' sign represents subtraction, so this program reassigns field
+three, `$3', to be the value of field two minus ten, `$2 - 10'.  (*Note
+Arithmetic Operators: Arithmetic Ops.)  Then field two, and the new
+value for field three, are printed.
+
+   In order for this to work, the text in field `$2' must make sense as
+a number; the string of characters must be converted to a number in
+order for the computer to do arithmetic on it.  The number resulting
+from the subtraction is converted back to a string of characters which
+then becomes field three.  *Note Conversion of Strings and Numbers:
+Conversion.
+
+   When you change the value of a field (as perceived by `awk'), the
+text of the input record is recalculated to contain the new field where
+the old one was.  Therefore, `$0' changes to reflect the altered field.
+Thus, this program prints a copy of the input file, with 10 subtracted
+from the second field of each line.
+
+     $ awk '{ $2 = $2 - 10; print $0 }' inventory-shipped
+     -| Jan 3 25 15 115
+     -| Feb 5 32 24 226
+     -| Mar 5 24 34 228
+     ...
+
+   You can also assign contents to fields that are out of range.  For
+example:
+
+     $ awk '{ $6 = ($5 + $4 + $3 + $2)
+     >        print $6 }' inventory-shipped
+     -| 168
+     -| 297
+     -| 301
+     ...
+
+We've just created `$6', whose value is the sum of fields `$2', `$3',
+`$4', and `$5'.  The `+' sign represents addition.  For the file
+`inventory-shipped', `$6' represents the total number of parcels
+shipped for a particular month.
+
+   Creating a new field changes `awk''s internal copy of the current
+input record--the value of `$0'.  Thus, if you do `print $0' after
+adding a field, the record printed includes the new field, with the
+appropriate number of field separators between it and the previously
+existing fields.
+
+   This recomputation affects and is affected by `NF' (the number of
+fields; *note Examining Fields: Fields.), and by a feature that has not
+been discussed yet, the "output field separator", `OFS', which is used
+to separate the fields (*note Output Separators::).  For example, the
+value of `NF' is set to the number of the highest field you create.
+
+   Note, however, that merely _referencing_ an out-of-range field does
+_not_ change the value of either `$0' or `NF'.  Referencing an
+out-of-range field only produces an empty string.  For example:
+
+     if ($(NF+1) != "")
+         print "can't happen"
+     else
+         print "everything is normal"
+
+should print `everything is normal', because `NF+1' is certain to be
+out of range.  (*Note The `if'-`else' Statement: If Statement, for more
+information about `awk''s `if-else' statements.  *Note Variable Typing
+and Comparison Expressions: Typing and Comparison, for more information
+about the `!=' operator.)
+
+   It is important to note that making an assignment to an existing
+field will change the value of `$0', but will not change the value of
+`NF', even when you assign the empty string to a field.  For example:
+
+     $ echo a b c d | awk '{ OFS = ":"; $2 = ""
+     >                       print $0; print NF }'
+     -| a::c:d
+     -| 4
+
+The field is still there; it just has an empty value.  You can tell
+because there are two colons in a row.
+
+   This example shows what happens if you create a new field.
+
+     $ echo a b c d | awk '{ OFS = ":"; $2 = ""; $6 = "new"
+     >                       print $0; print NF }'
+     -| a::c:d::new
+     -| 6
+
+The intervening field, `$5' is created with an empty value (indicated
+by the second pair of adjacent colons), and `NF' is updated with the
+value six.
+
+   Finally, decrementing `NF' will lose the values of the fields after
+the new value of `NF', and `$0' will be recomputed.  Here is an example:
+
+     $ echo a b c d e f | ../gawk '{ print "NF =", NF;
+     >                               NF = 3; print $0 }'
+     -| NF = 6
+     -| a b c
+
+
+File: gawk.info,  Node: Field Separators,  Next: Constant Size,  Prev: Changing Fields,  Up: Reading Files
+
+Specifying How Fields are Separated
+===================================
+
+   This section is rather long; it describes one of the most fundamental
+operations in `awk'.
+
+* Menu:
+
+* Basic Field Splitting::        How fields are split with single characters
+                                 or simple strings.
+* Regexp Field Splitting::       Using regexps as the field separator.
+* Single Character Fields::      Making each character a separate field.
+* Command Line Field Separator:: Setting `FS' from the command line.
+* Field Splitting Summary::      Some final points and a summary table.
+
+
+File: gawk.info,  Node: Basic Field Splitting,  Next: Regexp Field Splitting,  Prev: Field Separators,  Up: Field Separators
+
+The Basics of Field Separating
+------------------------------
+
+   The "field separator", which is either a single character or a
+regular expression, controls the way `awk' splits an input record into
+fields.  `awk' scans the input record for character sequences that
+match the separator; the fields themselves are the text between the
+matches.
+
+   In the examples below, we use the bullet symbol "*" to represent
+spaces in the output.
+
+   If the field separator is `oo', then the following line:
+
+     moo goo gai pan
+
+would be split into three fields: `m', `*g' and `*gai*pan'.  Note the
+leading spaces in the values of the second and third fields.
+
+   The field separator is represented by the built-in variable `FS'.
+Shell programmers take note!  `awk' does _not_ use the name `IFS' which
+is used by the POSIX compatible shells (such as the Bourne shell, `sh',
+or the GNU Bourne-Again Shell, Bash).
+
+   You can change the value of `FS' in the `awk' program with the
+assignment operator, `=' (*note Assignment Expressions: Assignment
+Ops.).  Often the right time to do this is at the beginning of
+execution, before any input has been processed, so that the very first
+record will be read with the proper separator.  To do this, use the
+special `BEGIN' pattern (*note The `BEGIN' and `END' Special Patterns:
+BEGIN/END.).  For example, here we set the value of `FS' to the string
+`","':
+
+     awk 'BEGIN { FS = "," } ; { print $2 }'
+
+Given the input line,
+
+     John Q. Smith, 29 Oak St., Walamazoo, MI 42139
+
+this `awk' program extracts and prints the string `*29*Oak*St.'.
+
+   Sometimes your input data will contain separator characters that
+don't separate fields the way you thought they would.  For instance, the
+person's name in the example we just used might have a title or suffix
+attached, such as `John Q. Smith, LXIX'.  From input containing such a
+name:
+
+     John Q. Smith, LXIX, 29 Oak St., Walamazoo, MI 42139
+
+the above program would extract `*LXIX', instead of `*29*Oak*St.'.  If
+you were expecting the program to print the address, you would be
+surprised.  The moral is: choose your data layout and separator
+characters carefully to prevent such problems.
+
+   Normally, fields are separated by whitespace sequences (spaces, tabs
+and newlines), not by single spaces: two spaces in a row do not delimit
+an empty field.  The default value of the field separator `FS' is a
+string containing a single space, `" "'.  If this value were
+interpreted in the usual way, each space character would separate
+fields, so two spaces in a row would make an empty field between them.
+The reason this does not happen is that a single space as the value of
+`FS' is a special case: it is taken to specify the default manner of
+delimiting fields.
+
+   If `FS' is any other single character, such as `","', then each
+occurrence of that character separates two fields.  Two consecutive
+occurrences delimit an empty field.  If the character occurs at the
+beginning or the end of the line, that too delimits an empty field.  The
+space character is the only single character which does not follow these
+rules.
+
+
+File: gawk.info,  Node: Regexp Field Splitting,  Next: Single Character Fields,  Prev: Basic Field Splitting,  Up: Field Separators
+
+Using Regular Expressions to Separate Fields
+--------------------------------------------
+
+   The previous node discussed the use of single characters or simple
+strings as the value of `FS'.  More generally, the value of `FS' may be
+a string containing any regular expression.  In this case, each match
+in the record for the regular expression separates fields.  For
+example, the assignment:
+
+     FS = ", \t"
+
+makes every area of an input line that consists of a comma followed by a
+space and a tab, into a field separator.  (`\t' is an "escape sequence"
+that stands for a tab; *note Escape Sequences::, for the complete list
+of similar escape sequences.)
+
+   For a less trivial example of a regular expression, suppose you want
+single spaces to separate fields the way single commas were used above.
+You can set `FS' to `"[ ]"' (left bracket, space, right bracket).  This
+regular expression matches a single space and nothing else (*note
+Regular Expressions: Regexp.).
+
+   There is an important difference between the two cases of `FS = " "'
+(a single space) and `FS = "[ \t\n]+"' (left bracket, space, backslash,
+"t", backslash, "n", right bracket, which is a regular expression
+matching one or more spaces, tabs, or newlines).  For both values of
+`FS', fields are separated by runs of spaces, tabs and/or newlines.
+However, when the value of `FS' is `" "', `awk' will first strip
+leading and trailing whitespace from the record, and then decide where
+the fields are.
+
+   For example, the following pipeline prints `b':
+
+     $ echo ' a b c d ' | awk '{ print $2 }'
+     -| b
+
+However, this pipeline prints `a' (note the extra spaces around each
+letter):
+
+     $ echo ' a  b  c  d ' | awk 'BEGIN { FS = "[ \t]+" }
+     >                                  { print $2 }'
+     -| a
+
+In this case, the first field is "null", or empty.
+
+   The stripping of leading and trailing whitespace also comes into
+play whenever `$0' is recomputed.  For instance, study this pipeline:
+
+     $ echo '   a b c d' | awk '{ print; $2 = $2; print }'
+     -|    a b c d
+     -| a b c d
+
+The first `print' statement prints the record as it was read, with
+leading whitespace intact.  The assignment to `$2' rebuilds `$0' by
+concatenating `$1' through `$NF' together, separated by the value of
+`OFS'.  Since the leading whitespace was ignored when finding `$1', it
+is not part of the new `$0'.  Finally, the last `print' statement
+prints the new `$0'.
+
+
+File: gawk.info,  Node: Single Character Fields,  Next: Command Line Field Separator,  Prev: Regexp Field Splitting,  Up: Field Separators
+
+Making Each Character a Separate Field
+--------------------------------------
+
+   There are times when you may want to examine each character of a
+record separately.  In `gawk', this is easy to do, you simply assign
+the null string (`""') to `FS'. In this case, each individual character
+in the record will become a separate field.  Here is an example:
+
+     echo a b | gawk 'BEGIN { FS = "" }
+                      {
+                          for (i = 1; i <= NF; i = i + 1)
+                              print "Field", i, "is", $i
+                      }'
+
+The output from this is:
+
+     Field 1 is a
+     Field 2 is
+     Field 3 is b
+
+   Traditionally, the behavior for `FS' equal to `""' was not defined.
+In this case, Unix `awk' would simply treat the entire record as only
+having one field (d.c.).  In compatibility mode (*note Command Line
+Options: Options.), if `FS' is the null string, then `gawk' will also
+behave this way.
+
+
+File: gawk.info,  Node: Command Line Field Separator,  Next: Field Splitting Summary,  Prev: Single Character Fields,  Up: Field Separators
+
+Setting `FS' from the Command Line
+----------------------------------
+
+   `FS' can be set on the command line.  You use the `-F' option to do
+so.  For example:
+
+     awk -F, 'PROGRAM' INPUT-FILES
+
+sets `FS' to be the `,' character.  Notice that the option uses a
+capital `F'.  Contrast this with `-f', which specifies a file
+containing an `awk' program.  Case is significant in command line
+options: the `-F' and `-f' options have nothing to do with each other.
+You can use both options at the same time to set the `FS' variable
+_and_ get an `awk' program from a file.
+
+   The value used for the argument to `-F' is processed in exactly the
+same way as assignments to the built-in variable `FS'.  This means that
+if the field separator contains special characters, they must be escaped
+appropriately.  For example, to use a `\' as the field separator, you
+would have to type:
+
+     # same as FS = "\\"
+     awk -F\\\\ '...' files ...
+
+Since `\' is used for quoting in the shell, `awk' will see `-F\\'.
+Then `awk' processes the `\\' for escape characters (*note Escape
+Sequences::), finally yielding a single `\' to be used for the field
+separator.
+
+   As a special case, in compatibility mode (*note Command Line
+Options: Options.), if the argument to `-F' is `t', then `FS' is set to
+the tab character.  This is because if you type `-F\t' at the shell,
+without any quotes, the `\' gets deleted, so `awk' figures that you
+really want your fields to be separated with tabs, and not `t's.  Use
+`-v FS="t"' on the command line if you really do want to separate your
+fields with `t's (*note Command Line Options: Options.).
+
+   For example, let's use an `awk' program file called `baud.awk' that
+contains the pattern `/300/', and the action `print $1'.  Here is the
+program:
+
+     /300/   { print $1 }
+
+   Let's also set `FS' to be the `-' character, and run the program on
+the file `BBS-list'.  The following command prints a list of the names
+of the bulletin boards that operate at 300 baud and the first three
+digits of their phone numbers:
+
+     $ awk -F- -f baud.awk BBS-list
+     -| aardvark     555
+     -| alpo
+     -| barfly       555
+     ...
+
+Note the second line of output.  In the original file (*note Data Files
+for the Examples: Sample Data Files.), the second line looked like this:
+
+     alpo-net     555-3412     2400/1200/300     A
+
+   The `-' as part of the system's name was used as the field
+separator, instead of the `-' in the phone number that was originally
+intended.  This demonstrates why you have to be careful in choosing
+your field and record separators.
+
+   On many Unix systems, each user has a separate entry in the system
+password file, one line per user.  The information in these lines is
+separated by colons.  The first field is the user's logon name, and the
+second is the user's encrypted password.  A password file entry might
+look like this:
+
+     arnold:xyzzy:2076:10:Arnold Robbins:/home/arnold:/bin/sh
+
+   The following program searches the system password file, and prints
+the entries for users who have no password:
+
+     awk -F: '$2 == ""' /etc/passwd
+
+
+File: gawk.info,  Node: Field Splitting Summary,  Prev: Command Line Field Separator,  Up: Field Separators
+
+Field Splitting Summary
+-----------------------
+
+   According to the POSIX standard, `awk' is supposed to behave as if
+each record is split into fields at the time that it is read.  In
+particular, this means that you can change the value of `FS' after a
+record is read, and the value of the fields (i.e. how they were split)
+should reflect the old value of `FS', not the new one.
+
+   However, many implementations of `awk' do not work this way.
+Instead, they defer splitting the fields until a field is actually
+referenced.  The fields will be split using the _current_ value of
+`FS'! (d.c.)  This behavior can be difficult to diagnose. The following
+example illustrates the difference between the two methods.  (The
+`sed'(1) command prints just the first line of `/etc/passwd'.)
+
+     sed 1q /etc/passwd | awk '{ FS = ":" ; print $1 }'
+
+will usually print
+
+     root
+
+on an incorrect implementation of `awk', while `gawk' will print
+something like
+
+     root:nSijPlPhZZwgE:0:0:Root:/:
+
+   The following table summarizes how fields are split, based on the
+value of `FS'. (`==' means "is equal to.")
+
+`FS == " "'
+     Fields are separated by runs of whitespace.  Leading and trailing
+     whitespace are ignored.  This is the default.
+
+`FS == ANY OTHER SINGLE CHARACTER'
+     Fields are separated by each occurrence of the character.  Multiple
+     successive occurrences delimit empty fields, as do leading and
+     trailing occurrences.  The character can even be a regexp
+     metacharacter; it does not need to be escaped.
+
+`FS == REGEXP'
+     Fields are separated by occurrences of characters that match
+     REGEXP.  Leading and trailing matches of REGEXP delimit empty
+     fields.
+
+`FS == ""'
+     Each individual character in the record becomes a separate field.
+
+   ---------- Footnotes ----------
+
+   (1) The `sed' utility is a "stream editor."  Its behavior is also
+defined by the POSIX standard.
+
+
+File: gawk.info,  Node: Constant Size,  Next: Multiple Line,  Prev: Field Separators,  Up: Reading Files
+
+Reading Fixed-width Data
+========================
+
+   (This section discusses an advanced, experimental feature.  If you
+are a novice `awk' user, you may wish to skip it on the first reading.)
+
+   `gawk' version 2.13 introduced a new facility for dealing with
+fixed-width fields with no distinctive field separator.  Data of this
+nature arises, for example, in  the input for old FORTRAN programs where
+numbers are run together; or in the output of programs that did not
+anticipate the use of their output as input for other programs.
+
+   An example of the latter is a table where all the columns are lined
+up by the use of a variable number of spaces and _empty fields are just
+spaces_.  Clearly, `awk''s normal field splitting based on `FS' will
+not work well in this case.  Although a portable `awk' program can use
+a series of `substr' calls on `$0' (*note Built-in Functions for String
+Manipulation: String Functions.), this is awkward and inefficient for a
+large number of fields.
+
+   The splitting of an input record into fixed-width fields is
+specified by assigning a string containing space-separated numbers to
+the built-in variable `FIELDWIDTHS'.  Each number specifies the width
+of the field _including_ columns between fields.  If you want to ignore
+the columns between fields, you can specify the width as a separate
+field that is subsequently ignored.
+
+   The following data is the output of the Unix `w' utility.  It is
+useful to illustrate the use of `FIELDWIDTHS'.
+
+      10:06pm  up 21 days, 14:04,  23 users
+     User     tty       login  idle   JCPU   PCPU  what
+     hzuo     ttyV0     8:58pm            9      5  vi p24.tex
+     hzang    ttyV3     6:37pm    50                -csh
+     eklye    ttyV5     9:53pm            7      1  em thes.tex
+     dportein ttyV6     8:17pm  1:47                -csh
+     gierd    ttyD3    10:00pm     1                elm
+     dave     ttyD4     9:47pm            4      4  w
+     brent    ttyp0    26Jun91  4:46  26:46   4:41  bash
+     dave     ttyq4    26Jun9115days     46     46  wnewmail
+
+   The following program takes the above input, converts the idle time
+to number of seconds and prints out the first two fields and the
+calculated idle time.  (This program uses a number of `awk' features
+that haven't been introduced yet.)
+
+     BEGIN  { FIELDWIDTHS = "9 6 10 6 7 7 35" }
+     NR > 2 {
+         idle = $4
+         sub(/^  */, "", idle)   # strip leading spaces
+         if (idle == "")
+             idle = 0
+         if (idle ~ /:/) {
+             split(idle, t, ":")
+             idle = t[1] * 60 + t[2]
+         }
+         if (idle ~ /days/)
+             idle *= 24 * 60 * 60
+     
+         print $1, $2, idle
+     }
+
+   Here is the result of running the program on the data:
+
+     hzuo      ttyV0  0
+     hzang     ttyV3  50
+     eklye     ttyV5  0
+     dportein  ttyV6  107
+     gierd     ttyD3  1
+     dave      ttyD4  0
+     brent     ttyp0  286
+     dave      ttyq4  1296000
+
+   Another (possibly more practical) example of fixed-width input data
+would be the input from a deck of balloting cards.  In some parts of
+the United States, voters mark their choices by punching holes in
+computer cards.  These cards are then processed to count the votes for
+any particular candidate or on any particular issue.  Since a voter may
+choose not to vote on some issue, any column on the card may be empty.
+An `awk' program for processing such data could use the `FIELDWIDTHS'
+feature to simplify reading the data.  (Of course, getting `gawk' to
+run on a system with card readers is another story!)
+
+   Assigning a value to `FS' causes `gawk' to return to using `FS' for
+field splitting.  Use `FS = FS' to make this happen, without having to
+know the current value of `FS'.
+
+   This feature is still experimental, and may evolve over time.  Note
+that in particular, `gawk' does not attempt to verify the sanity of the
+values used in the value of `FIELDWIDTHS'.
+
+
+File: gawk.info,  Node: Multiple Line,  Next: Getline,  Prev: Constant Size,  Up: Reading Files
+
+Multiple-Line Records
+=====================
+
+   In some data bases, a single line cannot conveniently hold all the
+information in one entry.  In such cases, you can use multi-line
+records.
+
+   The first step in doing this is to choose your data format: when
+records are not defined as single lines, how do you want to define them?
+What should separate records?
+
+   One technique is to use an unusual character or string to separate
+records.  For example, you could use the formfeed character (written
+`\f' in `awk', as in C) to separate them, making each record a page of
+the file.  To do this, just set the variable `RS' to `"\f"' (a string
+containing the formfeed character).  Any other character could equally
+well be used, as long as it won't be part of the data in a record.
+
+   Another technique is to have blank lines separate records.  By a
+special dispensation, an empty string as the value of `RS' indicates
+that records are separated by one or more blank lines.  If you set `RS'
+to the empty string, a record always ends at the first blank line
+encountered.  And the next record doesn't start until the first
+non-blank line that follows--no matter how many blank lines appear in a
+row, they are considered one record-separator.
+
+   You can achieve the same effect as `RS = ""' by assigning the string
+`"\n\n+"' to `RS'. This regexp matches the newline at the end of the
+record, and one or more blank lines after the record.  In addition, a
+regular expression always matches the longest possible sequence when
+there is a choice (*note How Much Text Matches?: Leftmost Longest.)  So
+the next record doesn't start until the first non-blank line that
+follows--no matter how many blank lines appear in a row, they are
+considered one record-separator.
+
+   There is an important difference between `RS = ""' and `RS =
+"\n\n+"'. In the first case, leading newlines in the input data file
+are ignored, and if a file ends without extra blank lines after the
+last record, the final newline is removed from the record.  In the
+second case, this special processing is not done (d.c.).
+
+   Now that the input is separated into records, the second step is to
+separate the fields in the record.  One way to do this is to divide each
+of the lines into fields in the normal manner.  This happens by default
+as the result of a special feature: when `RS' is set to the empty
+string, the newline character _always_ acts as a field separator.  This
+is in addition to whatever field separations result from `FS'.
+
+   The original motivation for this special exception was probably to
+provide useful behavior in the default case (i.e. `FS' is equal to
+`" "').  This feature can be a problem if you really don't want the
+newline character to separate fields, since there is no way to prevent
+it.  However, you can work around this by using the `split' function to
+break up the record manually (*note Built-in Functions for String
+Manipulation: String Functions.).
+
+   Another way to separate fields is to put each field on a separate
+line: to do this, just set the variable `FS' to the string `"\n"'.
+(This simple regular expression matches a single newline.)
+
+   A practical example of a data file organized this way might be a
+mailing list, where each entry is separated by blank lines.  If we have
+a mailing list in a file named `addresses', that looks like this:
+
+     Jane Doe
+     123 Main Street
+     Anywhere, SE 12345-6789
+     
+     John Smith
+     456 Tree-lined Avenue
+     Smallville, MW 98765-4321
+     
+     ...
+
+A simple program to process this file would look like this:
+
+     # addrs.awk --- simple mailing list program
+     
+     # Records are separated by blank lines.
+     # Each line is one field.
+     BEGIN { RS = "" ; FS = "\n" }
+     
+     {
+           print "Name is:", $1
+           print "Address is:", $2
+           print "City and State are:", $3
+           print ""
+     }
+
+   Running the program produces the following output:
+
+     $ awk -f addrs.awk addresses
+     -| Name is: Jane Doe
+     -| Address is: 123 Main Street
+     -| City and State are: Anywhere, SE 12345-6789
+     -|
+     -| Name is: John Smith
+     -| Address is: 456 Tree-lined Avenue
+     -| City and State are: Smallville, MW 98765-4321
+     -|
+     ...
+
+   *Note Printing Mailing Labels: Labels Program, for a more realistic
+program that deals with address lists.
+
+   The following table summarizes how records are split, based on the
+value of `RS'. (`==' means "is equal to.")
+
+`RS == "\n"'
+     Records are separated by the newline character (`\n').  In effect,
+     every line in the data file is a separate record, including blank
+     lines.  This is the default.
+
+`RS == ANY SINGLE CHARACTER'
+     Records are separated by each occurrence of the character.
+     Multiple successive occurrences delimit empty records.
+
+`RS == ""'
+     Records are separated by runs of blank lines.  The newline
+     character always serves as a field separator, in addition to
+     whatever value `FS' may have. Leading and trailing newlines in a
+     file are ignored.
+
+`RS == REGEXP'
+     Records are separated by occurrences of characters that match
+     REGEXP.  Leading and trailing matches of REGEXP delimit empty
+     records.
+
+   In all cases, `gawk' sets `RT' to the input text that matched the
+value specified by `RS'.
+
+
+File: gawk.info,  Node: Getline,  Prev: Multiple Line,  Up: Reading Files
+
+Explicit Input with `getline'
+=============================
+
+   So far we have been getting our input data from `awk''s main input
+stream--either the standard input (usually your terminal, sometimes the
+output from another program) or from the files specified on the command
+line.  The `awk' language has a special built-in command called
+`getline' that can be used to read input under your explicit control.
+
+* Menu:
+
+* Getline Intro::            Introduction to the `getline' function.
+* Plain Getline::            Using `getline' with no arguments.
+* Getline/Variable::         Using `getline' into a variable.
+* Getline/File::             Using `getline' from a file.
+* Getline/Variable/File::    Using `getline' into a variable from a
+                             file.
+* Getline/Pipe::             Using `getline' from a pipe.
+* Getline/Variable/Pipe::    Using `getline' into a variable from a
+                             pipe.
+* Getline Summary::          Summary Of `getline' Variants.
+
+
+File: gawk.info,  Node: Getline Intro,  Next: Plain Getline,  Prev: Getline,  Up: Getline
+
+Introduction to `getline'
+-------------------------
+
+   This command is used in several different ways, and should _not_ be
+used by beginners.  It is covered here because this is the chapter on
+input.  The examples that follow the explanation of the `getline'
+command include material that has not been covered yet.  Therefore,
+come back and study the `getline' command _after_ you have reviewed the
+rest of this Info file and have a good knowledge of how `awk' works.
+
+   `getline' returns one if it finds a record, and zero if the end of
+the file is encountered.  If there is some error in getting a record,
+such as a file that cannot be opened, then `getline' returns -1.  In
+this case, `gawk' sets the variable `ERRNO' to a string describing the
+error that occurred.
+
+   In the following examples, COMMAND stands for a string value that
+represents a shell command.
+
+
+File: gawk.info,  Node: Plain Getline,  Next: Getline/Variable,  Prev: Getline Intro,  Up: Getline
+
+Using `getline' with No Arguments
+---------------------------------
+
+   The `getline' command can be used without arguments to read input
+from the current input file.  All it does in this case is read the next
+input record and split it up into fields.  This is useful if you've
+finished processing the current record, but you want to do some special
+processing _right now_ on the next record.  Here's an example:
+
+     awk '{
+          if ((t = index($0, "/*")) != 0) {
+               # value will be "" if t is 1
+               tmp = substr($0, 1, t - 1)
+               u = index(substr($0, t + 2), "*/")
+               while (u == 0) {
+                    if (getline <= 0) {
+                         m = "unexpected EOF or error"
+                         m = (m ": " ERRNO)
+                         print m > "/dev/stderr"
+                         exit
+                    }
+                    t = -1
+                    u = index($0, "*/")
+               }
+               # substr expression will be "" if */
+               # occurred at end of line
+               $0 = tmp substr($0, t + u + 3)
+          }
+          print $0
+     }'
+
+   This `awk' program deletes all C-style comments, `/* ...  */', from
+the input.  By replacing the `print $0' with other statements, you
+could perform more complicated processing on the decommented input,
+like searching for matches of a regular expression.  This program has a
+subtle problem--it does not work if one comment ends and another begins
+on the same line.
+
+   This form of the `getline' command sets `NF' (the number of fields;
+*note Examining Fields: Fields.), `NR' (the number of records read so
+far; *note How Input is Split into Records: Records.), `FNR' (the
+number of records read from this input file), and the value of `$0'.
+
+   *Note:* the new value of `$0' is used in testing the patterns of any
+subsequent rules.  The original value of `$0' that triggered the rule
+which executed `getline' is lost (d.c.).  By contrast, the `next'
+statement reads a new record but immediately begins processing it
+normally, starting with the first rule in the program.  *Note The
+`next' Statement: Next Statement.
+
+
+File: gawk.info,  Node: Getline/Variable,  Next: Getline/File,  Prev: Plain Getline,  Up: Getline
+
+Using `getline' Into a Variable
+-------------------------------
+
+   You can use `getline VAR' to read the next record from `awk''s input
+into the variable VAR.  No other processing is done.
+
+   For example, suppose the next line is a comment, or a special string,
+and you want to read it, without triggering any rules.  This form of
+`getline' allows you to read that line and store it in a variable so
+that the main read-a-line-and-check-each-rule loop of `awk' never sees
+it.
+
+   The following example swaps every two lines of input.  For example,
+given:
+
+     wan
+     tew
+     free
+     phore
+
+it outputs:
+
+     tew
+     wan
+     phore
+     free
+
+Here's the program:
+
+     awk '{
+          if ((getline tmp) > 0) {
+               print tmp
+               print $0
+          } else
+               print $0
+     }'
+
+   The `getline' command used in this way sets only the variables `NR'
+and `FNR' (and of course, VAR).  The record is not split into fields,
+so the values of the fields (including `$0') and the value of `NF' do
+not change.
+
+
+File: gawk.info,  Node: Getline/File,  Next: Getline/Variable/File,  Prev: Getline/Variable,  Up: Getline
+
+Using `getline' from a File
+---------------------------
+
+   Use `getline < FILE' to read the next record from the file FILE.
+Here FILE is a string-valued expression that specifies the file name.
+`< FILE' is called a "redirection" since it directs input to come from
+a different place.
+
+   For example, the following program reads its input record from the
+file `secondary.input' when it encounters a first field with a value
+equal to 10 in the current input file.
+
+     awk '{
+         if ($1 == 10) {
+              getline < "secondary.input"
+              print
+         } else
+              print
+     }'
+
+   Since the main input stream is not used, the values of `NR' and
+`FNR' are not changed.  But the record read is split into fields in the
+normal manner, so the values of `$0' and other fields are changed.  So
+is the value of `NF'.
+
+   According to POSIX, `getline < EXPRESSION' is ambiguous if
+EXPRESSION contains unparenthesized operators other than `$'; for
+example, `getline < dir "/" file' is ambiguous because the
+concatenation operator is not parenthesized, and you should write it as
+`getline < (dir "/" file)' if you want your program to be portable to
+other `awk' implementations.
+
+
+File: gawk.info,  Node: Getline/Variable/File,  Next: Getline/Pipe,  Prev: Getline/File,  Up: Getline
+
+Using `getline' Into a Variable from a File
+-------------------------------------------
+
+   Use `getline VAR < FILE' to read input the file FILE and put it in
+the variable VAR.  As above, FILE is a string-valued expression that
+specifies the file from which to read.
+
+   In this version of `getline', none of the built-in variables are
+changed, and the record is not split into fields.  The only variable
+changed is VAR.
+
+   According to POSIX, `getline VAR < EXPRESSION' is ambiguous if
+EXPRESSION contains unparenthesized operators other than `$'; for
+example, `getline < dir "/" file' is ambiguous because the
+concatenation operator is not parenthesized, and you should write it as
+`getline < (dir "/" file)' if you want your program to be portable to
+other `awk' implementations.
+
+   For example, the following program copies all the input files to the
+output, except for records that say `@include FILENAME'.  Such a record
+is replaced by the contents of the file FILENAME.
+
+     awk '{
+          if (NF == 2 && $1 == "@include") {
+               while ((getline line < $2) > 0)
+                    print line
+               close($2)
+          } else
+               print
+     }'
+
+   Note here how the name of the extra input file is not built into the
+program; it is taken directly from the data, from the second field on
+the `@include' line.
+
+   The `close' function is called to ensure that if two identical
+`@include' lines appear in the input, the entire specified file is
+included twice.  *Note Closing Input and Output Files and Pipes: Close
+Files And Pipes.
+
+   One deficiency of this program is that it does not process nested
+`@include' statements (`@include' statements in included files) the way
+a true macro preprocessor would.  *Note An Easy Way to Use Library
+Functions: Igawk Program, for a program that does handle nested
+`@include' statements.
+
+
+File: gawk.info,  Node: Getline/Pipe,  Next: Getline/Variable/Pipe,  Prev: Getline/Variable/File,  Up: Getline
+
+Using `getline' from a Pipe
+---------------------------
+
+   You can pipe the output of a command into `getline', using `COMMAND
+| getline'.  In this case, the string COMMAND is run as a shell command
+and its output is piped into `awk' to be used as input.  This form of
+`getline' reads one record at a time from the pipe.
+
+   For example, the following program copies its input to its output,
+except for lines that begin with `@execute', which are replaced by the
+output produced by running the rest of the line as a shell command:
+
+     awk '{
+          if ($1 == "@execute") {
+               tmp = substr($0, 10)
+               while ((tmp | getline) > 0)
+                    print
+               close(tmp)
+          } else
+               print
+     }'
+
+The `close' function is called to ensure that if two identical
+`@execute' lines appear in the input, the command is run for each one.
+*Note Closing Input and Output Files and Pipes: Close Files And Pipes.
+
+   Given the input:
+
+     foo
+     bar
+     baz
+     @execute who
+     bletch
+
+the program might produce:
+
+     foo
+     bar
+     baz
+     arnold     ttyv0   Jul 13 14:22
+     miriam     ttyp0   Jul 13 14:23     (murphy:0)
+     bill       ttyp1   Jul 13 14:23     (murphy:0)
+     bletch
+
+Notice that this program ran the command `who' and printed the result.
+(If you try this program yourself, you will of course get different
+results, showing you who is logged in on your system.)
+
+   This variation of `getline' splits the record into fields, sets the
+value of `NF' and recomputes the value of `$0'.  The values of `NR' and
+`FNR' are not changed.
+
+   According to POSIX, `EXPRESSION | getline' is ambiguous if
+EXPRESSION contains unparenthesized operators other than `$'; for
+example, `"echo " "date" | getline' is ambiguous because the
+concatenation operator is not parenthesized, and you should write it as
+`("echo " "date") | getline' if you want your program to be portable to
+other `awk' implementations.
+
+
+File: gawk.info,  Node: Getline/Variable/Pipe,  Next: Getline Summary,  Prev: Getline/Pipe,  Up: Getline
+
+Using `getline' Into a Variable from a Pipe
+-------------------------------------------
+
+   When you use `COMMAND | getline VAR', the output of the command
+COMMAND is sent through a pipe to `getline' and into the variable VAR.
+For example, the following program reads the current date and time into
+the variable `current_time', using the `date' utility, and then prints
+it.
+
+     awk 'BEGIN {
+          "date" | getline current_time
+          close("date")
+          print "Report printed on " current_time
+     }'
+
+   In this version of `getline', none of the built-in variables are
+changed, and the record is not split into fields.
+
+   According to POSIX, `EXPRESSION | getline VAR' is ambiguous if
+EXPRESSION contains unparenthesized operators other than `$'; for
+example, `"echo " "date" | getline VAR' is ambiguous because the
+concatenation operator is not parenthesized, and you should write it as
+`("echo " "date") | getline VAR' if you want your program to be
+portable to other `awk' implementations.
+
+
+File: gawk.info,  Node: Getline Summary,  Prev: Getline/Variable/Pipe,  Up: Getline
+
+Summary of `getline' Variants
+-----------------------------
+
+   With all the forms of `getline', even though `$0' and `NF', may be
+updated, the record will not be tested against all the patterns in the
+`awk' program, in the way that would happen if the record were read
+normally by the main processing loop of `awk'.  However the new record
+is tested against any subsequent rules.
+
+   Many `awk' implementations limit the number of pipelines an `awk'
+program may have open to just one!  In `gawk', there is no such limit.
+You can open as many pipelines as the underlying operating system will
+permit.
+
+   An interesting side-effect occurs if you use `getline' (without a
+redirection) inside a `BEGIN' rule. Since an unredirected `getline'
+reads from the command line data files, the first `getline' command
+causes `awk' to set the value of `FILENAME'. Normally, `FILENAME' does
+not have a value inside `BEGIN' rules, since you have not yet started
+to process the command line data files (d.c.).  (*Note The `BEGIN' and
+`END' Special Patterns: BEGIN/END, also *note Built-in Variables that
+Convey Information: Auto-set..)
+
+   The following table summarizes the six variants of `getline',
+listing which built-in variables are set by each one.
+
+`getline'
+     sets `$0', `NF', `FNR', and `NR'.
+
+`getline VAR'
+     sets VAR, `FNR', and `NR'.
+
+`getline < FILE'
+     sets `$0', and `NF'.
+
+`getline VAR < FILE'
+     sets VAR.
+
+`COMMAND | getline'
+     sets `$0', and `NF'.
+
+`COMMAND | getline VAR'
+     sets VAR.
+
+
+File: gawk.info,  Node: Printing,  Next: Expressions,  Prev: Reading Files,  Up: Top
+
+Printing Output
+***************
+
+   One of the most common actions is to "print", or output, some or all
+of the input.  You use the `print' statement for simple output.  You
+use the `printf' statement for fancier formatting.  Both are described
+in this chapter.
+
+* Menu:
+
+* Print::                       The `print' statement.
+* Print Examples::              Simple examples of `print' statements.
+* Output Separators::           The output separators and how to change them.
+* OFMT::                        Controlling Numeric Output With `print'.
+* Printf::                      The `printf' statement.
+* Redirection::                 How to redirect output to multiple files and
+                                pipes.
+* Special Files::               File name interpretation in `gawk'.
+                                `gawk' allows access to inherited file
+                                descriptors.
+* Close Files And Pipes::       Closing Input and Output Files and Pipes.
+
+
+File: gawk.info,  Node: Print,  Next: Print Examples,  Prev: Printing,  Up: Printing
+
+The `print' Statement
+=====================
+
+   The `print' statement does output with simple, standardized
+formatting.  You specify only the strings or numbers to be printed, in a
+list separated by commas.  They are output, separated by single spaces,
+followed by a newline.  The statement looks like this:
+
+     print ITEM1, ITEM2, ...
+
+The entire list of items may optionally be enclosed in parentheses.  The
+parentheses are necessary if any of the item expressions uses the `>'
+relational operator; otherwise it could be confused with a redirection
+(*note Redirecting Output of `print' and `printf': Redirection.).
+
+   The items to be printed can be constant strings or numbers, fields
+of the current record (such as `$1'), variables, or any `awk'
+expressions.  Numeric values are converted to strings, and then printed.
+
+   The `print' statement is completely general for computing _what_
+values to print. However, with two exceptions, you cannot specify _how_
+to print them--how many columns, whether to use exponential notation or
+not, and so on.  (For the exceptions, *note Output Separators::, and
+*Note Controlling Numeric Output with `print': OFMT.)  For that, you
+need the `printf' statement (*note Using `printf' Statements for
+Fancier Printing: Printf.).
+
+   The simple statement `print' with no items is equivalent to `print
+$0': it prints the entire current record.  To print a blank line, use
+`print ""', where `""' is the empty string.
+
+   To print a fixed piece of text, use a string constant such as
+`"Don't Panic"' as one item.  If you forget to use the double-quote
+characters, your text will be taken as an `awk' expression, and you
+will probably get an error.  Keep in mind that a space is printed
+between any two items.
+
+   Each `print' statement makes at least one line of output.  But it
+isn't limited to one line.  If an item value is a string that contains a
+newline, the newline is output along with the rest of the string.  A
+single `print' can make any number of lines this way.
+
+
+File: gawk.info,  Node: Print Examples,  Next: Output Separators,  Prev: Print,  Up: Printing
+
+Examples of `print' Statements
+==============================
+
+   Here is an example of printing a string that contains embedded
+newlines (the `\n' is an escape sequence, used to represent the newline
+character; see *Note Escape Sequences::):
+
+     $ awk 'BEGIN { print "line one\nline two\nline three" }'
+     -| line one
+     -| line two
+     -| line three
+
+   Here is an example that prints the first two fields of each input
+record, with a space between them:
+
+     $ awk '{ print $1, $2 }' inventory-shipped
+     -| Jan 13
+     -| Feb 15
+     -| Mar 15
+     ...
+
+   A common mistake in using the `print' statement is to omit the comma
+between two items.  This often has the effect of making the items run
+together in the output, with no space.  The reason for this is that
+juxtaposing two string expressions in `awk' means to concatenate them.
+Here is the same program, without the comma:
+
+     $ awk '{ print $1 $2 }' inventory-shipped
+     -| Jan13
+     -| Feb15
+     -| Mar15
+     ...
+
+   To someone unfamiliar with the file `inventory-shipped', neither
+example's output makes much sense.  A heading line at the beginning
+would make it clearer.  Let's add some headings to our table of months
+(`$1') and green crates shipped (`$2').  We do this using the `BEGIN'
+pattern (*note The `BEGIN' and `END' Special Patterns: BEGIN/END.)  to
+force the headings to be printed only once:
+
+     awk 'BEGIN {  print "Month Crates"
+                   print "----- ------" }
+                {  print $1, $2 }' inventory-shipped
+
+Did you already guess what happens? When run, the program prints the
+following:
+
+     Month Crates
+     ----- ------
+     Jan 13
+     Feb 15
+     Mar 15
+     ...
+
+The headings and the table data don't line up!  We can fix this by
+printing some spaces between the two fields:
+
+     awk 'BEGIN { print "Month Crates"
+                  print "----- ------" }
+                { print $1, "     ", $2 }' inventory-shipped
+
+   You can imagine that this way of lining up columns can get pretty
+complicated when you have many columns to fix.  Counting spaces for two
+or three columns can be simple, but more than this and you can get lost
+quite easily.  This is why the `printf' statement was created (*note
+Using `printf' Statements for Fancier Printing: Printf.); one of its
+specialties is lining up columns of data.
+
+   As a side point, you can continue either a `print' or `printf'
+statement simply by putting a newline after any comma (*note `awk'
+Statements Versus Lines: Statements/Lines.).
+
+
+File: gawk.info,  Node: Output Separators,  Next: OFMT,  Prev: Print Examples,  Up: Printing
+
+Output Separators
+=================
+
+   As mentioned previously, a `print' statement contains a list of
+items, separated by commas.  In the output, the items are normally
+separated by single spaces.  This need not be the case; a single space
+is only the default.  You can specify any string of characters to use
+as the "output field separator" by setting the built-in variable `OFS'.
+The initial value of this variable is the string `" "', that is, a
+single space.
+
+   The output from an entire `print' statement is called an "output
+record".  Each `print' statement outputs one output record and then
+outputs a string called the "output record separator".  The built-in
+variable `ORS' specifies this string.  The initial value of `ORS' is
+the string `"\n"', i.e. a newline character; thus, normally each
+`print' statement makes a separate line.
+
+   You can change how output fields and records are separated by
+assigning new values to the variables `OFS' and/or `ORS'.  The usual
+place to do this is in the `BEGIN' rule (*note The `BEGIN' and `END'
+Special Patterns: BEGIN/END.), so that it happens before any input is
+processed.  You may also do this with assignments on the command line,
+before the names of your input files, or using the `-v' command line
+option (*note Command Line Options: Options.).
+
+   The following example prints the first and second fields of each
+input record separated by a semicolon, with a blank line added after
+each line:
+
+     $ awk 'BEGIN { OFS = ";"; ORS = "\n\n" }
+     >            { print $1, $2 }' BBS-list
+     -| aardvark;555-5553
+     -|
+     -| alpo-net;555-3412
+     -|
+     -| barfly;555-7685
+     ...
+
+   If the value of `ORS' does not contain a newline, all your output
+will be run together on a single line, unless you output newlines some
+other way.
+
+
+File: gawk.info,  Node: OFMT,  Next: Printf,  Prev: Output Separators,  Up: Printing
+
+Controlling Numeric Output with `print'
+=======================================
+
+   When you use the `print' statement to print numeric values, `awk'
+internally converts the number to a string of characters, and prints
+that string.  `awk' uses the `sprintf' function to do this conversion
+(*note Built-in Functions for String Manipulation: String Functions.).
+For now, it suffices to say that the `sprintf' function accepts a
+"format specification" that tells it how to format numbers (or
+strings), and that there are a number of different ways in which
+numbers can be formatted.  The different format specifications are
+discussed more fully in *Note Format-Control Letters: Control Letters.
+
+   The built-in variable `OFMT' contains the default format
+specification that `print' uses with `sprintf' when it wants to convert
+a number to a string for printing.  The default value of `OFMT' is
+`"%.6g"'.  By supplying different format specifications as the value of
+`OFMT', you can change how `print' will print your numbers.  As a brief
+example:
+
+     $ awk 'BEGIN {
+     >   OFMT = "%.0f"  # print numbers as integers (rounds)
+     >   print 17.23 }'
+     -| 17
+
+According to the POSIX standard, `awk''s behavior will be undefined if
+`OFMT' contains anything but a floating point conversion specification
+(d.c.).
+
+
+File: gawk.info,  Node: Printf,  Next: Redirection,  Prev: OFMT,  Up: Printing
+
+Using `printf' Statements for Fancier Printing
+==============================================
+
+   If you want more precise control over the output format than `print'
+gives you, use `printf'.  With `printf' you can specify the width to
+use for each item, and you can specify various formatting choices for
+numbers (such as what radix to use, whether to print an exponent,
+whether to print a sign, and how many digits to print after the decimal
+point).  You do this by supplying a string, called the "format string",
+which controls how and where to print the other arguments.
+
+* Menu:
+
+* Basic Printf::                Syntax of the `printf' statement.
+* Control Letters::             Format-control letters.
+* Format Modifiers::            Format-specification modifiers.
+* Printf Examples::             Several examples.
+
+
+File: gawk.info,  Node: Basic Printf,  Next: Control Letters,  Prev: Printf,  Up: Printf
+
+Introduction to the `printf' Statement
+--------------------------------------
+
+   The `printf' statement looks like this:
+
+     printf FORMAT, ITEM1, ITEM2, ...
+
+The entire list of arguments may optionally be enclosed in parentheses.
+The parentheses are necessary if any of the item expressions use the
+`>' relational operator; otherwise it could be confused with a
+redirection (*note Redirecting Output of `print' and `printf':
+Redirection.).
+
+   The difference between `printf' and `print' is the FORMAT argument.
+This is an expression whose value is taken as a string; it specifies
+how to output each of the other arguments.  It is called the "format
+string".
+
+   The format string is very similar to that in the ANSI C library
+function `printf'.  Most of FORMAT is text to be output verbatim.
+Scattered among this text are "format specifiers", one per item.  Each
+format specifier says to output the next item in the argument list at
+that place in the format.
+
+   The `printf' statement does not automatically append a newline to its
+output.  It outputs only what the format string specifies.  So if you
+want a newline, you must include one in the format string.  The output
+separator variables `OFS' and `ORS' have no effect on `printf'
+statements. For example:
+
+     BEGIN {
+        ORS = "\nOUCH!\n"; OFS = "!"
+        msg = "Don't Panic!"; printf "%s\n", msg
+     }
+
+   This program still prints the familiar `Don't Panic!' message.
+
+
+File: gawk.info,  Node: Control Letters,  Next: Format Modifiers,  Prev: Basic Printf,  Up: Printf
+
+Format-Control Letters
+----------------------
+
+   A format specifier starts with the character `%' and ends with a
+"format-control letter"; it tells the `printf' statement how to output
+one item.  (If you actually want to output a `%', write `%%'.)  The
+format-control letter specifies what kind of value to print.  The rest
+of the format specifier is made up of optional "modifiers" which are
+parameters to use, such as the field width.
+
+   Here is a list of the format-control letters:
+
+`c'
+     This prints a number as an ASCII character.  Thus, `printf "%c",
+     65' outputs the letter `A'.  The output for a string value is the
+     first character of the string.
+
+`d'
+`i'
+     These are equivalent. They both print a decimal integer.  The `%i'
+     specification is for compatibility with ANSI C.
+
+`e'
+`E'
+     This prints a number in scientific (exponential) notation.  For
+     example,
+
+          printf "%4.3e\n", 1950
+
+     prints `1.950e+03', with a total of four significant figures of
+     which three follow the decimal point.  The `4.3' are modifiers,
+     discussed below. `%E' uses `E' instead of `e' in the output.
+
+`f'
+     This prints a number in floating point notation.  For example,
+
+          printf "%4.3f", 1950
+
+     prints `1950.000', with a total of four significant figures of
+     which three follow the decimal point.  The `4.3' are modifiers,
+     discussed below.
+
+`g'
+`G'
+     This prints a number in either scientific notation or floating
+     point notation, whichever uses fewer characters. If the result is
+     printed in scientific notation, `%G' uses `E' instead of `e'.
+
+`o'
+     This prints an unsigned octal integer.  (In octal, or base-eight
+     notation, the digits run from `0' to `7'; the decimal number eight
+     is represented as `10' in octal.)
+
+`s'
+     This prints a string.
+
+`x'
+`X'
+     This prints an unsigned hexadecimal integer.  (In hexadecimal, or
+     base-16 notation, the digits are `0' through `9' and `a' through
+     `f'.  The hexadecimal digit `f' represents the decimal number 15.)
+     `%X' uses the letters `A' through `F' instead of `a' through `f'.
+
+`%'
+     This isn't really a format-control letter, but it does have a
+     meaning when used after a `%': the sequence `%%' outputs one `%'.
+     It does not consume an argument, and it ignores any modifiers.
+
+   When using the integer format-control letters for values that are
+outside the range of a C `long' integer, `gawk' will switch to the `%g'
+format specifier. Other versions of `awk' may print invalid values, or
+do something else entirely (d.c.).
+
+
+File: gawk.info,  Node: Format Modifiers,  Next: Printf Examples,  Prev: Control Letters,  Up: Printf
+
+Modifiers for `printf' Formats
+------------------------------
+
+   A format specification can also include "modifiers" that can control
+how much of the item's value is printed and how much space it gets.  The
+modifiers come between the `%' and the format-control letter.  In the
+examples below, we use the bullet symbol "*" to represent spaces in the
+output. Here are the possible modifiers, in the order in which they may
+appear:
+
+`-'
+     The minus sign, used before the width modifier (see below), says
+     to left-justify the argument within its specified width.  Normally
+     the argument is printed right-justified in the specified width.
+     Thus,
+
+          printf "%-4s", "foo"
+
+     prints `foo*'.
+
+`SPACE'
+     For numeric conversions, prefix positive values with a space, and
+     negative values with a minus sign.
+
+`+'
+     The plus sign, used before the width modifier (see below), says to
+     always supply a sign for numeric conversions, even if the data to
+     be formatted is positive. The `+' overrides the space modifier.
+
+`#'
+     Use an "alternate form" for certain control letters.  For `%o',
+     supply a leading zero.  For `%x', and `%X', supply a leading `0x'
+     or `0X' for a non-zero result.  For `%e', `%E', and `%f', the
+     result will always contain a decimal point.  For `%g', and `%G',
+     trailing zeros are not removed from the result.
+
+`0'
+     A leading `0' (zero) acts as a flag, that indicates output should
+     be padded with zeros instead of spaces.  This applies even to
+     non-numeric output formats (d.c.).  This flag only has an effect
+     when the field width is wider than the value to be printed.
+
+`WIDTH'
+     This is a number specifying the desired minimum width of a field.
+     Inserting any number between the `%' sign and the format control
+     character forces the field to be expanded to this width.  The
+     default way to do this is to pad with spaces on the left.  For
+     example,
+
+          printf "%4s", "foo"
+
+     prints `*foo'.
+
+     The value of WIDTH is a minimum width, not a maximum.  If the item
+     value requires more than WIDTH characters, it can be as wide as
+     necessary.  Thus,
+
+          printf "%4s", "foobar"
+
+     prints `foobar'.
+
+     Preceding the WIDTH with a minus sign causes the output to be
+     padded with spaces on the right, instead of on the left.
+
+`.PREC'
+     This is a number that specifies the precision to use when printing.
+     For the `e', `E', and `f' formats, this specifies the number of
+     digits you want printed to the right of the decimal point.  For
+     the `g', and `G' formats, it specifies the maximum number of
+     significant digits.  For the `d', `o', `i', `u', `x', and `X'
+     formats, it specifies the minimum number of digits to print.  For
+     a string, it specifies the maximum number of characters from the
+     string that should be printed.  Thus,
+
+          printf "%.4s", "foobar"
+
+     prints `foob'.
+
+   The C library `printf''s dynamic WIDTH and PREC capability (for
+example, `"%*.*s"') is supported.  Instead of supplying explicit WIDTH
+and/or PREC values in the format string, you pass them in the argument
+list.  For example:
+
+     w = 5
+     p = 3
+     s = "abcdefg"
+     printf "%*.*s\n", w, p, s
+
+is exactly equivalent to
+
+     s = "abcdefg"
+     printf "%5.3s\n", s
+
+Both programs output `**abc'.
+
+   Earlier versions of `awk' did not support this capability.  If you
+must use such a version, you may simulate this feature by using
+concatenation to build up the format string, like so:
+
+     w = 5
+     p = 3
+     s = "abcdefg"
+     printf "%" w "." p "s\n", s
+
+This is not particularly easy to read, but it does work.
+
+   C programmers may be used to supplying additional `l' and `h' flags
+in `printf' format strings. These are not valid in `awk'.  Most `awk'
+implementations silently ignore these flags.  If `--lint' is provided
+on the command line (*note Command Line Options: Options.), `gawk' will
+warn about their use. If `--posix' is supplied, their use is a fatal
+error.
+
+
+File: gawk.info,  Node: Printf Examples,  Prev: Format Modifiers,  Up: Printf
+
+Examples Using `printf'
+-----------------------
+
+   Here is how to use `printf' to make an aligned table:
+
+     awk '{ printf "%-10s %s\n", $1, $2 }' BBS-list
+
+prints the names of bulletin boards (`$1') of the file `BBS-list' as a
+string of 10 characters, left justified.  It also prints the phone
+numbers (`$2') afterward on the line.  This produces an aligned
+two-column table of names and phone numbers:
+
+     $ awk '{ printf "%-10s %s\n", $1, $2 }' BBS-list
+     -| aardvark   555-5553
+     -| alpo-net   555-3412
+     -| barfly     555-7685
+     -| bites      555-1675
+     -| camelot    555-0542
+     -| core       555-2912
+     -| fooey      555-1234
+     -| foot       555-6699
+     -| macfoo     555-6480
+     -| sdace      555-3430
+     -| sabafoo    555-2127
+
+   Did you notice that we did not specify that the phone numbers be
+printed as numbers?  They had to be printed as strings because the
+numbers are separated by a dash.  If we had tried to print the phone
+numbers as numbers, all we would have gotten would have been the first
+three digits, `555'.  This would have been pretty confusing.
+
+   We did not specify a width for the phone numbers because they are the
+last things on their lines.  We don't need to put spaces after them.
+
+   We could make our table look even nicer by adding headings to the
+tops of the columns.  To do this, we use the `BEGIN' pattern (*note The
+`BEGIN' and `END' Special Patterns: BEGIN/END.)  to force the header to
+be printed only once, at the beginning of the `awk' program:
+
+     awk 'BEGIN { print "Name      Number"
+                  print "----      ------" }
+          { printf "%-10s %s\n", $1, $2 }' BBS-list
+
+   Did you notice that we mixed `print' and `printf' statements in the
+above example?  We could have used just `printf' statements to get the
+same results:
+
+     awk 'BEGIN { printf "%-10s %s\n", "Name", "Number"
+                  printf "%-10s %s\n", "----", "------" }
+          { printf "%-10s %s\n", $1, $2 }' BBS-list
+
+By printing each column heading with the same format specification used
+for the elements of the column, we have made sure that the headings are
+aligned just like the columns.
+
+   The fact that the same format specification is used three times can
+be emphasized by storing it in a variable, like this:
+
+     awk 'BEGIN { format = "%-10s %s\n"
+                  printf format, "Name", "Number"
+                  printf format, "----", "------" }
+          { printf format, $1, $2 }' BBS-list
+
+   See if you can use the `printf' statement to line up the headings and
+table data for our `inventory-shipped' example covered earlier in the
+section on the `print' statement (*note The `print' Statement: Print.).
+
+
+File: gawk.info,  Node: Redirection,  Next: Special Files,  Prev: Printf,  Up: Printing
+
+Redirecting Output of `print' and `printf'
+==========================================
+
+   So far we have been dealing only with output that prints to the
+standard output, usually your terminal.  Both `print' and `printf' can
+also send their output to other places.  This is called "redirection".
+
+   A redirection appears after the `print' or `printf' statement.
+Redirections in `awk' are written just like redirections in shell
+commands, except that they are written inside the `awk' program.
+
+   There are three forms of output redirection: output to a file,
+output appended to a file, and output through a pipe to another command.
+They are all shown for the `print' statement, but they work identically
+for `printf' also.
+
+`print ITEMS > OUTPUT-FILE'
+     This type of redirection prints the items into the output file
+     OUTPUT-FILE.  The file name OUTPUT-FILE can be any expression.
+     Its value is changed to a string and then used as a file name
+     (*note Expressions::).
+
+     When this type of redirection is used, the OUTPUT-FILE is erased
+     before the first output is written to it.  Subsequent writes to
+     the same OUTPUT-FILE do not erase OUTPUT-FILE, but append to it.
+     If OUTPUT-FILE does not exist, then it is created.
+
+     For example, here is how an `awk' program can write a list of BBS
+     names to a file `name-list' and a list of phone numbers to a file
+     `phone-list'.  Each output file contains one name or number per
+     line.
+
+          $ awk '{ print $2 > "phone-list"
+          >        print $1 > "name-list" }' BBS-list
+          $ cat phone-list
+          -| 555-5553
+          -| 555-3412
+          ...
+          $ cat name-list
+          -| aardvark
+          -| alpo-net
+          ...
+
+`print ITEMS >> OUTPUT-FILE'
+     This type of redirection prints the items into the pre-existing
+     output file OUTPUT-FILE.  The difference between this and the
+     single-`>' redirection is that the old contents (if any) of
+     OUTPUT-FILE are not erased.  Instead, the `awk' output is appended
+     to the file.  If OUTPUT-FILE does not exist, then it is created.
+
+`print ITEMS | COMMAND'
+     It is also possible to send output to another program through a
+     pipe instead of into a file.   This type of redirection opens a
+     pipe to COMMAND and writes the values of ITEMS through this pipe,
+     to another process created to execute COMMAND.
+
+     The redirection argument COMMAND is actually an `awk' expression.
+     Its value is converted to a string, whose contents give the shell
+     command to be run.
+
+     For example, this produces two files, one unsorted list of BBS
+     names and one list sorted in reverse alphabetical order:
+
+          awk '{ print $1 > "names.unsorted"
+                 command = "sort -r > names.sorted"
+                 print $1 | command }' BBS-list
+
+     Here the unsorted list is written with an ordinary redirection
+     while the sorted list is written by piping through the `sort'
+     utility.
+
+     This example uses redirection to mail a message to a mailing list
+     `bug-system'.  This might be useful when trouble is encountered in
+     an `awk' script run periodically for system maintenance.
+
+          report = "mail bug-system"
+          print "Awk script failed:", $0 | report
+          m = ("at record number " FNR " of " FILENAME)
+          print m | report
+          close(report)
+
+     The message is built using string concatenation and saved in the
+     variable `m'.  It is then sent down the pipeline to the `mail'
+     program.
+
+     We call the `close' function here because it's a good idea to close
+     the pipe as soon as all the intended output has been sent to it.
+     *Note Closing Input and Output Files and Pipes: Close Files And
+     Pipes, for more information on this.  This example also
+     illustrates the use of a variable to represent a FILE or COMMAND:
+     it is not necessary to always use a string constant.  Using a
+     variable is generally a good idea, since `awk' requires you to
+     spell the string value identically every time.
+
+   Redirecting output using `>', `>>', or `|' asks the system to open a
+file or pipe only if the particular FILE or COMMAND you've specified
+has not already been written to by your program, or if it has been
+closed since it was last written to.
+
+   Many `awk' implementations limit the number of pipelines an `awk'
+program may have open to just one!  In `gawk', there is no such limit.
+You can open as many pipelines as the underlying operating system will
+permit.
+
+
+File: gawk.info,  Node: Special Files,  Next: Close Files And Pipes,  Prev: Redirection,  Up: Printing
+
+Special File Names in `gawk'
+============================
+
+   Running programs conventionally have three input and output streams
+already available to them for reading and writing.  These are known as
+the "standard input", "standard output", and "standard error output".
+These streams are, by default, connected to your terminal, but they are
+often redirected with the shell, via the `<', `<<', `>', `>>', `>&' and
+`|' operators.  Standard error is typically used for writing error
+messages; the reason we have two separate streams, standard output and
+standard error, is so that they can be redirected separately.
+
+   In other implementations of `awk', the only way to write an error
+message to standard error in an `awk' program is as follows:
+
+     print "Serious error detected!" | "cat 1>&2"
+
+This works by opening a pipeline to a shell command which can access the
+standard error stream which it inherits from the `awk' process.  This
+is far from elegant, and is also inefficient, since it requires a
+separate process.  So people writing `awk' programs often neglect to do
+this.  Instead, they send the error messages to the terminal, like this:
+
+     print "Serious error detected!" > "/dev/tty"
+
+This usually has the same effect, but not always: although the standard
+error stream is usually the terminal, it can be redirected, and when
+that happens, writing to the terminal is not correct.  In fact, if
+`awk' is run from a background job, it may not have a terminal at all.
+Then opening `/dev/tty' will fail.
+
+   `gawk' provides special file names for accessing the three standard
+streams.  When you redirect input or output in `gawk', if the file name
+matches one of these special names, then `gawk' directly uses the
+stream it stands for.
+
+`/dev/stdin'
+     The standard input (file descriptor 0).
+
+`/dev/stdout'
+     The standard output (file descriptor 1).
+
+`/dev/stderr'
+     The standard error output (file descriptor 2).
+
+`/dev/fd/N'
+     The file associated with file descriptor N.  Such a file must have
+     been opened by the program initiating the `awk' execution
+     (typically the shell).  Unless you take special pains in the shell
+     from which you invoke `gawk', only descriptors 0, 1 and 2 are
+     available.
+
+   The file names `/dev/stdin', `/dev/stdout', and `/dev/stderr' are
+aliases for `/dev/fd/0', `/dev/fd/1', and `/dev/fd/2', respectively,
+but they are more self-explanatory.
+
+   The proper way to write an error message in a `gawk' program is to
+use `/dev/stderr', like this:
+
+     print "Serious error detected!" > "/dev/stderr"
+
+   `gawk' also provides special file names that give access to
+information about the running `gawk' process.  Each of these "files"
+provides a single record of information.  To read them more than once,
+you must first close them with the `close' function (*note Closing
+Input and Output Files and Pipes: Close Files And Pipes.).  The
+filenames are:
+
+`/dev/pid'
+     Reading this file returns the process ID of the current process,
+     in decimal, terminated with a newline.
+
+`/dev/ppid'
+     Reading this file returns the parent process ID of the current
+     process, in decimal, terminated with a newline.
+
+`/dev/pgrpid'
+     Reading this file returns the process group ID of the current
+     process, in decimal, terminated with a newline.
+
+`/dev/user'
+     Reading this file returns a single record terminated with a
+     newline.  The fields are separated with spaces.  The fields
+     represent the following information:
+
+    `$1'
+          The return value of the `getuid' system call (the real user
+          ID number).
+
+    `$2'
+          The return value of the `geteuid' system call (the effective
+          user ID number).
+
+    `$3'
+          The return value of the `getgid' system call (the real group
+          ID number).
+
+    `$4'
+          The return value of the `getegid' system call (the effective
+          group ID number).
+
+     If there are any additional fields, they are the group IDs
+     returned by `getgroups' system call.  (Multiple groups may not be
+     supported on all systems.)
+
+   These special file names may be used on the command line as data
+files, as well as for I/O redirections within an `awk' program.  They
+may not be used as source files with the `-f' option.
+
+   Recognition of these special file names is disabled if `gawk' is in
+compatibility mode (*note Command Line Options: Options.).
+
+   *Caution*:  Unless your system actually has a `/dev/fd' directory
+(or any of the other above listed special files), the interpretation of
+these file names is done by `gawk' itself.  For example, using
+`/dev/fd/4' for output will actually write on file descriptor 4, and
+not on a new file descriptor that was `dup''ed from file descriptor 4.
+Most of the time this does not matter; however, it is important to
+_not_ close any of the files related to file descriptors 0, 1, and 2.
+If you do close one of these files, unpredictable behavior will result.
+
+   The special files that provide process-related information may
+disappear in a future version of `gawk'.  *Note Probable Future
+Extensions: Future Extensions.
+
+
+File: gawk.info,  Node: Close Files And Pipes,  Prev: Special Files,  Up: Printing
+
+Closing Input and Output Files and Pipes
+========================================
+
+   If the same file name or the same shell command is used with
+`getline' (*note Explicit Input with `getline': Getline.)  more than
+once during the execution of an `awk' program, the file is opened (or
+the command is executed) only the first time.  At that time, the first
+record of input is read from that file or command.  The next time the
+same file or command is used in `getline', another record is read from
+it, and so on.
+
+   Similarly, when a file or pipe is opened for output, the file name
+or command associated with it is remembered by `awk' and subsequent
+writes to the same file or command are appended to the previous writes.
+The file or pipe stays open until `awk' exits.
+
+   This implies that if you want to start reading the same file again
+from the beginning, or if you want to rerun a shell command (rather than
+reading more output from the command), you must take special steps.
+What you must do is use the `close' function, as follows:
+
+     close(FILENAME)
+
+or
+
+     close(COMMAND)
+
+   The argument FILENAME or COMMAND can be any expression.  Its value
+must _exactly_ match the string that was used to open the file or start
+the command (spaces and other "irrelevant" characters included). For
+example, if you open a pipe with this:
+
+     "sort -r names" | getline foo
+
+then you must close it with this:
+
+     close("sort -r names")
+
+   Once this function call is executed, the next `getline' from that
+file or command, or the next `print' or `printf' to that file or
+command, will reopen the file or rerun the command.
+
+   Because the expression that you use to close a file or pipeline must
+exactly match the expression used to open the file or run the command,
+it is good practice to use a variable to store the file name or command.
+The previous example would become
+
+     sortcom = "sort -r names"
+     sortcom | getline foo
+     ...
+     close(sortcom)
+
+This helps avoid hard-to-find typographical errors in your `awk'
+programs.
+
+   Here are some reasons why you might need to close an output file:
+
+   * To write a file and read it back later on in the same `awk'
+     program.  Close the file when you are finished writing it; then
+     you can start reading it with `getline'.
+
+   * To write numerous files, successively, in the same `awk' program.
+     If you don't close the files, eventually you may exceed a system
+     limit on the number of open files in one process.  So close each
+     one when you are finished writing it.
+
+   * To make a command finish.  When you redirect output through a pipe,
+     the command reading the pipe normally continues to try to read
+     input as long as the pipe is open.  Often this means the command
+     cannot really do its work until the pipe is closed.  For example,
+     if you redirect output to the `mail' program, the message is not
+     actually sent until the pipe is closed.
+
+   * To run the same program a second time, with the same arguments.
+     This is not the same thing as giving more input to the first run!
+
+     For example, suppose you pipe output to the `mail' program.  If you
+     output several lines redirected to this pipe without closing it,
+     they make a single message of several lines.  By contrast, if you
+     close the pipe after each line of output, then each line makes a
+     separate message.
+
+   `close' returns a value of zero if the close succeeded.  Otherwise,
+the value will be non-zero.  In this case, `gawk' sets the variable
+`ERRNO' to a string describing the error that occurred.
+
+   If you use more files than the system allows you to have open,
+`gawk' will attempt to multiplex the available open files among your
+data files.  `gawk''s ability to do this depends upon the facilities of
+your operating system: it may not always work.  It is therefore both
+good practice and good portability advice to always use `close' on your
+files when you are done with them.
+
+
+File: gawk.info,  Node: Expressions,  Next: Patterns and Actions,  Prev: Printing,  Up: Top
+
+Expressions
+***********
+
+   Expressions are the basic building blocks of `awk' patterns and
+actions.  An expression evaluates to a value, which you can print, test,
+store in a variable or pass to a function.  Additionally, an expression
+can assign a new value to a variable or a field, with an assignment
+operator.
+
+   An expression can serve as a pattern or action statement on its own.
+Most other kinds of statements contain one or more expressions which
+specify data on which to operate.  As in other languages, expressions
+in `awk' include variables, array references, constants, and function
+calls, as well as combinations of these with various operators.
+
+* Menu:
+
+* Constants::                   String, numeric, and regexp constants.
+* Using Constant Regexps::      When and how to use a regexp constant.
+* Variables::                   Variables give names to values for later use.
+* Conversion::                  The conversion of strings to numbers and vice
+                                versa.
+* Arithmetic Ops::              Arithmetic operations (`+', `-',
+                                etc.)
+* Concatenation::               Concatenating strings.
+* Assignment Ops::              Changing the value of a variable or a field.
+* Increment Ops::               Incrementing the numeric value of a variable.
+* Truth Values::                What is ``true'' and what is ``false''.
+* Typing and Comparison::       How variables acquire types, and how this
+                                affects comparison of numbers and strings with
+                                `<', etc.
+* Boolean Ops::                 Combining comparison expressions using boolean
+                                operators `||' (``or''), `&&'
+                                (``and'') and `!' (``not'').
+* Conditional Exp::             Conditional expressions select between two
+                                subexpressions under control of a third
+                                subexpression.
+* Function Calls::              A function call is an expression.
+* Precedence::                  How various operators nest.
+
+
+File: gawk.info,  Node: Constants,  Next: Using Constant Regexps,  Prev: Expressions,  Up: Expressions
+
+Constant Expressions
+====================
+
+   The simplest type of expression is the "constant", which always has
+the same value.  There are three types of constants: numeric constants,
+string constants, and regular expression constants.
+
+* Menu:
+
+* Scalar Constants::            Numeric and string constants.
+* Regexp Constants::            Regular Expression constants.
+
+
+File: gawk.info,  Node: Scalar Constants,  Next: Regexp Constants,  Prev: Constants,  Up: Constants
+
+Numeric and String Constants
+----------------------------
+
+   A "numeric constant" stands for a number.  This number can be an
+integer, a decimal fraction, or a number in scientific (exponential)
+notation.(1) Here are some examples of numeric constants, which all
+have the same value:
+
+     105
+     1.05e+2
+     1050e-1
+
+   A string constant consists of a sequence of characters enclosed in
+double-quote marks.  For example:
+
+     "parrot"
+
+represents the string whose contents are `parrot'.  Strings in `gawk'
+can be of any length and they can contain any of the possible eight-bit
+ASCII characters including ASCII NUL (character code zero).  Other `awk'
+implementations may have difficulty with some character codes.
+
+   ---------- Footnotes ----------
+
+   (1) The internal representation uses double-precision floating point
+numbers. If you don't know what that means, then don't worry about it.
+
+
+File: gawk.info,  Node: Regexp Constants,  Prev: Scalar Constants,  Up: Constants
+
+Regular Expression Constants
+----------------------------
+
+   A regexp constant is a regular expression description enclosed in
+slashes, such as `/^beginning and end$/'.  Most regexps used in `awk'
+programs are constant, but the `~' and `!~' matching operators can also
+match computed or "dynamic" regexps (which are just ordinary strings or
+variables that contain a regexp).
+
+
+File: gawk.info,  Node: Using Constant Regexps,  Next: Variables,  Prev: Constants,  Up: Expressions
+
+Using Regular Expression Constants
+==================================
+
+   When used on the right hand side of the `~' or `!~' operators, a
+regexp constant merely stands for the regexp that is to be matched.
+
+   Regexp constants (such as `/foo/') may be used like simple
+expressions.  When a regexp constant appears by itself, it has the same
+meaning as if it appeared in a pattern, i.e. `($0 ~ /foo/)' (d.c.)
+(*note Expressions as Patterns: Expression Patterns.).  This means that
+the two code segments,
+
+     if ($0 ~ /barfly/ || $0 ~ /camelot/)
+         print "found"
+
+and
+
+     if (/barfly/ || /camelot/)
+         print "found"
+
+are exactly equivalent.
+
+   One rather bizarre consequence of this rule is that the following
+boolean expression is valid, but does not do what the user probably
+intended:
+
+     # note that /foo/ is on the left of the ~
+     if (/foo/ ~ $1) print "found foo"
+
+This code is "obviously" testing `$1' for a match against the regexp
+`/foo/'.  But in fact, the expression `/foo/ ~ $1' actually means `($0
+~ /foo/) ~ $1'.  In other words, first match the input record against
+the regexp `/foo/'.  The result will be either zero or one, depending
+upon the success or failure of the match.  Then match that result
+against the first field in the record.
+
+   Since it is unlikely that you would ever really wish to make this
+kind of test, `gawk' will issue a warning when it sees this construct in
+a program.
+
+   Another consequence of this rule is that the assignment statement
+
+     matches = /foo/
+
+will assign either zero or one to the variable `matches', depending
+upon the contents of the current input record.
+
+   This feature of the language was never well documented until the
+POSIX specification.
+
+   Constant regular expressions are also used as the first argument for
+the `gensub', `sub' and `gsub' functions, and as the second argument of
+the `match' function (*note Built-in Functions for String Manipulation:
+String Functions.).  Modern implementations of `awk', including `gawk',
+allow the third argument of `split' to be a regexp constant, while some
+older implementations do not (d.c.).
+
+   This can lead to confusion when attempting to use regexp constants
+as arguments to user defined functions (*note User-defined Functions:
+User-defined.).  For example:
+
+     function mysub(pat, repl, str, global)
+     {
+         if (global)
+             gsub(pat, repl, str)
+         else
+             sub(pat, repl, str)
+         return str
+     }
+     
+     {
+         ...
+         text = "hi! hi yourself!"
+         mysub(/hi/, "howdy", text, 1)
+         ...
+     }
+
+   In this example, the programmer wishes to pass a regexp constant to
+the user-defined function `mysub', which will in turn pass it on to
+either `sub' or `gsub'.  However, what really happens is that the `pat'
+parameter will be either one or zero, depending upon whether or not
+`$0' matches `/hi/'.
+
+   As it is unlikely that you would ever really wish to pass a truth
+value in this way, `gawk' will issue a warning when it sees a regexp
+constant used as a parameter to a user-defined function.
+
+
+File: gawk.info,  Node: Variables,  Next: Conversion,  Prev: Using Constant Regexps,  Up: Expressions
+
+Variables
+=========
+
+   Variables are ways of storing values at one point in your program for
+use later in another part of your program.  You can manipulate them
+entirely within your program text, and you can also assign values to
+them on the `awk' command line.
+
+* Menu:
+
+* Using Variables::             Using variables in your programs.
+* Assignment Options::          Setting variables on the command line and a
+                                summary of command line syntax. This is an
+                                advanced method of input.
+
+
+File: gawk.info,  Node: Using Variables,  Next: Assignment Options,  Prev: Variables,  Up: Variables
+
+Using Variables in a Program
+----------------------------
+
+   Variables let you give names to values and refer to them later.  You
+have already seen variables in many of the examples.  The name of a
+variable must be a sequence of letters, digits and underscores, but it
+may not begin with a digit.  Case is significant in variable names; `a'
+and `A' are distinct variables.
+
+   A variable name is a valid expression by itself; it represents the
+variable's current value.  Variables are given new values with
+"assignment operators", "increment operators" and "decrement operators".
+*Note Assignment Expressions: Assignment Ops.
+
+   A few variables have special built-in meanings, such as `FS', the
+field separator, and `NF', the number of fields in the current input
+record.  *Note Built-in Variables::, for a list of them.  These
+built-in variables can be used and assigned just like all other
+variables, but their values are also used or changed automatically by
+`awk'.  All built-in variables names are entirely upper-case.
+
+   Variables in `awk' can be assigned either numeric or string values.
+By default, variables are initialized to the empty string, which is
+zero if converted to a number.  There is no need to "initialize" each
+variable explicitly in `awk', the way you would in C and in most other
+traditional languages.
+
+
+File: gawk.info,  Node: Assignment Options,  Prev: Using Variables,  Up: Variables
+
+Assigning Variables on the Command Line
+---------------------------------------
+
+   You can set any `awk' variable by including a "variable assignment"
+among the arguments on the command line when you invoke `awk' (*note
+Other Command Line Arguments: Other Arguments.).  Such an assignment has
+this form:
+
+     VARIABLE=TEXT
+
+With it, you can set a variable either at the beginning of the `awk'
+run or in between input files.
+
+   If you precede the assignment with the `-v' option, like this:
+
+     -v VARIABLE=TEXT
+
+then the variable is set at the very beginning, before even the `BEGIN'
+rules are run.  The `-v' option and its assignment must precede all the
+file name arguments, as well as the program text.  (*Note Command Line
+Options: Options, for more information about the `-v' option.)
+
+   Otherwise, the variable assignment is performed at a time determined
+by its position among the input file arguments: after the processing of
+the preceding input file argument.  For example:
+
+     awk '{ print $n }' n=4 inventory-shipped n=2 BBS-list
+
+prints the value of field number `n' for all input records.  Before the
+first file is read, the command line sets the variable `n' equal to
+four.  This causes the fourth field to be printed in lines from the
+file `inventory-shipped'.  After the first file has finished, but
+before the second file is started, `n' is set to two, so that the
+second field is printed in lines from `BBS-list'.
+
+     $ awk '{ print $n }' n=4 inventory-shipped n=2 BBS-list
+     -| 15
+     -| 24
+     ...
+     -| 555-5553
+     -| 555-3412
+     ...
+
+   Command line arguments are made available for explicit examination by
+the `awk' program in an array named `ARGV' (*note Using `ARGC' and
+`ARGV': ARGC and ARGV.).
+
+   `awk' processes the values of command line assignments for escape
+sequences (d.c.) (*note Escape Sequences::).
+
+
+File: gawk.info,  Node: Conversion,  Next: Arithmetic Ops,  Prev: Variables,  Up: Expressions
+
+Conversion of Strings and Numbers
+=================================
+
+   Strings are converted to numbers, and numbers to strings, if the
+context of the `awk' program demands it.  For example, if the value of
+either `foo' or `bar' in the expression `foo + bar' happens to be a
+string, it is converted to a number before the addition is performed.
+If numeric values appear in string concatenation, they are converted to
+strings.  Consider this:
+
+     two = 2; three = 3
+     print (two three) + 4
+
+This prints the (numeric) value 27.  The numeric values of the
+variables `two' and `three' are converted to strings and concatenated
+together, and the resulting string is converted back to the number 23,
+to which four is then added.
+
+   If, for some reason, you need to force a number to be converted to a
+string, concatenate the empty string, `""', with that number.  To force
+a string to be converted to a number, add zero to that string.
+
+   A string is converted to a number by interpreting any numeric prefix
+of the string as numerals: `"2.5"' converts to 2.5, `"1e3"' converts to
+1000, and `"25fix"' has a numeric value of 25.  Strings that can't be
+interpreted as valid numbers are converted to zero.
+
+   The exact manner in which numbers are converted into strings is
+controlled by the `awk' built-in variable `CONVFMT' (*note Built-in
+Variables::).  Numbers are converted using the `sprintf' function
+(*note Built-in Functions for String Manipulation: String Functions.)
+with `CONVFMT' as the format specifier.
+
+   `CONVFMT''s default value is `"%.6g"', which prints a value with at
+least six significant digits.  For some applications you will want to
+change it to specify more precision.  Double precision on most modern
+machines gives you 16 or 17 decimal digits of precision.
+
+   Strange results can happen if you set `CONVFMT' to a string that
+doesn't tell `sprintf' how to format floating point numbers in a useful
+way.  For example, if you forget the `%' in the format, all numbers
+will be converted to the same constant string.
+
+   As a special case, if a number is an integer, then the result of
+converting it to a string is _always_ an integer, no matter what the
+value of `CONVFMT' may be.  Given the following code fragment:
+
+     CONVFMT = "%2.2f"
+     a = 12
+     b = a ""
+
+`b' has the value `"12"', not `"12.00"' (d.c.).
+
+   Prior to the POSIX standard, `awk' specified that the value of
+`OFMT' was used for converting numbers to strings.  `OFMT' specifies
+the output format to use when printing numbers with `print'.  `CONVFMT'
+was introduced in order to separate the semantics of conversion from
+the semantics of printing.  Both `CONVFMT' and `OFMT' have the same
+default value: `"%.6g"'.  In the vast majority of cases, old `awk'
+programs will not change their behavior.  However, this use of `OFMT'
+is something to keep in mind if you must port your program to other
+implementations of `awk'; we recommend that instead of changing your
+programs, you just port `gawk' itself!  *Note The `print' Statement:
+Print, for more information on the `print' statement.
+
+
+File: gawk.info,  Node: Arithmetic Ops,  Next: Concatenation,  Prev: Conversion,  Up: Expressions
+
+Arithmetic Operators
+====================
+
+   The `awk' language uses the common arithmetic operators when
+evaluating expressions.  All of these arithmetic operators follow normal
+precedence rules, and work as you would expect them to.
+
+   Here is a file `grades' containing a list of student names and three
+test scores per student (it's a small class):
+
+     Pat   100 97 58
+     Sandy  84 72 93
+     Chris  72 92 89
+
+This programs takes the file `grades', and prints the average of the
+scores.
+
+     $ awk '{ sum = $2 + $3 + $4 ; avg = sum / 3
+     >        print $1, avg }' grades
+     -| Pat 85
+     -| Sandy 83
+     -| Chris 84.3333
+
+   This table lists the arithmetic operators in `awk', in order from
+highest precedence to lowest:
+
+`- X'
+     Negation.
+
+`+ X'
+     Unary plus.  The expression is converted to a number.
+
+`X ^ Y'
+`X ** Y'
+     Exponentiation: X raised to the Y power.  `2 ^ 3' has the value
+     eight.  The character sequence `**' is equivalent to `^'.  (The
+     POSIX standard only specifies the use of `^' for exponentiation.)
+
+`X * Y'
+     Multiplication.
+
+`X / Y'
+     Division.  Since all numbers in `awk' are real numbers, the result
+     is not rounded to an integer: `3 / 4' has the value 0.75.
+
+`X % Y'
+     Remainder.  The quotient is rounded toward zero to an integer,
+     multiplied by Y and this result is subtracted from X.  This
+     operation is sometimes known as "trunc-mod."  The following
+     relation always holds:
+
+          b * int(a / b) + (a % b) == a
+
+     One possibly undesirable effect of this definition of remainder is
+     that `X % Y' is negative if X is negative.  Thus,
+
+          -17 % 8 = -1
+
+     In other `awk' implementations, the signedness of the remainder
+     may be machine dependent.
+
+`X + Y'
+     Addition.
+
+`X - Y'
+     Subtraction.
+
+   For maximum portability, do not use the `**' operator.
+
+   Unary plus and minus have the same precedence, the multiplication
+operators all have the same precedence, and addition and subtraction
+have the same precedence.
+
+
+File: gawk.info,  Node: Concatenation,  Next: Assignment Ops,  Prev: Arithmetic Ops,  Up: Expressions
+
+String Concatenation
+====================
+
+   There is only one string operation: concatenation.  It does not have
+a specific operator to represent it.  Instead, concatenation is
+performed by writing expressions next to one another, with no operator.
+For example:
+
+     $ awk '{ print "Field number one: " $1 }' BBS-list
+     -| Field number one: aardvark
+     -| Field number one: alpo-net
+     ...
+
+   Without the space in the string constant after the `:', the line
+would run together.  For example:
+
+     $ awk '{ print "Field number one:" $1 }' BBS-list
+     -| Field number one:aardvark
+     -| Field number one:alpo-net
+     ...
+
+   Since string concatenation does not have an explicit operator, it is
+often necessary to insure that it happens where you want it to by using
+parentheses to enclose the items to be concatenated.  For example, the
+following code fragment does not concatenate `file' and `name' as you
+might expect:
+
+     file = "file"
+     name = "name"
+     print "something meaningful" > file name
+
+It is necessary to use the following:
+
+     print "something meaningful" > (file name)
+
+   We recommend that you use parentheses around concatenation in all
+but the most common contexts (such as on the right-hand side of `=').
+
+
+File: gawk.info,  Node: Assignment Ops,  Next: Increment Ops,  Prev: Concatenation,  Up: Expressions
+
+Assignment Expressions
+======================
+
+   An "assignment" is an expression that stores a new value into a
+variable.  For example, let's assign the value one to the variable `z':
+
+     z = 1
+
+   After this expression is executed, the variable `z' has the value
+one.  Whatever old value `z' had before the assignment is forgotten.
+
+   Assignments can store string values also.  For example, this would
+store the value `"this food is good"' in the variable `message':
+
+     thing = "food"
+     predicate = "good"
+     message = "this " thing " is " predicate
+
+(This also illustrates string concatenation.)
+
+   The `=' sign is called an "assignment operator".  It is the simplest
+assignment operator because the value of the right-hand operand is
+stored unchanged.
+
+   Most operators (addition, concatenation, and so on) have no effect
+except to compute a value.  If you ignore the value, you might as well
+not use the operator.  An assignment operator is different; it does
+produce a value, but even if you ignore the value, the assignment still
+makes itself felt through the alteration of the variable.  We call this
+a "side effect".
+
+   The left-hand operand of an assignment need not be a variable (*note
+Variables::); it can also be a field (*note Changing the Contents of a
+Field: Changing Fields.) or an array element (*note Arrays in `awk':
+Arrays.).  These are all called "lvalues", which means they can appear
+on the left-hand side of an assignment operator.  The right-hand
+operand may be any expression; it produces the new value which the
+assignment stores in the specified variable, field or array element.
+(Such values are called "rvalues").
+
+   It is important to note that variables do _not_ have permanent types.
+The type of a variable is simply the type of whatever value it happens
+to hold at the moment.  In the following program fragment, the variable
+`foo' has a numeric value at first, and a string value later on:
+
+     foo = 1
+     print foo
+     foo = "bar"
+     print foo
+
+When the second assignment gives `foo' a string value, the fact that it
+previously had a numeric value is forgotten.
+
+   String values that do not begin with a digit have a numeric value of
+zero. After executing this code, the value of `foo' is five:
+
+     foo = "a string"
+     foo = foo + 5
+
+(Note that using a variable as a number and then later as a string can
+be confusing and is poor programming style.  The above examples
+illustrate how `awk' works, _not_ how you should write your own
+programs!)
+
+   An assignment is an expression, so it has a value: the same value
+that is assigned.  Thus, `z = 1' as an expression has the value one.
+One consequence of this is that you can write multiple assignments
+together:
+
+     x = y = z = 0
+
+stores the value zero in all three variables.  It does this because the
+value of `z = 0', which is zero, is stored into `y', and then the value
+of `y = z = 0', which is zero, is stored into `x'.
+
+   You can use an assignment anywhere an expression is called for.  For
+example, it is valid to write `x != (y = 1)' to set `y' to one and then
+test whether `x' equals one.  But this style tends to make programs
+hard to read; except in a one-shot program, you should not use such
+nesting of assignments.
+
+   Aside from `=', there are several other assignment operators that do
+arithmetic with the old value of the variable.  For example, the
+operator `+=' computes a new value by adding the right-hand value to
+the old value of the variable.  Thus, the following assignment adds
+five to the value of `foo':
+
+     foo += 5
+
+This is equivalent to the following:
+
+     foo = foo + 5
+
+Use whichever one makes the meaning of your program clearer.
+
+   There are situations where using `+=' (or any assignment operator)
+is _not_ the same as simply repeating the left-hand operand in the
+right-hand expression.  For example:
+
+     # Thanks to Pat Rankin for this example
+     BEGIN  {
+         foo[rand()] += 5
+         for (x in foo)
+            print x, foo[x]
+     
+         bar[rand()] = bar[rand()] + 5
+         for (x in bar)
+            print x, bar[x]
+     }
+
+The indices of `bar' are guaranteed to be different, because `rand'
+will return different values each time it is called.  (Arrays and the
+`rand' function haven't been covered yet.  *Note Arrays in `awk':
+Arrays, and see *Note Numeric Built-in Functions: Numeric Functions,
+for more information).  This example illustrates an important fact
+about the assignment operators: the left-hand expression is only
+evaluated _once_.
+
+   It is also up to the implementation as to which expression is
+evaluated first, the left-hand one or the right-hand one.  Consider
+this example:
+
+     i = 1
+     a[i += 2] = i + 1
+
+The value of `a[3]' could be either two or four.
+
+   Here is a table of the arithmetic assignment operators.  In each
+case, the right-hand operand is an expression whose value is converted
+to a number.
+
+`LVALUE += INCREMENT'
+     Adds INCREMENT to the value of LVALUE to make the new value of
+     LVALUE.
+
+`LVALUE -= DECREMENT'
+     Subtracts DECREMENT from the value of LVALUE.
+
+`LVALUE *= COEFFICIENT'
+     Multiplies the value of LVALUE by COEFFICIENT.
+
+`LVALUE /= DIVISOR'
+     Divides the value of LVALUE by DIVISOR.
+
+`LVALUE %= MODULUS'
+     Sets LVALUE to its remainder by MODULUS.
+
+`LVALUE ^= POWER'
+`LVALUE **= POWER'
+     Raises LVALUE to the power POWER.  (Only the `^=' operator is
+     specified by POSIX.)
+
+   For maximum portability, do not use the `**=' operator.
+
+
+File: gawk.info,  Node: Increment Ops,  Next: Truth Values,  Prev: Assignment Ops,  Up: Expressions
+
+Increment and Decrement Operators
+=================================
+
+   "Increment" and "decrement operators" increase or decrease the value
+of a variable by one.  You could do the same thing with an assignment
+operator, so the increment operators add no power to the `awk'
+language; but they are convenient abbreviations for very common
+operations.
+
+   The operator to add one is written `++'.  It can be used to increment
+a variable either before or after taking its value.
+
+   To pre-increment a variable V, write `++V'.  This adds one to the
+value of V and that new value is also the value of this expression.
+The assignment expression `V += 1' is completely equivalent.
+
+   Writing the `++' after the variable specifies post-increment.  This
+increments the variable value just the same; the difference is that the
+value of the increment expression itself is the variable's _old_ value.
+Thus, if `foo' has the value four, then the expression `foo++' has the
+value four, but it changes the value of `foo' to five.
+
+   The post-increment `foo++' is nearly equivalent to writing `(foo +=
+1) - 1'.  It is not perfectly equivalent because all numbers in `awk'
+are floating point: in floating point, `foo + 1 - 1' does not
+necessarily equal `foo'.  But the difference is minute as long as you
+stick to numbers that are fairly small (less than 10e12).
+
+   Any lvalue can be incremented.  Fields and array elements are
+incremented just like variables.  (Use `$(i++)' when you wish to do a
+field reference and a variable increment at the same time.  The
+parentheses are necessary because of the precedence of the field
+reference operator, `$'.)
+
+   The decrement operator `--' works just like `++' except that it
+subtracts one instead of adding.  Like `++', it can be used before the
+lvalue to pre-decrement or after it to post-decrement.
+
+   Here is a summary of increment and decrement expressions.
+
+`++LVALUE'
+     This expression increments LVALUE and the new value becomes the
+     value of the expression.
+
+`LVALUE++'
+     This expression increments LVALUE, but the value of the expression
+     is the _old_ value of LVALUE.
+
+`--LVALUE'
+     Like `++LVALUE', but instead of adding, it subtracts.  It
+     decrements LVALUE and delivers the value that results.
+
+`LVALUE--'
+     Like `LVALUE++', but instead of adding, it subtracts.  It
+     decrements LVALUE.  The value of the expression is the _old_ value
+     of LVALUE.
+
+
+File: gawk.info,  Node: Truth Values,  Next: Typing and Comparison,  Prev: Increment Ops,  Up: Expressions
+
+True and False in `awk'
+=======================
+
+   Many programming languages have a special representation for the
+concepts of "true" and "false."  Such languages usually use the special
+constants `true' and `false', or perhaps their upper-case equivalents.
+
+   `awk' is different.  It borrows a very simple concept of true and
+false from C.  In `awk', any non-zero numeric value, _or_ any non-empty
+string value is true.  Any other value (zero or the null string, `""')
+is false.  The following program will print `A strange truth value'
+three times:
+
+     BEGIN {
+        if (3.1415927)
+            print "A strange truth value"
+        if ("Four Score And Seven Years Ago")
+            print "A strange truth value"
+        if (j = 57)
+            print "A strange truth value"
+     }
+
+   There is a surprising consequence of the "non-zero or non-null" rule:
+The string constant `"0"' is actually true, since it is non-null (d.c.).
+
+
+File: gawk.info,  Node: Typing and Comparison,  Next: Boolean Ops,  Prev: Truth Values,  Up: Expressions
+
+Variable Typing and Comparison Expressions
+==========================================
+
+   Unlike other programming languages, `awk' variables do not have a
+fixed type. Instead, they can be either a number or a string, depending
+upon the value that is assigned to them.
+
+   The 1992 POSIX standard introduced the concept of a "numeric
+string", which is simply a string that looks like a number, for
+example, `" +2"'.  This concept is used for determining the type of a
+variable.
+
+   The type of the variable is important, since the types of two
+variables determine how they are compared.
+
+   In `gawk', variable typing follows these rules.
+
+  1. A numeric literal or the result of a numeric operation has the
+     NUMERIC attribute.
+
+  2. A string literal or the result of a string operation has the STRING
+     attribute.
+
+  3. Fields, `getline' input, `FILENAME', `ARGV' elements, `ENVIRON'
+     elements and the elements of an array created by `split' that are
+     numeric strings have the STRNUM attribute.  Otherwise, they have
+     the STRING attribute.  Uninitialized variables also have the
+     STRNUM attribute.
+
+  4. Attributes propagate across assignments, but are not changed by
+     any use.
+
+   The last rule is particularly important. In the following program,
+`a' has numeric type, even though it is later used in a string
+operation.
+
+     BEGIN {
+              a = 12.345
+              b = a " is a cute number"
+              print b
+     }
+
+   When two operands are compared, either string comparison or numeric
+comparison may be used, depending on the attributes of the operands,
+according to the following, symmetric, matrix:
+
+     	+----------------------------------------------
+     	|	STRING		NUMERIC		STRNUM
+     --------+----------------------------------------------
+     	|
+     STRING	|	string		string		string
+     	|
+     NUMERIC	|	string		numeric		numeric
+     	|
+     STRNUM	|	string		numeric		numeric
+     --------+----------------------------------------------
+
+   The basic idea is that user input that looks numeric, and _only_
+user input, should be treated as numeric, even though it is actually
+made of characters, and is therefore also a string.
+
+   "Comparison expressions" compare strings or numbers for
+relationships such as equality.  They are written using "relational
+operators", which are a superset of those in C.  Here is a table of
+them:
+
+`X < Y'
+     True if X is less than Y.
+
+`X <= Y'
+     True if X is less than or equal to Y.
+
+`X > Y'
+     True if X is greater than Y.
+
+`X >= Y'
+     True if X is greater than or equal to Y.
+
+`X == Y'
+     True if X is equal to Y.
+
+`X != Y'
+     True if X is not equal to Y.
+
+`X ~ Y'
+     True if the string X matches the regexp denoted by Y.
+
+`X !~ Y'
+     True if the string X does not match the regexp denoted by Y.
+
+`SUBSCRIPT in ARRAY'
+     True if the array ARRAY has an element with the subscript
+     SUBSCRIPT.
+
+   Comparison expressions have the value one if true and zero if false.
+
+   When comparing operands of mixed types, numeric operands are
+converted to strings using the value of `CONVFMT' (*note Conversion of
+Strings and Numbers: Conversion.).
+
+   Strings are compared by comparing the first character of each, then
+the second character of each, and so on.  Thus `"10"' is less than
+`"9"'.  If there are two strings where one is a prefix of the other,
+the shorter string is less than the longer one.  Thus `"abc"' is less
+than `"abcd"'.
+
+   It is very easy to accidentally mistype the `==' operator, and leave
+off one of the `='s.  The result is still valid `awk' code, but the
+program will not do what you mean:
+
+     if (a = b)   # oops! should be a == b
+        ...
+     else
+        ...
+
+Unless `b' happens to be zero or the null string, the `if' part of the
+test will always succeed.  Because the operators are so similar, this
+kind of error is very difficult to spot when scanning the source code.
+
+   Here are some sample expressions, how `gawk' compares them, and what
+the result of the comparison is.
+
+`1.5 <= 2.0'
+     numeric comparison (true)
+
+`"abc" >= "xyz"'
+     string comparison (false)
+
+`1.5 != " +2"'
+     string comparison (true)
+
+`"1e2" < "3"'
+     string comparison (true)
+
+`a = 2; b = "2"'
+`a == b'
+     string comparison (true)
+
+`a = 2; b = " +2"'
+`a == b'
+     string comparison (false)
+
+   In this example,
+
+     $ echo 1e2 3 | awk '{ print ($1 < $2) ? "true" : "false" }'
+     -| false
+
+the result is `false' since both `$1' and `$2' are numeric strings and
+thus both have the STRNUM attribute, dictating a numeric comparison.
+
+   The purpose of the comparison rules and the use of numeric strings is
+to attempt to produce the behavior that is "least surprising," while
+still "doing the right thing."
+
+   String comparisons and regular expression comparisons are very
+different.  For example,
+
+     x == "foo"
+
+has the value of one, or is true, if the variable `x' is precisely
+`foo'.  By contrast,
+
+     x ~ /foo/
+
+has the value one if `x' contains `foo', such as `"Oh, what a fool am
+I!"'.
+
+   The right hand operand of the `~' and `!~' operators may be either a
+regexp constant (`/.../'), or an ordinary expression, in which case the
+value of the expression as a string is used as a dynamic regexp (*note
+How to Use Regular Expressions: Regexp Usage.; also *note Using Dynamic
+Regexps: Computed Regexps.).
+
+   In recent implementations of `awk', a constant regular expression in
+slashes by itself is also an expression.  The regexp `/REGEXP/' is an
+abbreviation for this comparison expression:
+
+     $0 ~ /REGEXP/
+
+   One special place where `/foo/' is _not_ an abbreviation for `$0 ~
+/foo/' is when it is the right-hand operand of `~' or `!~'!  *Note
+Using Regular Expression Constants: Using Constant Regexps, where this
+is discussed in more detail.
+
+
+File: gawk.info,  Node: Boolean Ops,  Next: Conditional Exp,  Prev: Typing and Comparison,  Up: Expressions
+
+Boolean Expressions
+===================
+
+   A "boolean expression" is a combination of comparison expressions or
+matching expressions, using the boolean operators "or" (`||'), "and"
+(`&&'), and "not" (`!'), along with parentheses to control nesting.
+The truth value of the boolean expression is computed by combining the
+truth values of the component expressions.  Boolean expressions are
+also referred to as "logical expressions".  The terms are equivalent.
+
+   Boolean expressions can be used wherever comparison and matching
+expressions can be used.  They can be used in `if', `while', `do' and
+`for' statements (*note Control Statements in Actions: Statements.).
+They have numeric values (one if true, zero if false), which come into
+play if the result of the boolean expression is stored in a variable, or
+used in arithmetic.
+
+   In addition, every boolean expression is also a valid pattern, so
+you can use one as a pattern to control the execution of rules.
+
+   Here are descriptions of the three boolean operators, with examples.
+
+`BOOLEAN1 && BOOLEAN2'
+     True if both BOOLEAN1 and BOOLEAN2 are true.  For example, the
+     following statement prints the current input record if it contains
+     both `2400' and `foo'.
+
+          if ($0 ~ /2400/ && $0 ~ /foo/) print
+
+     The subexpression BOOLEAN2 is evaluated only if BOOLEAN1 is true.
+     This can make a difference when BOOLEAN2 contains expressions that
+     have side effects: in the case of `$0 ~ /foo/ && ($2 == bar++)',
+     the variable `bar' is not incremented if there is no `foo' in the
+     record.
+
+`BOOLEAN1 || BOOLEAN2'
+     True if at least one of BOOLEAN1 or BOOLEAN2 is true.  For
+     example, the following statement prints all records in the input
+     that contain _either_ `2400' or `foo', or both.
+
+          if ($0 ~ /2400/ || $0 ~ /foo/) print
+
+     The subexpression BOOLEAN2 is evaluated only if BOOLEAN1 is false.
+     This can make a difference when BOOLEAN2 contains expressions
+     that have side effects.
+
+`! BOOLEAN'
+     True if BOOLEAN is false.  For example, the following program
+     prints all records in the input file `BBS-list' that do _not_
+     contain the string `foo'.
+
+          awk '{ if (! ($0 ~ /foo/)) print }' BBS-list
+
+   The `&&' and `||' operators are called "short-circuit" operators
+because of the way they work.  Evaluation of the full expression is
+"short-circuited" if the result can be determined part way through its
+evaluation.
+
+   You can continue a statement that uses `&&' or `||' simply by
+putting a newline after them.  But you cannot put a newline in front of
+either of these operators without using backslash continuation (*note
+`awk' Statements Versus Lines: Statements/Lines.).
+
+   The actual value of an expression using the `!' operator will be
+either one or zero, depending upon the truth value of the expression it
+is applied to.
+
+   The `!' operator is often useful for changing the sense of a flag
+variable from false to true and back again. For example, the following
+program is one way to print lines in between special bracketing lines:
+
+     $1 == "START"   { interested = ! interested }
+     interested == 1 { print }
+     $1 == "END"     { interested = ! interested }
+
+The variable `interested', like all `awk' variables, starts out
+initialized to zero, which is also false.  When a line is seen whose
+first field is `START', the value of `interested' is toggled to true,
+using `!'. The next rule prints lines as long as `interested' is true.
+When a line is seen whose first field is `END', `interested' is toggled
+back to false.
+
+
+File: gawk.info,  Node: Conditional Exp,  Next: Function Calls,  Prev: Boolean Ops,  Up: Expressions
+
+Conditional Expressions
+=======================
+
+   A "conditional expression" is a special kind of expression with
+three operands.  It allows you to use one expression's value to select
+one of two other expressions.
+
+   The conditional expression is the same as in the C language:
+
+     SELECTOR ? IF-TRUE-EXP : IF-FALSE-EXP
+
+There are three subexpressions.  The first, SELECTOR, is always
+computed first.  If it is "true" (not zero and not null) then
+IF-TRUE-EXP is computed next and its value becomes the value of the
+whole expression.  Otherwise, IF-FALSE-EXP is computed next and its
+value becomes the value of the whole expression.
+
+   For example, this expression produces the absolute value of `x':
+
+     x > 0 ? x : -x
+
+   Each time the conditional expression is computed, exactly one of
+IF-TRUE-EXP and IF-FALSE-EXP is computed; the other is ignored.  This
+is important when the expressions contain side effects.  For example,
+this conditional expression examines element `i' of either array `a' or
+array `b', and increments `i'.
+
+     x == y ? a[i++] : b[i++]
+
+This is guaranteed to increment `i' exactly once, because each time
+only one of the two increment expressions is executed, and the other is
+not.  *Note Arrays in `awk': Arrays, for more information about arrays.
+
+   As a minor `gawk' extension, you can continue a statement that uses
+`?:' simply by putting a newline after either character.  However, you
+cannot put a newline in front of either character without using
+backslash continuation (*note `awk' Statements Versus Lines:
+Statements/Lines.).
+
+
+File: gawk.info,  Node: Function Calls,  Next: Precedence,  Prev: Conditional Exp,  Up: Expressions
+
+Function Calls
+==============
+
+   A "function" is a name for a particular calculation.  Because it has
+a name, you can ask for it by name at any point in the program.  For
+example, the function `sqrt' computes the square root of a number.
+
+   A fixed set of functions are "built-in", which means they are
+available in every `awk' program.  The `sqrt' function is one of these.
+*Note Built-in Functions: Built-in, for a list of built-in functions
+and their descriptions.  In addition, you can define your own functions
+for use in your program.  *Note User-defined Functions: User-defined,
+for how to do this.
+
+   The way to use a function is with a "function call" expression,
+which consists of the function name followed immediately by a list of
+"arguments" in parentheses.  The arguments are expressions which
+provide the raw materials for the function's calculations.  When there
+is more than one argument, they are separated by commas.  If there are
+no arguments, write just `()' after the function name.  Here are some
+examples:
+
+     sqrt(x^2 + y^2)        one argument
+     atan2(y, x)            two arguments
+     rand()                 no arguments
+
+   *Do not put any space between the function name and the
+open-parenthesis!*  A user-defined function name looks just like the
+name of a variable, and space would make the expression look like
+concatenation of a variable with an expression inside parentheses.
+Space before the parenthesis is harmless with built-in functions, but
+it is best not to get into the habit of using space to avoid mistakes
+with user-defined functions.
+
+   Each function expects a particular number of arguments.  For
+example, the `sqrt' function must be called with a single argument, the
+number to take the square root of:
+
+     sqrt(ARGUMENT)
+
+   Some of the built-in functions allow you to omit the final argument.
+If you do so, they use a reasonable default.  *Note Built-in Functions:
+Built-in, for full details.  If arguments are omitted in calls to
+user-defined functions, then those arguments are treated as local
+variables, initialized to the empty string (*note User-defined
+Functions: User-defined.).
+
+   Like every other expression, the function call has a value, which is
+computed by the function based on the arguments you give it.  In this
+example, the value of `sqrt(ARGUMENT)' is the square root of ARGUMENT.
+A function can also have side effects, such as assigning values to
+certain variables or doing I/O.
+
+   Here is a command to read numbers, one number per line, and print the
+square root of each one:
+
+     $ awk '{ print "The square root of", $1, "is", sqrt($1) }'
+     1
+     -| The square root of 1 is 1
+     3
+     -| The square root of 3 is 1.73205
+     5
+     -| The square root of 5 is 2.23607
+     Control-d
+
+
+File: gawk.info,  Node: Precedence,  Prev: Function Calls,  Up: Expressions
+
+Operator Precedence (How Operators Nest)
+========================================
+
+   "Operator precedence" determines how operators are grouped, when
+different operators appear close by in one expression.  For example,
+`*' has higher precedence than `+'; thus, `a + b * c' means to multiply
+`b' and `c', and then add `a' to the product (i.e. `a + (b * c)').
+
+   You can overrule the precedence of the operators by using
+parentheses.  You can think of the precedence rules as saying where the
+parentheses are assumed to be if you do not write parentheses yourself.
+In fact, it is wise to always use parentheses whenever you have an
+unusual combination of operators, because other people who read the
+program may not remember what the precedence is in this case.  You
+might forget, too; then you could make a mistake.  Explicit parentheses
+will help prevent any such mistake.
+
+   When operators of equal precedence are used together, the leftmost
+operator groups first, except for the assignment, conditional and
+exponentiation operators, which group in the opposite order.  Thus, `a
+- b + c' groups as `(a - b) + c', and `a = b = c' groups as `a = (b =
+c)'.
+
+   The precedence of prefix unary operators does not matter as long as
+only unary operators are involved, because there is only one way to
+interpret them--innermost first.  Thus, `$++i' means `$(++i)' and
+`++$x' means `++($x)'.  However, when another operator follows the
+operand, then the precedence of the unary operators can matter.  Thus,
+`$x^2' means `($x)^2', but `-x^2' means `-(x^2)', because `-' has lower
+precedence than `^' while `$' has higher precedence.
+
+   Here is a table of `awk''s operators, in order from highest
+precedence to lowest:
+
+`(...)'
+     Grouping.
+
+`$'
+     Field.
+
+`++ --'
+     Increment, decrement.
+
+`^ **'
+     Exponentiation.  These operators group right-to-left.  (The `**'
+     operator is not specified by POSIX.)
+
+`+ - !'
+     Unary plus, minus, logical "not".
+
+`* / %'
+     Multiplication, division, modulus.
+
+`+ -'
+     Addition, subtraction.
+
+`Concatenation'
+     No special token is used to indicate concatenation.  The operands
+     are simply written side by side.
+
+`< <= == !='
+`> >= >> |'
+     Relational, and redirection.  The relational operators and the
+     redirections have the same precedence level.  Characters such as
+     `>' serve both as relationals and as redirections; the context
+     distinguishes between the two meanings.
+
+     Note that the I/O redirection operators in `print' and `printf'
+     statements belong to the statement level, not to expressions.  The
+     redirection does not produce an expression which could be the
+     operand of another operator.  As a result, it does not make sense
+     to use a redirection operator near another operator of lower
+     precedence, without parentheses.  Such combinations, for example
+     `print foo > a ? b : c', result in syntax errors.  The correct way
+     to write this statement is `print foo > (a ? b : c)'.
+
+`~ !~'
+     Matching, non-matching.
+
+`in'
+     Array membership.
+
+`&&'
+     Logical "and".
+
+`||'
+     Logical "or".
+
+`?:'
+     Conditional.  This operator groups right-to-left.
+
+`= += -= *='
+`/= %= ^= **='
+     Assignment.  These operators group right-to-left.  (The `**='
+     operator is not specified by POSIX.)
+
+
+File: gawk.info,  Node: Patterns and Actions,  Next: Statements,  Prev: Expressions,  Up: Top
+
+Patterns and Actions
+********************
+
+   As you have already seen, each `awk' statement consists of a pattern
+with an associated action.  This chapter describes how you build
+patterns and actions.
+
+* Menu:
+
+* Pattern Overview::            What goes into a pattern.
+* Action Overview::             What goes into an action.
+
+
+File: gawk.info,  Node: Pattern Overview,  Next: Action Overview,  Prev: Patterns and Actions,  Up: Patterns and Actions
+
+Pattern Elements
+================
+
+   Patterns in `awk' control the execution of rules: a rule is executed
+when its pattern matches the current input record.  This section
+explains all about how to write patterns.
+
+* Menu:
+
+* Kinds of Patterns::           A list of all kinds of patterns.
+* Regexp Patterns::             Using regexps as patterns.
+* Expression Patterns::         Any expression can be used as a pattern.
+* Ranges::                      Pairs of patterns specify record ranges.
+* BEGIN/END::                   Specifying initialization and cleanup rules.
+* Empty::                       The empty pattern, which matches every record.
+
+
+File: gawk.info,  Node: Kinds of Patterns,  Next: Regexp Patterns,  Prev: Pattern Overview,  Up: Pattern Overview
+
+Kinds of Patterns
+-----------------
+
+   Here is a summary of the types of patterns supported in `awk'.
+
+`/REGULAR EXPRESSION/'
+     A regular expression as a pattern.  It matches when the text of the
+     input record fits the regular expression.  (*Note Regular
+     Expressions: Regexp.)
+
+`EXPRESSION'
+     A single expression.  It matches when its value is non-zero (if a
+     number) or non-null (if a string).  (*Note Expressions as
+     Patterns: Expression Patterns.)
+
+`PAT1, PAT2'
+     A pair of patterns separated by a comma, specifying a range of
+     records.  The range includes both the initial record that matches
+     PAT1, and the final record that matches PAT2.  (*Note Specifying
+     Record Ranges with Patterns: Ranges.)
+
+`BEGIN'
+`END'
+     Special patterns for you to supply start-up or clean-up actions
+     for your `awk' program.  (*Note The `BEGIN' and `END' Special
+     Patterns: BEGIN/END.)
+
+`EMPTY'
+     The empty pattern matches every input record.  (*Note The Empty
+     Pattern: Empty.)
+
+
+File: gawk.info,  Node: Regexp Patterns,  Next: Expression Patterns,  Prev: Kinds of Patterns,  Up: Pattern Overview
+
+Regular Expressions as Patterns
+-------------------------------
+
+   We have been using regular expressions as patterns since our early
+examples.  This kind of pattern is simply a regexp constant in the
+pattern part of a rule.  Its  meaning is `$0 ~ /PATTERN/'.  The pattern
+matches when the input record matches the regexp.  For example:
+
+     /foo|bar|baz/  { buzzwords++ }
+     END            { print buzzwords, "buzzwords seen" }
+
+
+File: gawk.info,  Node: Expression Patterns,  Next: Ranges,  Prev: Regexp Patterns,  Up: Pattern Overview
+
+Expressions as Patterns
+-----------------------
+
+   Any `awk' expression is valid as an `awk' pattern.  Then the pattern
+matches if the expression's value is non-zero (if a number) or non-null
+(if a string).
+
+   The expression is reevaluated each time the rule is tested against a
+new input record.  If the expression uses fields such as `$1', the
+value depends directly on the new input record's text; otherwise, it
+depends only on what has happened so far in the execution of the `awk'
+program, but that may still be useful.
+
+   A very common kind of expression used as a pattern is the comparison
+expression, using the comparison operators described in *Note Variable
+Typing and Comparison Expressions: Typing and Comparison.
+
+   Regexp matching and non-matching are also very common expressions.
+The left operand of the `~' and `!~' operators is a string.  The right
+operand is either a constant regular expression enclosed in slashes
+(`/REGEXP/'), or any expression, whose string value is used as a
+dynamic regular expression (*note Using Dynamic Regexps: Computed
+Regexps.).
+
+   The following example prints the second field of each input record
+whose first field is precisely `foo'.
+
+     $ awk '$1 == "foo" { print $2 }' BBS-list
+
+(There is no output, since there is no BBS site named "foo".)  Contrast
+this with the following regular expression match, which would accept
+any record with a first field that contains `foo':
+
+     $ awk '$1 ~ /foo/ { print $2 }' BBS-list
+     -| 555-1234
+     -| 555-6699
+     -| 555-6480
+     -| 555-2127
+
+   Boolean expressions are also commonly used as patterns.  Whether the
+pattern matches an input record depends on whether its subexpressions
+match.
+
+   For example, the following command prints all records in `BBS-list'
+that contain both `2400' and `foo'.
+
+     $ awk '/2400/ && /foo/' BBS-list
+     -| fooey        555-1234     2400/1200/300     B
+
+   The following command prints all records in `BBS-list' that contain
+_either_ `2400' or `foo', or both.
+
+     $ awk '/2400/ || /foo/' BBS-list
+     -| alpo-net     555-3412     2400/1200/300     A
+     -| bites        555-1675     2400/1200/300     A
+     -| fooey        555-1234     2400/1200/300     B
+     -| foot         555-6699     1200/300          B
+     -| macfoo       555-6480     1200/300          A
+     -| sdace        555-3430     2400/1200/300     A
+     -| sabafoo      555-2127     1200/300          C
+
+   The following command prints all records in `BBS-list' that do _not_
+contain the string `foo'.
+
+     $ awk '! /foo/' BBS-list
+     -| aardvark     555-5553     1200/300          B
+     -| alpo-net     555-3412     2400/1200/300     A
+     -| barfly       555-7685     1200/300          A
+     -| bites        555-1675     2400/1200/300     A
+     -| camelot      555-0542     300               C
+     -| core         555-2912     1200/300          C
+     -| sdace        555-3430     2400/1200/300     A
+
+   The subexpressions of a boolean operator in a pattern can be
+constant regular expressions, comparisons, or any other `awk'
+expressions.  Range patterns are not expressions, so they cannot appear
+inside boolean patterns.  Likewise, the special patterns `BEGIN' and
+`END', which never match any input record, are not expressions and
+cannot appear inside boolean patterns.
+
+   A regexp constant as a pattern is also a special case of an
+expression pattern.  `/foo/' as an expression has the value one if `foo'
+appears in the current input record; thus, as a pattern, `/foo/'
+matches any record containing `foo'.
+
+
+File: gawk.info,  Node: Ranges,  Next: BEGIN/END,  Prev: Expression Patterns,  Up: Pattern Overview
+
+Specifying Record Ranges with Patterns
+--------------------------------------
+
+   A "range pattern" is made of two patterns separated by a comma, of
+the form `BEGPAT, ENDPAT'.  It matches ranges of consecutive input
+records.  The first pattern, BEGPAT, controls where the range begins,
+and the second one, ENDPAT, controls where it ends.  For example,
+
+     awk '$1 == "on", $1 == "off"'
+
+prints every record between `on'/`off' pairs, inclusive.
+
+   A range pattern starts out by matching BEGPAT against every input
+record; when a record matches BEGPAT, the range pattern becomes "turned
+on".  The range pattern matches this record.  As long as it stays
+turned on, it automatically matches every input record read.  It also
+matches ENDPAT against every input record; when that succeeds, the
+range pattern is turned off again for the following record.  Then it
+goes back to checking BEGPAT against each record.
+
+   The record that turns on the range pattern and the one that turns it
+off both match the range pattern.  If you don't want to operate on
+these records, you can write `if' statements in the rule's action to
+distinguish them from the records you are interested in.
+
+   It is possible for a pattern to be turned both on and off by the same
+record, if the record satisfies both conditions.  Then the action is
+executed for just that record.
+
+   For example, suppose you have text between two identical markers (say
+the `%' symbol) that you wish to ignore.  You might try to combine a
+range pattern that describes the delimited text with the `next'
+statement (not discussed yet, *note The `next' Statement: Next
+Statement.), which causes `awk' to skip any further processing of the
+current record and start over again with the next input record. Such a
+program would like this:
+
+     /^%$/,/^%$/    { next }
+                    { print }
+
+This program fails because the range pattern is both turned on and
+turned off by the first line with just a `%' on it.  To accomplish this
+task, you must write the program this way, using a flag:
+
+     /^%$/     { skip = ! skip; next }
+     skip == 1 { next } # skip lines with `skip' set
+
+   Note that in a range pattern, the `,' has the lowest precedence (is
+evaluated last) of all the operators.  Thus, for example, the following
+program attempts to combine a range pattern with another, simpler test.
+
+     echo Yes | awk '/1/,/2/ || /Yes/'
+
+   The author of this program intended it to mean `(/1/,/2/) || /Yes/'.
+However, `awk' interprets this as `/1/, (/2/ || /Yes/)'.  This cannot
+be changed or worked around; range patterns do not combine with other
+patterns.
+
+
+File: gawk.info,  Node: BEGIN/END,  Next: Empty,  Prev: Ranges,  Up: Pattern Overview
+
+The `BEGIN' and `END' Special Patterns
+--------------------------------------
+
+   `BEGIN' and `END' are special patterns.  They are not used to match
+input records.  Rather, they supply start-up or clean-up actions for
+your `awk' script.
+
+* Menu:
+
+* Using BEGIN/END::             How and why to use BEGIN/END rules.
+* I/O And BEGIN/END::           I/O issues in BEGIN/END rules.
+
+
+File: gawk.info,  Node: Using BEGIN/END,  Next: I/O And BEGIN/END,  Prev: BEGIN/END,  Up: BEGIN/END
+
+Startup and Cleanup Actions
+...........................
+
+   A `BEGIN' rule is executed, once, before the first input record has
+been read.  An `END' rule is executed, once, after all the input has
+been read.  For example:
+
+     $ awk '
+     > BEGIN { print "Analysis of \"foo\"" }
+     > /foo/ { ++n }
+     > END   { print "\"foo\" appears " n " times." }' BBS-list
+     -| Analysis of "foo"
+     -| "foo" appears 4 times.
+
+   This program finds the number of records in the input file `BBS-list'
+that contain the string `foo'.  The `BEGIN' rule prints a title for the
+report.  There is no need to use the `BEGIN' rule to initialize the
+counter `n' to zero, as `awk' does this automatically (*note
+Variables::).
+
+   The second rule increments the variable `n' every time a record
+containing the pattern `foo' is read.  The `END' rule prints the value
+of `n' at the end of the run.
+
+   The special patterns `BEGIN' and `END' cannot be used in ranges or
+with boolean operators (indeed, they cannot be used with any operators).
+
+   An `awk' program may have multiple `BEGIN' and/or `END' rules.  They
+are executed in the order they appear, all the `BEGIN' rules at
+start-up and all the `END' rules at termination.  `BEGIN' and `END'
+rules may be intermixed with other rules.  This feature was added in
+the 1987 version of `awk', and is included in the POSIX standard.  The
+original (1978) version of `awk' required you to put the `BEGIN' rule
+at the beginning of the program, and the `END' rule at the end, and
+only allowed one of each.  This is no longer required, but it is a good
+idea in terms of program organization and readability.
+
+   Multiple `BEGIN' and `END' rules are useful for writing library
+functions, since each library file can have its own `BEGIN' and/or
+`END' rule to do its own initialization and/or cleanup.  Note that the
+order in which library functions are named on the command line controls
+the order in which their `BEGIN' and `END' rules are executed.
+Therefore you have to be careful to write such rules in library files
+so that the order in which they are executed doesn't matter.  *Note
+Command Line Options: Options, for more information on using library
+functions.  *Note A Library of `awk' Functions: Library Functions, for
+a number of useful library functions.
+
+   If an `awk' program only has a `BEGIN' rule, and no other rules,
+then the program exits after the `BEGIN' rule has been run.  (The
+original version of `awk' used to keep reading and ignoring input until
+end of file was seen.)  However, if an `END' rule exists, then the
+input will be read, even if there are no other rules in the program.
+This is necessary in case the `END' rule checks the `FNR' and `NR'
+variables (d.c.).
+
+   `BEGIN' and `END' rules must have actions; there is no default
+action for these rules since there is no current record when they run.
+
+
+File: gawk.info,  Node: I/O And BEGIN/END,  Prev: Using BEGIN/END,  Up: BEGIN/END
+
+Input/Output from `BEGIN' and `END' Rules
+.........................................
+
+   There are several (sometimes subtle) issues involved when doing I/O
+from a `BEGIN' or `END' rule.
+
+   The first has to do with the value of `$0' in a `BEGIN' rule.  Since
+`BEGIN' rules are executed before any input is read, there simply is no
+input record, and therefore no fields, when executing `BEGIN' rules.
+References to `$0' and the fields yield a null string or zero,
+depending upon the context.  One way to give `$0' a real value is to
+execute a `getline' command without a variable (*note Explicit Input
+with `getline': Getline.).  Another way is to simply assign a value to
+it.
+
+   The second point is similar to the first, but from the other
+direction.  Inside an `END' rule, what is the value of `$0' and `NF'?
+Traditionally, due largely to implementation issues, `$0' and `NF' were
+_undefined_ inside an `END' rule.  The POSIX standard specified that
+`NF' was available in an `END' rule, containing the number of fields
+from the last input record.  Due most probably to an oversight, the
+standard does not say that `$0' is also preserved, although logically
+one would think that it should be.  In fact, `gawk' does preserve the
+value of `$0' for use in `END' rules.  Be aware, however, that Unix
+`awk', and possibly other implementations, do not.
+
+   The third point follows from the first two.  What is the meaning of
+`print' inside a `BEGIN' or `END' rule?  The meaning is the same as
+always, `print $0'.  If `$0' is the null string, then this prints an
+empty line.  Many long time `awk' programmers use `print' in `BEGIN'
+and `END' rules, to mean `print ""', relying on `$0' being null.  While
+you might generally get away with this in `BEGIN' rules, in `gawk' at
+least, it is a very bad idea in `END' rules.  It is also poor style,
+since if you want an empty line in the output, you should say so
+explicitly in your program.
+
+
+File: gawk.info,  Node: Empty,  Prev: BEGIN/END,  Up: Pattern Overview
+
+The Empty Pattern
+-----------------
+
+   An empty (i.e. non-existent) pattern is considered to match _every_
+input record.  For example, the program:
+
+     awk '{ print $1 }' BBS-list
+
+prints the first field of every record.
+
+
+File: gawk.info,  Node: Action Overview,  Prev: Pattern Overview,  Up: Patterns and Actions
+
+Overview of Actions
+===================
+
+   An `awk' program or script consists of a series of rules and
+function definitions, interspersed.  (Functions are described later.
+*Note User-defined Functions: User-defined.)
+
+   A rule contains a pattern and an action, either of which (but not
+both) may be omitted.  The purpose of the "action" is to tell `awk'
+what to do once a match for the pattern is found.  Thus, in outline, an
+`awk' program generally looks like this:
+
+     [PATTERN] [{ ACTION }]
+     [PATTERN] [{ ACTION }]
+     ...
+     function NAME(ARGS) { ... }
+     ...
+
+   An action consists of one or more `awk' "statements", enclosed in
+curly braces (`{' and `}').  Each statement specifies one thing to be
+done.  The statements are separated by newlines or semicolons.
+
+   The curly braces around an action must be used even if the action
+contains only one statement, or even if it contains no statements at
+all.  However, if you omit the action entirely, omit the curly braces as
+well.  An omitted action is equivalent to `{ print $0 }'.
+
+     /foo/  { }  # match foo, do nothing - empty action
+     /foo/       # match foo, print the record - omitted action
+
+   Here are the kinds of statements supported in `awk':
+
+   * Expressions, which can call functions or assign values to variables
+     (*note Expressions::).  Executing this kind of statement simply
+     computes the value of the expression.  This is useful when the
+     expression has side effects (*note Assignment Expressions:
+     Assignment Ops.).
+
+   * Control statements, which specify the control flow of `awk'
+     programs.  The `awk' language gives you C-like constructs (`if',
+     `for', `while', and `do') as well as a few special ones (*note
+     Control Statements in Actions: Statements.).
+
+   * Compound statements, which consist of one or more statements
+     enclosed in curly braces.  A compound statement is used in order
+     to put several statements together in the body of an `if',
+     `while', `do' or `for' statement.
+
+   * Input statements, using the `getline' command (*note Explicit
+     Input with `getline': Getline.), the `next' statement (*note The
+     `next' Statement: Next Statement.), and the `nextfile' statement
+     (*note The `nextfile' Statement: Nextfile Statement.).
+
+   * Output statements, `print' and `printf'.  *Note Printing Output:
+     Printing.
+
+   * Deletion statements, for deleting array elements.  *Note The
+     `delete' Statement: Delete.
+
+
+File: gawk.info,  Node: Statements,  Next: Built-in Variables,  Prev: Patterns and Actions,  Up: Top
+
+Control Statements in Actions
+*****************************
+
+   "Control statements" such as `if', `while', and so on control the
+flow of execution in `awk' programs.  Most of the control statements in
+`awk' are patterned on similar statements in C.
+
+   All the control statements start with special keywords such as `if'
+and `while', to distinguish them from simple expressions.
+
+   Many control statements contain other statements; for example, the
+`if' statement contains another statement which may or may not be
+executed.  The contained statement is called the "body".  If you want
+to include more than one statement in the body, group them into a
+single "compound statement" with curly braces, separating them with
+newlines or semicolons.
+
+* Menu:
+
+* If Statement::                Conditionally execute some `awk'
+                                statements.
+* While Statement::             Loop until some condition is satisfied.
+* Do Statement::                Do specified action while looping until some
+                                condition is satisfied.
+* For Statement::               Another looping statement, that provides
+                                initialization and increment clauses.
+* Break Statement::             Immediately exit the innermost enclosing loop.
+* Continue Statement::          Skip to the end of the innermost enclosing
+                                loop.
+* Next Statement::              Stop processing the current input record.
+* Nextfile Statement::          Stop processing the current file.
+* Exit Statement::              Stop execution of `awk'.
+
+
+File: gawk.info,  Node: If Statement,  Next: While Statement,  Prev: Statements,  Up: Statements
+
+The `if'-`else' Statement
+=========================
+
+   The `if'-`else' statement is `awk''s decision-making statement.  It
+looks like this:
+
+     if (CONDITION) THEN-BODY [else ELSE-BODY]
+
+The CONDITION is an expression that controls what the rest of the
+statement will do.  If CONDITION is true, THEN-BODY is executed;
+otherwise, ELSE-BODY is executed.  The `else' part of the statement is
+optional.  The condition is considered false if its value is zero or
+the null string, and true otherwise.
+
+   Here is an example:
+
+     if (x % 2 == 0)
+         print "x is even"
+     else
+         print "x is odd"
+
+   In this example, if the expression `x % 2 == 0' is true (that is,
+the value of `x' is evenly divisible by two), then the first `print'
+statement is executed, otherwise the second `print' statement is
+executed.
+
+   If the `else' appears on the same line as THEN-BODY, and THEN-BODY
+is not a compound statement (i.e. not surrounded by curly braces), then
+a semicolon must separate THEN-BODY from `else'.  To illustrate this,
+let's rewrite the previous example:
+
+     if (x % 2 == 0) print "x is even"; else
+             print "x is odd"
+
+If you forget the `;', `awk' won't be able to interpret the statement,
+and you will get a syntax error.
+
+   We would not actually write this example this way, because a human
+reader might fail to see the `else' if it were not the first thing on
+its line.
+
+
+File: gawk.info,  Node: While Statement,  Next: Do Statement,  Prev: If Statement,  Up: Statements
+
+The `while' Statement
+=====================
+
+   In programming, a "loop" means a part of a program that can be
+executed two or more times in succession.
+
+   The `while' statement is the simplest looping statement in `awk'.
+It repeatedly executes a statement as long as a condition is true.  It
+looks like this:
+
+     while (CONDITION)
+       BODY
+
+Here BODY is a statement that we call the "body" of the loop, and
+CONDITION is an expression that controls how long the loop keeps
+running.
+
+   The first thing the `while' statement does is test CONDITION.  If
+CONDITION is true, it executes the statement BODY.  (The CONDITION is
+true when the value is not zero and not a null string.)  After BODY has
+been executed, CONDITION is tested again, and if it is still true, BODY
+is executed again.  This process repeats until CONDITION is no longer
+true.  If CONDITION is initially false, the body of the loop is never
+executed, and `awk' continues with the statement following the loop.
+
+   This example prints the first three fields of each record, one per
+line.
+
+     awk '{ i = 1
+            while (i <= 3) {
+                print $i
+                i++
+            }
+     }' inventory-shipped
+
+Here the body of the loop is a compound statement enclosed in braces,
+containing two statements.
+
+   The loop works like this: first, the value of `i' is set to one.
+Then, the `while' tests whether `i' is less than or equal to three.
+This is true when `i' equals one, so the `i'-th field is printed.  Then
+the `i++' increments the value of `i' and the loop repeats.  The loop
+terminates when `i' reaches four.
+
+   As you can see, a newline is not required between the condition and
+the body; but using one makes the program clearer unless the body is a
+compound statement or is very simple.  The newline after the open-brace
+that begins the compound statement is not required either, but the
+program would be harder to read without it.
+
+
+File: gawk.info,  Node: Do Statement,  Next: For Statement,  Prev: While Statement,  Up: Statements
+
+The `do'-`while' Statement
+==========================
+
+   The `do' loop is a variation of the `while' looping statement.  The
+`do' loop executes the BODY once, and then repeats BODY as long as
+CONDITION is true.  It looks like this:
+
+     do
+       BODY
+     while (CONDITION)
+
+   Even if CONDITION is false at the start, BODY is executed at least
+once (and only once, unless executing BODY makes CONDITION true).
+Contrast this with the corresponding `while' statement:
+
+     while (CONDITION)
+       BODY
+
+This statement does not execute BODY even once if CONDITION is false to
+begin with.
+
+   Here is an example of a `do' statement:
+
+     awk '{ i = 1
+            do {
+               print $0
+               i++
+            } while (i <= 10)
+     }'
+
+This program prints each input record ten times.  It isn't a very
+realistic example, since in this case an ordinary `while' would do just
+as well.  But this reflects actual experience; there is only
+occasionally a real use for a `do' statement.
+
+
+File: gawk.info,  Node: For Statement,  Next: Break Statement,  Prev: Do Statement,  Up: Statements
+
+The `for' Statement
+===================
+
+   The `for' statement makes it more convenient to count iterations of a
+loop.  The general form of the `for' statement looks like this:
+
+     for (INITIALIZATION; CONDITION; INCREMENT)
+       BODY
+
+The INITIALIZATION, CONDITION and INCREMENT parts are arbitrary `awk'
+expressions, and BODY stands for any `awk' statement.
+
+   The `for' statement starts by executing INITIALIZATION.  Then, as
+long as CONDITION is true, it repeatedly executes BODY and then
+INCREMENT.  Typically INITIALIZATION sets a variable to either zero or
+one, INCREMENT adds one to it, and CONDITION compares it against the
+desired number of iterations.
+
+   Here is an example of a `for' statement:
+
+     awk '{ for (i = 1; i <= 3; i++)
+               print $i
+     }' inventory-shipped
+
+This prints the first three fields of each input record, one field per
+line.
+
+   You cannot set more than one variable in the INITIALIZATION part
+unless you use a multiple assignment statement such as `x = y = 0',
+which is possible only if all the initial values are equal.  (But you
+can initialize additional variables by writing their assignments as
+separate statements preceding the `for' loop.)
+
+   The same is true of the INCREMENT part; to increment additional
+variables, you must write separate statements at the end of the loop.
+The C compound expression, using C's comma operator, would be useful in
+this context, but it is not supported in `awk'.
+
+   Most often, INCREMENT is an increment expression, as in the example
+above.  But this is not required; it can be any expression whatever.
+For example, this statement prints all the powers of two between one
+and 100:
+
+     for (i = 1; i <= 100; i *= 2)
+       print i
+
+   Any of the three expressions in the parentheses following the `for'
+may be omitted if there is nothing to be done there.  Thus,
+`for (; x > 0;)' is equivalent to `while (x > 0)'.  If the CONDITION is
+omitted, it is treated as TRUE, effectively yielding an "infinite loop"
+(i.e. a loop that will never terminate).
+
+   In most cases, a `for' loop is an abbreviation for a `while' loop,
+as shown here:
+
+     INITIALIZATION
+     while (CONDITION) {
+       BODY
+       INCREMENT
+     }
+
+The only exception is when the `continue' statement (*note The
+`continue' Statement: Continue Statement.) is used inside the loop;
+changing a `for' statement to a `while' statement in this way can
+change the effect of the `continue' statement inside the loop.
+
+   There is an alternate version of the `for' loop, for iterating over
+all the indices of an array:
+
+     for (i in array)
+         DO SOMETHING WITH array[i]
+
+*Note Scanning All Elements of an Array: Scanning an Array, for more
+information on this version of the `for' loop.
+
+   The `awk' language has a `for' statement in addition to a `while'
+statement because often a `for' loop is both less work to type and more
+natural to think of.  Counting the number of iterations is very common
+in loops.  It can be easier to think of this counting as part of
+looping rather than as something to do inside the loop.
+
+   The next section has more complicated examples of `for' loops.
+
+
+File: gawk.info,  Node: Break Statement,  Next: Continue Statement,  Prev: For Statement,  Up: Statements
+
+The `break' Statement
+=====================
+
+   The `break' statement jumps out of the innermost `for', `while', or
+`do' loop that encloses it.  The following example finds the smallest
+divisor of any integer, and also identifies prime numbers:
+
+     awk '# find smallest divisor of num
+          { num = $1
+            for (div = 2; div*div <= num; div++)
+              if (num % div == 0)
+                break
+            if (num % div == 0)
+              printf "Smallest divisor of %d is %d\n", num, div
+            else
+              printf "%d is prime\n", num
+          }'
+
+   When the remainder is zero in the first `if' statement, `awk'
+immediately "breaks out" of the containing `for' loop.  This means that
+`awk' proceeds immediately to the statement following the loop and
+continues processing.  (This is very different from the `exit'
+statement which stops the entire `awk' program.  *Note The `exit'
+Statement: Exit Statement.)
+
+   Here is another program equivalent to the previous one.  It
+illustrates how the CONDITION of a `for' or `while' could just as well
+be replaced with a `break' inside an `if':
+
+     awk '# find smallest divisor of num
+          { num = $1
+            for (div = 2; ; div++) {
+              if (num % div == 0) {
+                printf "Smallest divisor of %d is %d\n", num, div
+                break
+              }
+              if (div*div > num) {
+                printf "%d is prime\n", num
+                break
+              }
+            }
+     }'
+
+   As described above, the `break' statement has no meaning when used
+outside the body of a loop.  However, although it was never documented,
+historical implementations of `awk' have treated the `break' statement
+outside of a loop as if it were a `next' statement (*note The `next'
+Statement: Next Statement.).  Recent versions of Unix `awk' no longer
+allow this usage.  `gawk' will support this use of `break' only if
+`--traditional' has been specified on the command line (*note Command
+Line Options: Options.).  Otherwise, it will be treated as an error,
+since the POSIX standard specifies that `break' should only be used
+inside the body of a loop (d.c.).
+
+
+File: gawk.info,  Node: Continue Statement,  Next: Next Statement,  Prev: Break Statement,  Up: Statements
+
+The `continue' Statement
+========================
+
+   The `continue' statement, like `break', is used only inside `for',
+`while', and `do' loops.  It skips over the rest of the loop body,
+causing the next cycle around the loop to begin immediately.  Contrast
+this with `break', which jumps out of the loop altogether.
+
+   The `continue' statement in a `for' loop directs `awk' to skip the
+rest of the body of the loop, and resume execution with the
+increment-expression of the `for' statement.  The following program
+illustrates this fact:
+
+     awk 'BEGIN {
+          for (x = 0; x <= 20; x++) {
+              if (x == 5)
+                  continue
+              printf "%d ", x
+          }
+          print ""
+     }'
+
+This program prints all the numbers from zero to 20, except for five,
+for which the `printf' is skipped.  Since the increment `x++' is not
+skipped, `x' does not remain stuck at five.  Contrast the `for' loop
+above with this `while' loop:
+
+     awk 'BEGIN {
+          x = 0
+          while (x <= 20) {
+              if (x == 5)
+                  continue
+              printf "%d ", x
+              x++
+          }
+          print ""
+     }'
+
+This program loops forever once `x' gets to five.
+
+   As described above, the `continue' statement has no meaning when
+used outside the body of a loop.  However, although it was never
+documented, historical implementations of `awk' have treated the
+`continue' statement outside of a loop as if it were a `next' statement
+(*note The `next' Statement: Next Statement.).  Recent versions of Unix
+`awk' no longer allow this usage.  `gawk' will support this use of
+`continue' only if `--traditional' has been specified on the command
+line (*note Command Line Options: Options.).  Otherwise, it will be
+treated as an error, since the POSIX standard specifies that `continue'
+should only be used inside the body of a loop (d.c.).
+
+
+File: gawk.info,  Node: Next Statement,  Next: Nextfile Statement,  Prev: Continue Statement,  Up: Statements
+
+The `next' Statement
+====================
+
+   The `next' statement forces `awk' to immediately stop processing the
+current record and go on to the next record.  This means that no
+further rules are executed for the current record.  The rest of the
+current rule's action is not executed either.
+
+   Contrast this with the effect of the `getline' function (*note
+Explicit Input with `getline': Getline.).  That too causes `awk' to
+read the next record immediately, but it does not alter the flow of
+control in any way.  So the rest of the current action executes with a
+new input record.
+
+   At the highest level, `awk' program execution is a loop that reads
+an input record and then tests each rule's pattern against it.  If you
+think of this loop as a `for' statement whose body contains the rules,
+then the `next' statement is analogous to a `continue' statement: it
+skips to the end of the body of this implicit loop, and executes the
+increment (which reads another record).
+
+   For example, if your `awk' program works only on records with four
+fields, and you don't want it to fail when given bad input, you might
+use this rule near the beginning of the program:
+
+     NF != 4 {
+       err = sprintf("%s:%d: skipped: NF != 4\n", FILENAME, FNR)
+       print err > "/dev/stderr"
+       next
+     }
+
+so that the following rules will not see the bad record.  The error
+message is redirected to the standard error output stream, as error
+messages should be.  *Note Special File Names in `gawk': Special Files.
+
+   According to the POSIX standard, the behavior is undefined if the
+`next' statement is used in a `BEGIN' or `END' rule.  `gawk' will treat
+it as a syntax error.  Although POSIX permits it, some other `awk'
+implementations don't allow the `next' statement inside function bodies
+(*note User-defined Functions: User-defined.).  Just as any other
+`next' statement, a `next' inside a function body reads the next record
+and starts processing it with the first rule in the program.
+
+   If the `next' statement causes the end of the input to be reached,
+then the code in any `END' rules will be executed.  *Note The `BEGIN'
+and `END' Special Patterns: BEGIN/END.
+
+   *Caution:* Some `awk' implementations generate a run-time error if
+you use the `next' statement inside a user-defined function (*note
+User-defined Functions: User-defined.).  `gawk' does not have this
+problem.
+
+
+File: gawk.info,  Node: Nextfile Statement,  Next: Exit Statement,  Prev: Next Statement,  Up: Statements
+
+The `nextfile' Statement
+========================
+
+   `gawk' provides the `nextfile' statement, which is similar to the
+`next' statement.  However, instead of abandoning processing of the
+current record, the `nextfile' statement instructs `gawk' to stop
+processing the current data file.
+
+   Upon execution of the `nextfile' statement, `FILENAME' is updated to
+the name of the next data file listed on the command line, `FNR' is
+reset to one, `ARGIND' is incremented, and processing starts over with
+the first rule in the progam.  *Note Built-in Variables::.
+
+   If the `nextfile' statement causes the end of the input to be
+reached, then the code in any `END' rules will be executed.  *Note The
+`BEGIN' and `END' Special Patterns: BEGIN/END.
+
+   The `nextfile' statement is a `gawk' extension; it is not
+(currently) available in any other `awk' implementation.  *Note
+Implementing `nextfile' as a Function: Nextfile Function, for a
+user-defined function you can use to simulate the `nextfile' statement.
+
+   The `nextfile' statement would be useful if you have many data files
+to process, and you expect that you would not want to process every
+record in every file.  Normally, in order to move on to the next data
+file, you would have to continue scanning the unwanted records.  The
+`nextfile' statement accomplishes this much more efficiently.
+
+   *Caution:*  Versions of `gawk' prior to 3.0 used two words (`next
+file') for the `nextfile' statement.  This was changed in 3.0 to one
+word, since the treatment of `file' was inconsistent. When it appeared
+after `next', it was a keyword.  Otherwise, it was a regular
+identifier.  The old usage is still accepted. However, `gawk' will
+generate a warning message, and support for `next file' will eventually
+be discontinued in a future version of `gawk'.
+
+
+File: gawk.info,  Node: Exit Statement,  Prev: Nextfile Statement,  Up: Statements
+
+The `exit' Statement
+====================
+
+   The `exit' statement causes `awk' to immediately stop executing the
+current rule and to stop processing input; any remaining input is
+ignored.  It looks like this:
+
+     exit [RETURN CODE]
+
+   If an `exit' statement is executed from a `BEGIN' rule the program
+stops processing everything immediately.  No input records are read.
+However, if an `END' rule is present, it is executed (*note The `BEGIN'
+and `END' Special Patterns: BEGIN/END.).
+
+   If `exit' is used as part of an `END' rule, it causes the program to
+stop immediately.
+
+   An `exit' statement that is not part of a `BEGIN' or `END' rule
+stops the execution of any further automatic rules for the current
+record, skips reading any remaining input records, and executes the
+`END' rule if there is one.
+
+   If you do not want the `END' rule to do its job in this case, you
+can set a variable to non-zero before the `exit' statement, and check
+that variable in the `END' rule.  *Note Assertions: Assert Function,
+for an example that does this.
+
+   If an argument is supplied to `exit', its value is used as the exit
+status code for the `awk' process.  If no argument is supplied, `exit'
+returns status zero (success).  In the case where an argument is
+supplied to a first `exit' statement, and then `exit' is called a
+second time with no argument, the previously supplied exit value is
+used (d.c.).
+
+   For example, let's say you've discovered an error condition you
+really don't know how to handle.  Conventionally, programs report this
+by exiting with a non-zero status.  Your `awk' program can do this
+using an `exit' statement with a non-zero argument.  Here is an example:
+
+     BEGIN {
+            if (("date" | getline date_now) < 0) {
+              print "Can't get system date" > "/dev/stderr"
+              exit 1
+            }
+            print "current date is", date_now
+            close("date")
+     }
+
+
+File: gawk.info,  Node: Built-in Variables,  Next: Arrays,  Prev: Statements,  Up: Top
+
+Built-in Variables
+******************
+
+   Most `awk' variables are available for you to use for your own
+purposes; they never change except when your program assigns values to
+them, and never affect anything except when your program examines them.
+However, a few variables in `awk' have special built-in meanings.  Some
+of them `awk' examines automatically, so that they enable you to tell
+`awk' how to do certain things.  Others are set automatically by `awk',
+so that they carry information from the internal workings of `awk' to
+your program.
+
+   This chapter documents all the built-in variables of `gawk'.  Most
+of them are also documented in the chapters describing their areas of
+activity.
+
+* Menu:
+
+* User-modified::               Built-in variables that you change to control
+                                `awk'.
+* Auto-set::                    Built-in variables where `awk' gives you
+                                information.
+* ARGC and ARGV::               Ways to use `ARGC' and `ARGV'.
+
+
+File: gawk.info,  Node: User-modified,  Next: Auto-set,  Prev: Built-in Variables,  Up: Built-in Variables
+
+Built-in Variables that Control `awk'
+=====================================
+
+   This is an alphabetical list of the variables which you can change to
+control how `awk' does certain things. Those variables that are
+specific to `gawk' are marked with an asterisk, `*'.
+
+`CONVFMT'
+     This string controls conversion of numbers to strings (*note
+     Conversion of Strings and Numbers: Conversion.).  It works by
+     being passed, in effect, as the first argument to the `sprintf'
+     function (*note Built-in Functions for String Manipulation: String
+     Functions.).  Its default value is `"%.6g"'.  `CONVFMT' was
+     introduced by the POSIX standard.
+
+`FIELDWIDTHS *'
+     This is a space separated list of columns that tells `gawk' how to
+     split input with fixed, columnar boundaries.  It is an
+     experimental feature.  Assigning to `FIELDWIDTHS' overrides the
+     use of `FS' for field splitting.  *Note Reading Fixed-width Data:
+     Constant Size, for more information.
+
+     If `gawk' is in compatibility mode (*note Command Line Options:
+     Options.), then `FIELDWIDTHS' has no special meaning, and field
+     splitting operations are done based exclusively on the value of
+     `FS'.
+
+`FS'
+     `FS' is the input field separator (*note Specifying How Fields are
+     Separated: Field Separators.).  The value is a single-character
+     string or a multi-character regular expression that matches the
+     separations between fields in an input record.  If the value is
+     the null string (`""'), then each character in the record becomes
+     a separate field.
+
+     The default value is `" "', a string consisting of a single space.
+     As a special exception, this value means that any sequence of
+     spaces, tabs, and/or newlines is a single separator.(1)  It also
+     causes spaces, tabs, and newlines at the beginning and end of a
+     record to be ignored.
+
+     You can set the value of `FS' on the command line using the `-F'
+     option:
+
+          awk -F, 'PROGRAM' INPUT-FILES
+
+     If `gawk' is using `FIELDWIDTHS' for field-splitting, assigning a
+     value to `FS' will cause `gawk' to return to the normal,
+     `FS'-based, field splitting. An easy way to do this is to simply
+     say `FS = FS', perhaps with an explanatory comment.
+
+`IGNORECASE *'
+     If `IGNORECASE' is non-zero or non-null, then all string
+     comparisons, and all regular expression matching are
+     case-independent.  Thus, regexp matching with `~' and `!~', and
+     the `gensub', `gsub', `index', `match', `split' and `sub'
+     functions, record termination with `RS', and field splitting with
+     `FS' all ignore case when doing their particular regexp operations.
+     *Note Case-sensitivity in Matching: Case-sensitivity.
+
+     If `gawk' is in compatibility mode (*note Command Line Options:
+     Options.), then `IGNORECASE' has no special meaning, and string
+     and regexp operations are always case-sensitive.
+
+`OFMT'
+     This string controls conversion of numbers to strings (*note
+     Conversion of Strings and Numbers: Conversion.) for printing with
+     the `print' statement.  It works by being passed, in effect, as
+     the first argument to the `sprintf' function (*note Built-in
+     Functions for String Manipulation: String Functions.).  Its
+     default value is `"%.6g"'.  Earlier versions of `awk' also used
+     `OFMT' to specify the format for converting numbers to strings in
+     general expressions; this is now done by `CONVFMT'.
+
+`OFS'
+     This is the output field separator (*note Output Separators::).
+     It is output between the fields output by a `print' statement.  Its
+     default value is `" "', a string consisting of a single space.
+
+`ORS'
+     This is the output record separator.  It is output at the end of
+     every `print' statement.  Its default value is `"\n"'.  (*Note
+     Output Separators::.)
+
+`RS'
+     This is `awk''s input record separator.  Its default value is a
+     string containing a single newline character, which means that an
+     input record consists of a single line of text.  It can also be
+     the null string, in which case records are separated by runs of
+     blank lines, or a regexp, in which case records are separated by
+     matches of the regexp in the input text.  (*Note How Input is
+     Split into Records: Records.)
+
+`SUBSEP'
+     `SUBSEP' is the subscript separator.  It has the default value of
+     `"\034"', and is used to separate the parts of the indices of a
+     multi-dimensional array.  Thus, the expression `foo["A", "B"]'
+     really accesses `foo["A\034B"]' (*note Multi-dimensional Arrays:
+     Multi-dimensional.).
+
+   ---------- Footnotes ----------
+
+   (1) In POSIX `awk', newline does not count as whitespace.
+
+
+File: gawk.info,  Node: Auto-set,  Next: ARGC and ARGV,  Prev: User-modified,  Up: Built-in Variables
+
+Built-in Variables that Convey Information
+==========================================
+
+   This is an alphabetical list of the variables that are set
+automatically by `awk' on certain occasions in order to provide
+information to your program.  Those variables that are specific to
+`gawk' are marked with an asterisk, `*'.
+
+`ARGC'
+`ARGV'
+     The command-line arguments available to `awk' programs are stored
+     in an array called `ARGV'.  `ARGC' is the number of command-line
+     arguments present.  *Note Other Command Line Arguments: Other
+     Arguments.  Unlike most `awk' arrays, `ARGV' is indexed from zero
+     to `ARGC' - 1.  For example:
+
+          $ awk 'BEGIN {
+          >        for (i = 0; i < ARGC; i++)
+          >            print ARGV[i]
+          >      }' inventory-shipped BBS-list
+          -| awk
+          -| inventory-shipped
+          -| BBS-list
+
+     In this example, `ARGV[0]' contains `"awk"', `ARGV[1]' contains
+     `"inventory-shipped"', and `ARGV[2]' contains `"BBS-list"'.  The
+     value of `ARGC' is three, one more than the index of the last
+     element in `ARGV', since the elements are numbered from zero.
+
+     The names `ARGC' and `ARGV', as well as the convention of indexing
+     the array from zero to `ARGC' - 1, are derived from the C
+     language's method of accessing command line arguments.  *Note
+     Using `ARGC' and `ARGV': ARGC and ARGV, for information about how
+     `awk' uses these variables.
+
+`ARGIND *'
+     The index in `ARGV' of the current file being processed.  Every
+     time `gawk' opens a new data file for processing, it sets `ARGIND'
+     to the index in `ARGV' of the file name.  When `gawk' is
+     processing the input files, it is always true that `FILENAME ==
+     ARGV[ARGIND]'.
+
+     This variable is useful in file processing; it allows you to tell
+     how far along you are in the list of data files, and to
+     distinguish between successive instances of the same filename on
+     the command line.
+
+     While you can change the value of `ARGIND' within your `awk'
+     program, `gawk' will automatically set it to a new value when the
+     next file is opened.
+
+     This variable is a `gawk' extension. In other `awk'
+     implementations, or if `gawk' is in compatibility mode (*note
+     Command Line Options: Options.), it is not special.
+
+`ENVIRON'
+     An associative array that contains the values of the environment.
+     The array indices are the environment variable names; the values
+     are the values of the particular environment variables.  For
+     example, `ENVIRON["HOME"]' might be `/home/arnold'.  Changing this
+     array does not affect the environment passed on to any programs
+     that `awk' may spawn via redirection or the `system' function.
+     (In a future version of `gawk', it may do so.)
+
+     Some operating systems may not have environment variables.  On
+     such systems, the `ENVIRON' array is empty (except for
+     `ENVIRON["AWKPATH"]').
+
+`ERRNO *'
+     If a system error occurs either doing a redirection for `getline',
+     during a read for `getline', or during a `close' operation, then
+     `ERRNO' will contain a string describing the error.
+
+     This variable is a `gawk' extension. In other `awk'
+     implementations, or if `gawk' is in compatibility mode (*note
+     Command Line Options: Options.), it is not special.
+
+`FILENAME'
+     This is the name of the file that `awk' is currently reading.
+     When no data files are listed on the command line, `awk' reads
+     from the standard input, and `FILENAME' is set to `"-"'.
+     `FILENAME' is changed each time a new file is read (*note Reading
+     Input Files: Reading Files.).  Inside a `BEGIN' rule, the value of
+     `FILENAME' is `""', since there are no input files being processed
+     yet.(1) (d.c.)
+
+`FNR'
+     `FNR' is the current record number in the current file.  `FNR' is
+     incremented each time a new record is read (*note Explicit Input
+     with `getline': Getline.).  It is reinitialized to zero each time
+     a new input file is started.
+
+`NF'
+     `NF' is the number of fields in the current input record.  `NF' is
+     set each time a new record is read, when a new field is created,
+     or when `$0' changes (*note Examining Fields: Fields.).
+
+`NR'
+     This is the number of input records `awk' has processed since the
+     beginning of the program's execution (*note How Input is Split
+     into Records: Records.).  `NR' is set each time a new record is
+     read.
+
+`RLENGTH'
+     `RLENGTH' is the length of the substring matched by the `match'
+     function (*note Built-in Functions for String Manipulation: String
+     Functions.).  `RLENGTH' is set by invoking the `match' function.
+     Its value is the length of the matched string, or -1 if no match
+     was found.
+
+`RSTART'
+     `RSTART' is the start-index in characters of the substring matched
+     by the `match' function (*note Built-in Functions for String
+     Manipulation: String Functions.).  `RSTART' is set by invoking the
+     `match' function.  Its value is the position of the string where
+     the matched substring starts, or zero if no match was found.
+
+`RT *'
+     `RT' is set each time a record is read. It contains the input text
+     that matched the text denoted by `RS', the record separator.
+
+     This variable is a `gawk' extension. In other `awk'
+     implementations, or if `gawk' is in compatibility mode (*note
+     Command Line Options: Options.), it is not special.
+
+   A side note about `NR' and `FNR'.  `awk' simply increments both of
+these variables each time it reads a record, instead of setting them to
+the absolute value of the number of records read.  This means that your
+program can change these variables, and their new values will be
+incremented for each record (d.c.).  For example:
+
+     $ echo '1
+     > 2
+     > 3
+     > 4' | awk 'NR == 2 { NR = 17 }
+     > { print NR }'
+     -| 1
+     -| 17
+     -| 18
+     -| 19
+
+Before `FNR' was added to the `awk' language (*note Major Changes
+between V7 and SVR3.1: V7/SVR3.1.), many `awk' programs used this
+feature to track the number of records in a file by resetting `NR' to
+zero when `FILENAME' changed.
+
+   ---------- Footnotes ----------
+
+   (1) Some early implementations of Unix `awk' initialized `FILENAME'
+to `"-"', even if there were data files to be processed. This behavior
+was incorrect, and should not be relied upon in your programs.
+
+
+File: gawk.info,  Node: ARGC and ARGV,  Prev: Auto-set,  Up: Built-in Variables
+
+Using `ARGC' and `ARGV'
+=======================
+
+   In *Note Built-in Variables that Convey Information: Auto-set, you
+saw this program describing the information contained in `ARGC' and
+`ARGV':
+
+     $ awk 'BEGIN {
+     >        for (i = 0; i < ARGC; i++)
+     >            print ARGV[i]
+     >      }' inventory-shipped BBS-list
+     -| awk
+     -| inventory-shipped
+     -| BBS-list
+
+In this example, `ARGV[0]' contains `"awk"', `ARGV[1]' contains
+`"inventory-shipped"', and `ARGV[2]' contains `"BBS-list"'.
+
+   Notice that the `awk' program is not entered in `ARGV'.  The other
+special command line options, with their arguments, are also not
+entered.  But variable assignments on the command line _are_ treated as
+arguments, and do show up in the `ARGV' array.
+
+   Your program can alter `ARGC' and the elements of `ARGV'.  Each time
+`awk' reaches the end of an input file, it uses the next element of
+`ARGV' as the name of the next input file.  By storing a different
+string there, your program can change which files are read.  You can
+use `"-"' to represent the standard input.  By storing additional
+elements and incrementing `ARGC' you can cause additional files to be
+read.
+
+   If you decrease the value of `ARGC', that eliminates input files
+from the end of the list.  By recording the old value of `ARGC'
+elsewhere, your program can treat the eliminated arguments as something
+other than file names.
+
+   To eliminate a file from the middle of the list, store the null
+string (`""') into `ARGV' in place of the file's name.  As a special
+feature, `awk' ignores file names that have been replaced with the null
+string.  You may also use the `delete' statement to remove elements from
+`ARGV' (*note The `delete' Statement: Delete.).
+
+   All of these actions are typically done from the `BEGIN' rule,
+before actual processing of the input begins.  *Note Splitting a Large
+File Into Pieces: Split Program, and see *Note Duplicating Output Into
+Multiple Files: Tee Program, for an example of each way of removing
+elements from `ARGV'.
+
+   The following fragment processes `ARGV' in order to examine, and
+then remove, command line options.
+
+     BEGIN {
+         for (i = 1; i < ARGC; i++) {
+             if (ARGV[i] == "-v")
+                 verbose = 1
+             else if (ARGV[i] == "-d")
+                 debug = 1
+             else if (ARGV[i] ~ /^-?/) {
+                 e = sprintf("%s: unrecognized option -- %c",
+                         ARGV[0], substr(ARGV[i], 1, ,1))
+                 print e > "/dev/stderr"
+             } else
+                 break
+             delete ARGV[i]
+         }
+     }
+
+
+File: gawk.info,  Node: Arrays,  Next: Built-in,  Prev: Built-in Variables,  Up: Top
+
+Arrays in `awk'
+***************
+
+   An "array" is a table of values, called "elements".  The elements of
+an array are distinguished by their indices.  "Indices" may be either
+numbers or strings.  `awk' maintains a single set of names that may be
+used for naming variables, arrays and functions (*note User-defined
+Functions: User-defined.).  Thus, you cannot have a variable and an
+array with the same name in the same `awk' program.
+
+* Menu:
+
+* Array Intro::                 Introduction to Arrays
+* Reference to Elements::       How to examine one element of an array.
+* Assigning Elements::          How to change an element of an array.
+* Array Example::               Basic Example of an Array
+* Scanning an Array::           A variation of the `for' statement. It
+                                loops through the indices of an array's
+                                existing elements.
+* Delete::                      The `delete' statement removes an element
+                                from an array.
+* Numeric Array Subscripts::    How to use numbers as subscripts in
+                                `awk'.
+* Uninitialized Subscripts::    Using Uninitialized variables as subscripts.
+* Multi-dimensional::           Emulating multi-dimensional arrays in
+                                `awk'.
+* Multi-scanning::              Scanning multi-dimensional arrays.
+
+
+File: gawk.info,  Node: Array Intro,  Next: Reference to Elements,  Prev: Arrays,  Up: Arrays
+
+Introduction to Arrays
+======================
+
+   The `awk' language provides one-dimensional "arrays" for storing
+groups of related strings or numbers.
+
+   Every `awk' array must have a name.  Array names have the same
+syntax as variable names; any valid variable name would also be a valid
+array name.  But you cannot use one name in both ways (as an array and
+as a variable) in one `awk' program.
+
+   Arrays in `awk' superficially resemble arrays in other programming
+languages; but there are fundamental differences.  In `awk', you don't
+need to specify the size of an array before you start to use it.
+Additionally, any number or string in `awk' may be used as an array
+index, not just consecutive integers.
+
+   In most other languages, you have to "declare" an array and specify
+how many elements or components it contains.  In such languages, the
+declaration causes a contiguous block of memory to be allocated for that
+many elements.  An index in the array usually must be a positive
+integer; for example, the index zero specifies the first element in the
+array, which is actually stored at the beginning of the block of
+memory.  Index one specifies the second element, which is stored in
+memory right after the first element, and so on.  It is impossible to
+add more elements to the array, because it has room for only as many
+elements as you declared.  (Some languages allow arbitrary starting and
+ending indices, e.g., `15 .. 27', but the size of the array is still
+fixed when the array is declared.)
+
+   A contiguous array of four elements might look like this,
+conceptually, if the element values are eight, `"foo"', `""' and 30:
+
+     +---------+---------+--------+---------+
+     |    8    |  "foo"  |   ""   |    30   |    value
+     +---------+---------+--------+---------+
+          0         1         2         3        index
+
+Only the values are stored; the indices are implicit from the order of
+the values.  Eight is the value at index zero, because eight appears in
+the position with zero elements before it.
+
+   Arrays in `awk' are different: they are "associative".  This means
+that each array is a collection of pairs: an index, and its
+corresponding array element value:
+
+     Element 4     Value 30
+     Element 2     Value "foo"
+     Element 1     Value 8
+     Element 3     Value ""
+
+We have shown the pairs in jumbled order because their order is
+irrelevant.
+
+   One advantage of associative arrays is that new pairs can be added
+at any time.  For example, suppose we add to the above array a tenth
+element whose value is `"number ten"'.  The result is this:
+
+     Element 10    Value "number ten"
+     Element 4     Value 30
+     Element 2     Value "foo"
+     Element 1     Value 8
+     Element 3     Value ""
+
+Now the array is "sparse", which just means some indices are missing:
+it has elements 1-4 and 10, but doesn't have elements 5, 6, 7, 8, or 9.
+
+   Another consequence of associative arrays is that the indices don't
+have to be positive integers.  Any number, or even a string, can be an
+index.  For example, here is an array which translates words from
+English into French:
+
+     Element "dog" Value "chien"
+     Element "cat" Value "chat"
+     Element "one" Value "un"
+     Element 1     Value "un"
+
+Here we decided to translate the number one in both spelled-out and
+numeric form--thus illustrating that a single array can have both
+numbers and strings as indices.  (In fact, array subscripts are always
+strings; this is discussed in more detail in *Note Using Numbers to
+Subscript Arrays: Numeric Array Subscripts.)
+
+   When `awk' creates an array for you, e.g., with the `split' built-in
+function, that array's indices are consecutive integers starting at one.
+(*Note Built-in Functions for String Manipulation: String Functions.)
+
+
+File: gawk.info,  Node: Reference to Elements,  Next: Assigning Elements,  Prev: Array Intro,  Up: Arrays
+
+Referring to an Array Element
+=============================
+
+   The principal way of using an array is to refer to one of its
+elements.  An array reference is an expression which looks like this:
+
+     ARRAY[INDEX]
+
+Here, ARRAY is the name of an array.  The expression INDEX is the index
+of the element of the array that you want.
+
+   The value of the array reference is the current value of that array
+element.  For example, `foo[4.3]' is an expression for the element of
+array `foo' at index `4.3'.
+
+   If you refer to an array element that has no recorded value, the
+value of the reference is `""', the null string.  This includes elements
+to which you have not assigned any value, and elements that have been
+deleted (*note The `delete' Statement: Delete.).  Such a reference
+automatically creates that array element, with the null string as its
+value.  (In some cases, this is unfortunate, because it might waste
+memory inside `awk'.)
+
+   You can find out if an element exists in an array at a certain index
+with the expression:
+
+     INDEX in ARRAY
+
+This expression tests whether or not the particular index exists,
+without the side effect of creating that element if it is not present.
+The expression has the value one (true) if `ARRAY[INDEX]' exists, and
+zero (false) if it does not exist.
+
+   For example, to test whether the array `frequencies' contains the
+index `2', you could write this statement:
+
+     if (2 in frequencies)
+         print "Subscript 2 is present."
+
+   Note that this is _not_ a test of whether or not the array
+`frequencies' contains an element whose _value_ is two.  (There is no
+way to do that except to scan all the elements.)  Also, this _does not_
+create `frequencies[2]', while the following (incorrect) alternative
+would do so:
+
+     if (frequencies[2] != "")
+         print "Subscript 2 is present."
+
+
+File: gawk.info,  Node: Assigning Elements,  Next: Array Example,  Prev: Reference to Elements,  Up: Arrays
+
+Assigning Array Elements
+========================
+
+   Array elements are lvalues: they can be assigned values just like
+`awk' variables:
+
+     ARRAY[SUBSCRIPT] = VALUE
+
+Here ARRAY is the name of your array.  The expression SUBSCRIPT is the
+index of the element of the array that you want to assign a value.  The
+expression VALUE is the value you are assigning to that element of the
+array.
+
+
+File: gawk.info,  Node: Array Example,  Next: Scanning an Array,  Prev: Assigning Elements,  Up: Arrays
+
+Basic Array Example
+===================
+
+   The following program takes a list of lines, each beginning with a
+line number, and prints them out in order of line number.  The line
+numbers are not in order, however, when they are first read:  they are
+scrambled.  This program sorts the lines by making an array using the
+line numbers as subscripts.  It then prints out the lines in sorted
+order of their numbers.  It is a very simple program, and gets confused
+if it encounters repeated numbers, gaps, or lines that don't begin with
+a number.
+
+     {
+       if ($1 > max)
+         max = $1
+       arr[$1] = $0
+     }
+     
+     END {
+       for (x = 1; x <= max; x++)
+         print arr[x]
+     }
+
+   The first rule keeps track of the largest line number seen so far;
+it also stores each line into the array `arr', at an index that is the
+line's number.
+
+   The second rule runs after all the input has been read, to print out
+all the lines.
+
+   When this program is run with the following input:
+
+     5  I am the Five man
+     2  Who are you?  The new number two!
+     4  . . . And four on the floor
+     1  Who is number one?
+     3  I three you.
+
+its output is this:
+
+     1  Who is number one?
+     2  Who are you?  The new number two!
+     3  I three you.
+     4  . . . And four on the floor
+     5  I am the Five man
+
+   If a line number is repeated, the last line with a given number
+overrides the others.
+
+   Gaps in the line numbers can be handled with an easy improvement to
+the program's `END' rule:
+
+     END {
+       for (x = 1; x <= max; x++)
+         if (x in arr)
+           print arr[x]
+     }
+
+
+File: gawk.info,  Node: Scanning an Array,  Next: Delete,  Prev: Array Example,  Up: Arrays
+
+Scanning All Elements of an Array
+=================================
+
+   In programs that use arrays, you often need a loop that executes
+once for each element of an array.  In other languages, where arrays are
+contiguous and indices are limited to positive integers, this is easy:
+you can find all the valid indices by counting from the lowest index up
+to the highest.  This technique won't do the job in `awk', since any
+number or string can be an array index.  So `awk' has a special kind of
+`for' statement for scanning an array:
+
+     for (VAR in ARRAY)
+       BODY
+
+This loop executes BODY once for each index in ARRAY that your program
+has previously used, with the variable VAR set to that index.
+
+   Here is a program that uses this form of the `for' statement.  The
+first rule scans the input records and notes which words appear (at
+least once) in the input, by storing a one into the array `used' with
+the word as index.  The second rule scans the elements of `used' to
+find all the distinct words that appear in the input.  It prints each
+word that is more than 10 characters long, and also prints the number of
+such words.  *Note Built-in Functions for String Manipulation: String
+Functions, for more information on the built-in function `length'.
+
+     # Record a 1 for each word that is used at least once.
+     {
+         for (i = 1; i <= NF; i++)
+             used[$i] = 1
+     }
+     
+     # Find number of distinct words more than 10 characters long.
+     END {
+         for (x in used)
+             if (length(x) > 10) {
+                 ++num_long_words
+                 print x
+             }
+         print num_long_words, "words longer than 10 characters"
+     }
+
+*Note Generating Word Usage Counts: Word Sorting, for a more detailed
+example of this type.
+
+   The order in which elements of the array are accessed by this
+statement is determined by the internal arrangement of the array
+elements within `awk' and cannot be controlled or changed.  This can
+lead to problems if new elements are added to ARRAY by statements in
+the loop body; you cannot predict whether or not the `for' loop will
+reach them.  Similarly, changing VAR inside the loop may produce
+strange results.  It is best to avoid such things.
+
+
+File: gawk.info,  Node: Delete,  Next: Numeric Array Subscripts,  Prev: Scanning an Array,  Up: Arrays
+
+The `delete' Statement
+======================
+
+   You can remove an individual element of an array using the `delete'
+statement:
+
+     delete ARRAY[INDEX]
+
+   Once you have deleted an array element, you can no longer obtain any
+value the element once had.  It is as if you had never referred to it
+and had never given it any value.
+
+   Here is an example of deleting elements in an array:
+
+     for (i in frequencies)
+       delete frequencies[i]
+
+This example removes all the elements from the array `frequencies'.
+
+   If you delete an element, a subsequent `for' statement to scan the
+array will not report that element, and the `in' operator to check for
+the presence of that element will return zero (i.e. false):
+
+     delete foo[4]
+     if (4 in foo)
+         print "This will never be printed"
+
+   It is important to note that deleting an element is _not_ the same
+as assigning it a null value (the empty string, `""').
+
+     foo[4] = ""
+     if (4 in foo)
+       print "This is printed, even though foo[4] is empty"
+
+   It is not an error to delete an element that does not exist.
+
+   You can delete all the elements of an array with a single statement,
+by leaving off the subscript in the `delete' statement.
+
+     delete ARRAY
+
+   This ability is a `gawk' extension; it is not available in
+compatibility mode (*note Command Line Options: Options.).
+
+   Using this version of the `delete' statement is about three times
+more efficient than the equivalent loop that deletes each element one
+at a time.
+
+   The following statement provides a portable, but non-obvious way to
+clear out an array.
+
+     # thanks to Michael Brennan for pointing this out
+     split("", array)
+
+   The `split' function (*note Built-in Functions for String
+Manipulation: String Functions.)  clears out the target array first.
+This call asks it to split apart the null string. Since there is no
+data to split out, the function simply clears the array and then
+returns.
+
+
+File: gawk.info,  Node: Numeric Array Subscripts,  Next: Uninitialized Subscripts,  Prev: Delete,  Up: Arrays
+
+Using Numbers to Subscript Arrays
+=================================
+
+   An important aspect of arrays to remember is that _array subscripts
+are always strings_.  If you use a numeric value as a subscript, it
+will be converted to a string value before it is used for subscripting
+(*note Conversion of Strings and Numbers: Conversion.).
+
+   This means that the value of the built-in variable `CONVFMT' can
+potentially affect how your program accesses elements of an array.  For
+example:
+
+     xyz = 12.153
+     data[xyz] = 1
+     CONVFMT = "%2.2f"
+     if (xyz in data)
+         printf "%s is in data\n", xyz
+     else
+         printf "%s is not in data\n", xyz
+
+This prints `12.15 is not in data'.  The first statement gives `xyz' a
+numeric value.  Assigning to `data[xyz]' subscripts `data' with the
+string value `"12.153"' (using the default conversion value of
+`CONVFMT', `"%.6g"'), and assigns one to `data["12.153"]'.  The program
+then changes the value of `CONVFMT'.  The test `(xyz in data)'
+generates a new string value from `xyz', this time `"12.15"', since the
+value of `CONVFMT' only allows two significant digits.  This test fails,
+since `"12.15"' is a different string from `"12.153"'.
+
+   According to the rules for conversions (*note Conversion of Strings
+and Numbers: Conversion.), integer values are always converted to
+strings as integers, no matter what the value of `CONVFMT' may happen
+to be.  So the usual case of:
+
+     for (i = 1; i <= maxsub; i++)
+         do something with array[i]
+
+will work, no matter what the value of `CONVFMT'.
+
+   Like many things in `awk', the majority of the time things work as
+you would expect them to work.  But it is useful to have a precise
+knowledge of the actual rules, since sometimes they can have a subtle
+effect on your programs.
+
+
+File: gawk.info,  Node: Uninitialized Subscripts,  Next: Multi-dimensional,  Prev: Numeric Array Subscripts,  Up: Arrays
+
+Using Uninitialized Variables as Subscripts
+===========================================
+
+   Suppose you want to print your input data in reverse order.  A
+reasonable attempt at a program to do so (with some test data) might
+look like this:
+
+     $ echo 'line 1
+     > line 2
+     > line 3' | awk '{ l[lines] = $0; ++lines }
+     > END {
+     >     for (i = lines-1; i >= 0; --i)
+     >        print l[i]
+     > }'
+     -| line 3
+     -| line 2
+
+   Unfortunately, the very first line of input data did not come out in
+the output!
+
+   At first glance, this program should have worked.  The variable
+`lines' is uninitialized, and uninitialized variables have the numeric
+value zero.  So, the value of `l[0]' should have been printed.
+
+   The issue here is that subscripts for `awk' arrays are *always*
+strings. And uninitialized variables, when used as strings, have the
+value `""', not zero.  Thus, `line 1' ended up stored in `l[""]'.
+
+   The following version of the program works correctly:
+
+     { l[lines++] = $0 }
+     END {
+         for (i = lines - 1; i >= 0; --i)
+            print l[i]
+     }
+
+   Here, the `++' forces `l' to be numeric, thus making the "old value"
+numeric zero, which is then converted to `"0"' as the array subscript.
+
+   As we have just seen, even though it is somewhat unusual, the null
+string (`""') is a valid array subscript (d.c.). If `--lint' is provided
+on the command line (*note Command Line Options: Options.), `gawk' will
+warn about the use of the null string as a subscript.
+
+
+File: gawk.info,  Node: Multi-dimensional,  Next: Multi-scanning,  Prev: Uninitialized Subscripts,  Up: Arrays
+
+Multi-dimensional Arrays
+========================
+
+   A multi-dimensional array is an array in which an element is
+identified by a sequence of indices, instead of a single index.  For
+example, a two-dimensional array requires two indices.  The usual way
+(in most languages, including `awk') to refer to an element of a
+two-dimensional array named `grid' is with `grid[X,Y]'.
+
+   Multi-dimensional arrays are supported in `awk' through
+concatenation of indices into one string.  What happens is that `awk'
+converts the indices into strings (*note Conversion of Strings and
+Numbers: Conversion.) and concatenates them together, with a separator
+between them.  This creates a single string that describes the values
+of the separate indices.  The combined string is used as a single index
+into an ordinary, one-dimensional array.  The separator used is the
+value of the built-in variable `SUBSEP'.
+
+   For example, suppose we evaluate the expression `foo[5,12] = "value"'
+when the value of `SUBSEP' is `"@"'.  The numbers five and 12 are
+converted to strings and concatenated with an `@' between them,
+yielding `"5@12"'; thus, the array element `foo["5@12"]' is set to
+`"value"'.
+
+   Once the element's value is stored, `awk' has no record of whether
+it was stored with a single index or a sequence of indices.  The two
+expressions `foo[5,12]' and `foo[5 SUBSEP 12]' are always equivalent.
+
+   The default value of `SUBSEP' is the string `"\034"', which contains
+a non-printing character that is unlikely to appear in an `awk' program
+or in most input data.
+
+   The usefulness of choosing an unlikely character comes from the fact
+that index values that contain a string matching `SUBSEP' lead to
+combined strings that are ambiguous.  Suppose that `SUBSEP' were `"@"';
+then `foo["a@b", "c"]' and `foo["a", "b@c"]' would be indistinguishable
+because both would actually be stored as `foo["a@b@c"]'.
+
+   You can test whether a particular index-sequence exists in a
+"multi-dimensional" array with the same operator `in' used for single
+dimensional arrays.  Instead of a single index as the left-hand operand,
+write the whole sequence of indices, separated by commas, in
+parentheses:
+
+     (SUBSCRIPT1, SUBSCRIPT2, ...) in ARRAY
+
+   The following example treats its input as a two-dimensional array of
+fields; it rotates this array 90 degrees clockwise and prints the
+result.  It assumes that all lines have the same number of elements.
+
+     awk '{
+          if (max_nf < NF)
+               max_nf = NF
+          max_nr = NR
+          for (x = 1; x <= NF; x++)
+               vector[x, NR] = $x
+     }
+     
+     END {
+          for (x = 1; x <= max_nf; x++) {
+               for (y = max_nr; y >= 1; --y)
+                    printf("%s ", vector[x, y])
+               printf("\n")
+          }
+     }'
+
+When given the input:
+
+     1 2 3 4 5 6
+     2 3 4 5 6 1
+     3 4 5 6 1 2
+     4 5 6 1 2 3
+
+it produces:
+
+     4 3 2 1
+     5 4 3 2
+     6 5 4 3
+     1 6 5 4
+     2 1 6 5
+     3 2 1 6
+
+
+File: gawk.info,  Node: Multi-scanning,  Prev: Multi-dimensional,  Up: Arrays
+
+Scanning Multi-dimensional Arrays
+=================================
+
+   There is no special `for' statement for scanning a
+"multi-dimensional" array; there cannot be one, because in truth there
+are no multi-dimensional arrays or elements; there is only a
+multi-dimensional _way of accessing_ an array.
+
+   However, if your program has an array that is always accessed as
+multi-dimensional, you can get the effect of scanning it by combining
+the scanning `for' statement (*note Scanning All Elements of an Array:
+Scanning an Array.) with the `split' built-in function (*note Built-in
+Functions for String Manipulation: String Functions.).  It works like
+this:
+
+     for (combined in array) {
+       split(combined, separate, SUBSEP)
+       ...
+     }
+
+This sets `combined' to each concatenated, combined index in the array,
+and splits it into the individual indices by breaking it apart where
+the value of `SUBSEP' appears.  The split-out indices become the
+elements of the array `separate'.
+
+   Thus, suppose you have previously stored a value in `array[1,
+"foo"]'; then an element with index `"1\034foo"' exists in `array'.
+(Recall that the default value of `SUBSEP' is the character with code
+034.)  Sooner or later the `for' statement will find that index and do
+an iteration with `combined' set to `"1\034foo"'.  Then the `split'
+function is called as follows:
+
+     split("1\034foo", separate, "\034")
+
+The result of this is to set `separate[1]' to `"1"' and `separate[2]'
+to `"foo"'.  Presto, the original sequence of separate indices has been
+recovered.
+
+
+File: gawk.info,  Node: Built-in,  Next: User-defined,  Prev: Arrays,  Up: Top
+
+Built-in Functions
+******************
+
+   "Built-in" functions are functions that are always available for
+your `awk' program to call.  This chapter defines all the built-in
+functions in `awk'; some of them are mentioned in other sections, but
+they are summarized here for your convenience.  (You can also define
+new functions yourself.  *Note User-defined Functions: User-defined.)
+
+* Menu:
+
+* Calling Built-in::            How to call built-in functions.
+* Numeric Functions::           Functions that work with numbers, including
+                                `int', `sin' and `rand'.
+* String Functions::            Functions for string manipulation, such as
+                                `split', `match', and
+                                `sprintf'.
+* I/O Functions::               Functions for files and shell commands.
+* Time Functions::              Functions for dealing with time stamps.
+
+
+File: gawk.info,  Node: Calling Built-in,  Next: Numeric Functions,  Prev: Built-in,  Up: Built-in
+
+Calling Built-in Functions
+==========================
+
+   To call a built-in function, write the name of the function followed
+by arguments in parentheses.  For example, `atan2(y + z, 1)' is a call
+to the function `atan2', with two arguments.
+
+   Whitespace is ignored between the built-in function name and the
+open-parenthesis, but we recommend that you avoid using whitespace
+there.  User-defined functions do not permit whitespace in this way, and
+you will find it easier to avoid mistakes by following a simple
+convention which always works: no whitespace after a function name.
+
+   Each built-in function accepts a certain number of arguments.  In
+some cases, arguments can be omitted. The defaults for omitted
+arguments vary from function to function and are described under the
+individual functions.  In some `awk' implementations, extra arguments
+given to built-in functions are ignored.  However, in `gawk', it is a
+fatal error to give extra arguments to a built-in function.
+
+   When a function is called, expressions that create the function's
+actual parameters are evaluated completely before the function call is
+performed.  For example, in the code fragment:
+
+     i = 4
+     j = sqrt(i++)
+
+the variable `i' is set to five before `sqrt' is called with a value of
+four for its actual parameter.
+
+   The order of evaluation of the expressions used for the function's
+parameters is undefined.  Thus, you should not write programs that
+assume that parameters are evaluated from left to right or from right
+to left.  For example,
+
+     i = 5
+     j = atan2(i++, i *= 2)
+
+   If the order of evaluation is left to right, then `i' first becomes
+six, and then 12, and `atan2' is called with the two arguments six and
+12.  But if the order of evaluation is right to left, `i' first becomes
+10, and then 11, and `atan2' is called with the two arguments 11 and 10.
+
+
+File: gawk.info,  Node: Numeric Functions,  Next: String Functions,  Prev: Calling Built-in,  Up: Built-in
+
+Numeric Built-in Functions
+==========================
+
+   Here is a full list of built-in functions that work with numbers.
+Optional parameters are enclosed in square brackets ("[" and "]").
+
+`int(X)'
+     This produces the nearest integer to X, located between X and zero,
+     truncated toward zero.
+
+     For example, `int(3)' is three, `int(3.9)' is three, `int(-3.9)'
+     is -3, and `int(-3)' is -3 as well.
+
+`sqrt(X)'
+     This gives you the positive square root of X.  It reports an error
+     if X is negative.  Thus, `sqrt(4)' is two.
+
+`exp(X)'
+     This gives you the exponential of X (`e ^ X'), or reports an error
+     if X is out of range.  The range of values X can have depends on
+     your machine's floating point representation.
+
+`log(X)'
+     This gives you the natural logarithm of X, if X is positive;
+     otherwise, it reports an error.
+
+`sin(X)'
+     This gives you the sine of X, with X in radians.
+
+`cos(X)'
+     This gives you the cosine of X, with X in radians.
+
+`atan2(Y, X)'
+     This gives you the arctangent of `Y / X' in radians.
+
+`rand()'
+     This gives you a random number.  The values of `rand' are
+     uniformly-distributed between zero and one.  The value is never
+     zero and never one.
+
+     Often you want random integers instead.  Here is a user-defined
+     function you can use to obtain a random non-negative integer less
+     than N:
+
+          function randint(n) {
+               return int(n * rand())
+          }
+
+     The multiplication produces a random real number greater than zero
+     and less than `n'.  We then make it an integer (using `int')
+     between zero and `n' - 1, inclusive.
+
+     Here is an example where a similar function is used to produce
+     random integers between one and N.  This program prints a new
+     random number for each input record.
+
+          awk '
+          # Function to roll a simulated die.
+          function roll(n) { return 1 + int(rand() * n) }
+          
+          # Roll 3 six-sided dice and
+          # print total number of points.
+          {
+                printf("%d points\n",
+                       roll(6)+roll(6)+roll(6))
+          }'
+
+     *Caution:* In most `awk' implementations, including `gawk', `rand'
+     starts generating numbers from the same starting number, or
+     "seed", each time you run `awk'.  Thus, a program will generate
+     the same results each time you run it.  The numbers are random
+     within one `awk' run, but predictable from run to run.  This is
+     convenient for debugging, but if you want a program to do
+     different things each time it is used, you must change the seed to
+     a value that will be different in each run.  To do this, use
+     `srand'.
+
+`srand([X])'
+     The function `srand' sets the starting point, or seed, for
+     generating random numbers to the value X.
+
+     Each seed value leads to a particular sequence of random
+     numbers.(1) Thus, if you set the seed to the same value a second
+     time, you will get the same sequence of random numbers again.
+
+     If you omit the argument X, as in `srand()', then the current date
+     and time of day are used for a seed.  This is the way to get random
+     numbers that are truly unpredictable.
+
+     The return value of `srand' is the previous seed.  This makes it
+     easy to keep track of the seeds for use in consistently reproducing
+     sequences of random numbers.
+
+   ---------- Footnotes ----------
+
+   (1) Computer generated random numbers really are not truly random.
+They are technically known as "pseudo-random."  This means that while
+the numbers in a sequence appear to be random, you can in fact generate
+the same sequence of random numbers over and over again.
+
+
+File: gawk.info,  Node: String Functions,  Next: I/O Functions,  Prev: Numeric Functions,  Up: Built-in
+
+Built-in Functions for String Manipulation
+==========================================
+
+   The functions in this section look at or change the text of one or
+more strings.  Optional parameters are enclosed in square brackets ("["
+and "]").
+
+`index(IN, FIND)'
+     This searches the string IN for the first occurrence of the string
+     FIND, and returns the position in characters where that occurrence
+     begins in the string IN.  For example:
+
+          $ awk 'BEGIN { print index("peanut", "an") }'
+          -| 3
+
+     If FIND is not found, `index' returns zero.  (Remember that string
+     indices in `awk' start at one.)
+
+`length([STRING])'
+     This gives you the number of characters in STRING.  If STRING is a
+     number, the length of the digit string representing that number is
+     returned.  For example, `length("abcde")' is five.  By contrast,
+     `length(15 * 35)' works out to three.  How?  Well, 15 * 35 = 525,
+     and 525 is then converted to the string `"525"', which has three
+     characters.
+
+     If no argument is supplied, `length' returns the length of `$0'.
+
+     In older versions of `awk', you could call the `length' function
+     without any parentheses.  Doing so is marked as "deprecated" in the
+     POSIX standard.  This means that while you can do this in your
+     programs, it is a feature that can eventually be removed from a
+     future version of the standard.  Therefore, for maximal
+     portability of your `awk' programs, you should always supply the
+     parentheses.
+
+`match(STRING, REGEXP)'
+     The `match' function searches the string, STRING, for the longest,
+     leftmost substring matched by the regular expression, REGEXP.  It
+     returns the character position, or "index", of where that
+     substring begins (one, if it starts at the beginning of STRING).
+     If no match is found, it returns zero.
+
+     The `match' function sets the built-in variable `RSTART' to the
+     index.  It also sets the built-in variable `RLENGTH' to the length
+     in characters of the matched substring.  If no match is found,
+     `RSTART' is set to zero, and `RLENGTH' to -1.
+
+     For example:
+
+          awk '{
+                 if ($1 == "FIND")
+                   regex = $2
+                 else {
+                   where = match($0, regex)
+                   if (where != 0)
+                     print "Match of", regex, "found at", \
+                               where, "in", $0
+                 }
+          }'
+
+     This program looks for lines that match the regular expression
+     stored in the variable `regex'.  This regular expression can be
+     changed.  If the first word on a line is `FIND', `regex' is
+     changed to be the second word on that line.  Therefore, given:
+
+          FIND ru+n
+          My program runs
+          but not very quickly
+          FIND Melvin
+          JF+KM
+          This line is property of Reality Engineering Co.
+          Melvin was here.
+
+     `awk' prints:
+
+          Match of ru+n found at 12 in My program runs
+          Match of Melvin found at 1 in Melvin was here.
+
+`split(STRING, ARRAY [, FIELDSEP])'
+     This divides STRING into pieces separated by FIELDSEP, and stores
+     the pieces in ARRAY.  The first piece is stored in `ARRAY[1]', the
+     second piece in `ARRAY[2]', and so forth.  The string value of the
+     third argument, FIELDSEP, is a regexp describing where to split
+     STRING (much as `FS' can be a regexp describing where to split
+     input records).  If the FIELDSEP is omitted, the value of `FS' is
+     used.  `split' returns the number of elements created.
+
+     The `split' function splits strings into pieces in a manner
+     similar to the way input lines are split into fields.  For example:
+
+          split("cul-de-sac", a, "-")
+
+     splits the string `cul-de-sac' into three fields using `-' as the
+     separator.  It sets the contents of the array `a' as follows:
+
+          a[1] = "cul"
+          a[2] = "de"
+          a[3] = "sac"
+
+     The value returned by this call to `split' is three.
+
+     As with input field-splitting, when the value of FIELDSEP is
+     `" "', leading and trailing whitespace is ignored, and the elements
+     are separated by runs of whitespace.
+
+     Also as with input field-splitting, if FIELDSEP is the null
+     string, each individual character in the string is split into its
+     own array element.  (This is a `gawk'-specific extension.)
+
+     Recent implementations of `awk', including `gawk', allow the third
+     argument to be a regexp constant (`/abc/'), as well as a string
+     (d.c.).  The POSIX standard allows this as well.
+
+     Before splitting the string, `split' deletes any previously
+     existing elements in the array ARRAY (d.c.).
+
+`sprintf(FORMAT, EXPRESSION1,...)'
+     This returns (without printing) the string that `printf' would
+     have printed out with the same arguments (*note Using `printf'
+     Statements for Fancier Printing: Printf.).  For example:
+
+          sprintf("pi = %.2f (approx.)", 22/7)
+
+     returns the string `"pi = 3.14 (approx.)"'.
+
+`sub(REGEXP, REPLACEMENT [, TARGET])'
+     The `sub' function alters the value of TARGET.  It searches this
+     value, which is treated as a string, for the leftmost longest
+     substring matched by the regular expression, REGEXP, extending
+     this match as far as possible.  Then the entire string is changed
+     by replacing the matched text with REPLACEMENT.  The modified
+     string becomes the new value of TARGET.
+
+     This function is peculiar because TARGET is not simply used to
+     compute a value, and not just any expression will do: it must be a
+     variable, field or array element, so that `sub' can store a
+     modified value there.  If this argument is omitted, then the
+     default is to use and alter `$0'.
+
+     For example:
+
+          str = "water, water, everywhere"
+          sub(/at/, "ith", str)
+
+     sets `str' to `"wither, water, everywhere"', by replacing the
+     leftmost, longest occurrence of `at' with `ith'.
+
+     The `sub' function returns the number of substitutions made (either
+     one or zero).
+
+     If the special character `&' appears in REPLACEMENT, it stands for
+     the precise substring that was matched by REGEXP.  (If the regexp
+     can match more than one string, then this precise substring may
+     vary.)  For example:
+
+          awk '{ sub(/candidate/, "& and his wife"); print }'
+
+     changes the first occurrence of `candidate' to `candidate and his
+     wife' on each input line.
+
+     Here is another example:
+
+          awk 'BEGIN {
+                  str = "daabaaa"
+                  sub(/a*/, "c&c", str)
+                  print str
+          }'
+          -| dcaacbaaa
+
+     This shows how `&' can represent a non-constant string, and also
+     illustrates the "leftmost, longest" rule in regexp matching (*note
+     How Much Text Matches?: Leftmost Longest.).
+
+     The effect of this special character (`&') can be turned off by
+     putting a backslash before it in the string.  As usual, to insert
+     one backslash in the string, you must write two backslashes.
+     Therefore, write `\\&' in a string constant to include a literal
+     `&' in the replacement.  For example, here is how to replace the
+     first `|' on each line with an `&':
+
+          awk '{ sub(/\|/, "\\&"); print }'
+
+     *Note:* As mentioned above, the third argument to `sub' must be a
+     variable, field or array reference.  Some versions of `awk' allow
+     the third argument to be an expression which is not an lvalue.  In
+     such a case, `sub' would still search for the pattern and return
+     zero or one, but the result of the substitution (if any) would be
+     thrown away because there is no place to put it.  Such versions of
+     `awk' accept expressions like this:
+
+          sub(/USA/, "United States", "the USA and Canada")
+
+     For historical compatibility, `gawk' will accept erroneous code,
+     such as in the above example. However, using any other
+     non-changeable object as the third parameter will cause a fatal
+     error, and your program will not run.
+
+`gsub(REGEXP, REPLACEMENT [, TARGET])'
+     This is similar to the `sub' function, except `gsub' replaces
+     _all_ of the longest, leftmost, _non-overlapping_ matching
+     substrings it can find.  The `g' in `gsub' stands for "global,"
+     which means replace everywhere.  For example:
+
+          awk '{ gsub(/Britain/, "United Kingdom"); print }'
+
+     replaces all occurrences of the string `Britain' with `United
+     Kingdom' for all input records.
+
+     The `gsub' function returns the number of substitutions made.  If
+     the variable to be searched and altered, TARGET, is omitted, then
+     the entire input record, `$0', is used.
+
+     As in `sub', the characters `&' and `\' are special, and the third
+     argument must be an lvalue.
+
+`gensub(REGEXP, REPLACEMENT, HOW [, TARGET])'
+     `gensub' is a general substitution function.  Like `sub' and
+     `gsub', it searches the target string TARGET for matches of the
+     regular expression REGEXP.  Unlike `sub' and `gsub', the modified
+     string is returned as the result of the function, and the original
+     target string is _not_ changed.  If HOW is a string beginning with
+     `g' or `G', then it replaces all matches of REGEXP with
+     REPLACEMENT.  Otherwise, HOW is a number indicating which match of
+     REGEXP to replace. If no TARGET is supplied, `$0' is used instead.
+
+     `gensub' provides an additional feature that is not available in
+     `sub' or `gsub': the ability to specify components of a regexp in
+     the replacement text.  This is done by using parentheses in the
+     regexp to mark the components, and then specifying `\N' in the
+     replacement text, where N is a digit from one to nine.  For
+     example:
+
+          $ gawk '
+          > BEGIN {
+          >      a = "abc def"
+          >      b = gensub(/(.+) (.+)/, "\\2 \\1", "g", a)
+          >      print b
+          > }'
+          -| def abc
+
+     As described above for `sub', you must type two backslashes in
+     order to get one into the string.
+
+     In the replacement text, the sequence `\0' represents the entire
+     matched text, as does the character `&'.
+
+     This example shows how you can use the third argument to control
+     which match of the regexp should be changed.
+
+          $ echo a b c a b c |
+          > gawk '{ print gensub(/a/, "AA", 2) }'
+          -| a b c AA b c
+
+     In this case, `$0' is used as the default target string.  `gensub'
+     returns the new string as its result, which is passed directly to
+     `print' for printing.
+
+     If the HOW argument is a string that does not begin with `g' or
+     `G', or if it is a number that is less than zero, only one
+     substitution is performed.
+
+     `gensub' is a `gawk' extension; it is not available in
+     compatibility mode (*note Command Line Options: Options.).
+
+`substr(STRING, START [, LENGTH])'
+     This returns a LENGTH-character-long substring of STRING, starting
+     at character number START.  The first character of a string is
+     character number one.  For example, `substr("washington", 5, 3)'
+     returns `"ing"'.
+
+     If LENGTH is not present, this function returns the whole suffix of
+     STRING that begins at character number START.  For example,
+     `substr("washington", 5)' returns `"ington"'.  The whole suffix is
+     also returned if LENGTH is greater than the number of characters
+     remaining in the string, counting from character number START.
+
+     *Note:* The string returned by `substr' _cannot_ be assigned to.
+     Thus, it is a mistake to attempt to change a portion of a string,
+     like this:
+
+          string = "abcdef"
+          # try to get "abCDEf", won't work
+          substr(string, 3, 3) = "CDE"
+
+     or to use `substr' as the third agument of `sub' or `gsub':
+
+          gsub(/xyz/, "pdq", substr($0, 5, 20))  # WRONG
+
+`tolower(STRING)'
+     This returns a copy of STRING, with each upper-case character in
+     the string replaced with its corresponding lower-case character.
+     Non-alphabetic characters are left unchanged.  For example,
+     `tolower("MiXeD cAsE 123")' returns `"mixed case 123"'.
+
+`toupper(STRING)'
+     This returns a copy of STRING, with each lower-case character in
+     the string replaced with its corresponding upper-case character.
+     Non-alphabetic characters are left unchanged.  For example,
+     `toupper("MiXeD cAsE 123")' returns `"MIXED CASE 123"'.
+
+More About `\' and `&' with `sub', `gsub' and `gensub'
+------------------------------------------------------
+
+   When using `sub', `gsub' or `gensub', and trying to get literal
+backslashes and ampersands into the replacement text, you need to
+remember that there are several levels of "escape processing" going on.
+
+   First, there is the "lexical" level, which is when `awk' reads your
+program, and builds an internal copy of your program that can be
+executed.
+
+   Then there is the run-time level, when `awk' actually scans the
+replacement string to determine what to generate.
+
+   At both levels, `awk' looks for a defined set of characters that can
+come after a backslash.  At the lexical level, it looks for the escape
+sequences listed in *Note Escape Sequences::.  Thus, for every `\' that
+`awk' will process at the run-time level, you type two `\'s at the
+lexical level.  When a character that is not valid for an escape
+sequence follows the `\', Unix `awk' and `gawk' both simply remove the
+initial `\', and put the following character into the string. Thus, for
+example, `"a\qb"' is treated as `"aqb"'.
+
+   At the run-time level, the various functions handle sequences of `\'
+and `&' differently.  The situation is (sadly) somewhat complex.
+
+   Historically, the `sub' and `gsub' functions treated the two
+character sequence `\&' specially; this sequence was replaced in the
+generated text with a single `&'.  Any other `\' within the REPLACEMENT
+string that did not precede an `&' was passed through unchanged.  To
+illustrate with a table:
+
+      You type         `sub' sees          `sub' generates
+      --------         ----------          ---------------
+          `\&'              `&'            the matched text
+         `\\&'             `\&'            a literal `&'
+        `\\\&'             `\&'            a literal `&'
+       `\\\\&'            `\\&'            a literal `\&'
+      `\\\\\&'            `\\&'            a literal `\&'
+     `\\\\\\&'           `\\\&'            a literal `\\&'
+         `\\q'             `\q'            a literal `\q'
+
+This table shows both the lexical level processing, where an odd number
+of backslashes becomes an even number at the run time level, and the
+run-time processing done by `sub'.  (For the sake of simplicity, the
+rest of the tables below only show the case of even numbers of `\'s
+entered at the lexical level.)
+
+   The problem with the historical approach is that there is no way to
+get a literal `\' followed by the matched text.
+
+   The 1992 POSIX standard attempted to fix this problem. The standard
+says that `sub' and `gsub' look for either a `\' or an `&' after the
+`\'. If either one follows a `\', that character is output literally.
+The interpretation of `\' and `&' then becomes like this:
+
+      You type         `sub' sees          `sub' generates
+      --------         ----------          ---------------
+           `&'              `&'            the matched text
+         `\\&'             `\&'            a literal `&'
+       `\\\\&'            `\\&'            a literal `\', then the matched text
+     `\\\\\\&'           `\\\&'            a literal `\&'
+
+This would appear to solve the problem.  Unfortunately, the phrasing of
+the standard is unusual. It says, in effect, that `\' turns off the
+special meaning of any following character, but that for anything other
+than `\' and `&', such special meaning is undefined.  This wording
+leads to two problems.
+
+  1. Backslashes must now be doubled in the REPLACEMENT string, breaking
+     historical `awk' programs.
+
+  2. To make sure that an `awk' program is portable, _every_ character
+     in the REPLACEMENT string must be preceded with a backslash.(1)
+
+   The POSIX standard is under revision.(2) Because of the above
+problems, proposed text for the revised standard reverts to rules that
+correspond more closely to the original existing practice. The proposed
+rules have special cases that make it possible to produce a `\'
+preceding the matched text.
+
+      You type         `sub' sees         `sub' generates
+      --------         ----------         ---------------
+     `\\\\\\&'           `\\\&'            a literal `\&'
+       `\\\\&'            `\\&'            a literal `\', followed by the matched text
+         `\\&'             `\&'            a literal `&'
+         `\\q'             `\q'            a literal `\q'
+
+   In a nutshell, at the run-time level, there are now three special
+sequences of characters, `\\\&', `\\&' and `\&', whereas historically,
+there was only one.  However, as in the historical case, any `\' that
+is not part of one of these three sequences is not special, and appears
+in the output literally.
+
+   `gawk' 3.0 follows these proposed POSIX rules for `sub' and `gsub'.
+Whether these proposed rules will actually become codified into the
+standard is unknown at this point. Subsequent `gawk' releases will
+track the standard and implement whatever the final version specifies;
+this Info file will be updated as well.
+
+   The rules for `gensub' are considerably simpler. At the run-time
+level, whenever `gawk' sees a `\', if the following character is a
+digit, then the text that matched the corresponding parenthesized
+subexpression is placed in the generated output.  Otherwise, no matter
+what the character after the `\' is, that character will appear in the
+generated text, and the `\' will not.
+
+       You type          `gensub' sees         `gensub' generates
+       --------          -------------         ------------------
+           `&'                    `&'            the matched text
+         `\\&'                   `\&'            a literal `&'
+        `\\\\'                   `\\'            a literal `\'
+       `\\\\&'                  `\\&'            a literal `\', then the matched text
+     `\\\\\\&'                 `\\\&'            a literal `\&'
+         `\\q'                   `\q'            a literal `q'
+
+   Because of the complexity of the lexical and run-time level
+processing, and the special cases for `sub' and `gsub', we recommend
+the use of `gawk' and `gensub' for when you have to do substitutions.
+
+   ---------- Footnotes ----------
+
+   (1) This consequence was certainly unintended.
+
+   (2) As of December 1995, with final approval and publication
+hopefully sometime in 1996.
+
+
+File: gawk.info,  Node: I/O Functions,  Next: Time Functions,  Prev: String Functions,  Up: Built-in
+
+Built-in Functions for Input/Output
+===================================
+
+   The following functions are related to Input/Output (I/O).  Optional
+parameters are enclosed in square brackets ("[" and "]").
+
+`close(FILENAME)'
+     Close the file FILENAME, for input or output.  The argument may
+     alternatively be a shell command that was used for redirecting to
+     or from a pipe; then the pipe is closed.  *Note Closing Input and
+     Output Files and Pipes: Close Files And Pipes, for more
+     information.
+
+`fflush([FILENAME])'
+     Flush any buffered output associated FILENAME, which is either a
+     file opened for writing, or a shell command for redirecting output
+     to a pipe.
+
+     Many utility programs will "buffer" their output; they save
+     information to be written to a disk file or terminal in memory,
+     until there is enough for it to be worthwhile to send the data to
+     the ouput device.  This is often more efficient than writing every
+     little bit of information as soon as it is ready.  However,
+     sometimes it is necessary to force a program to "flush" its
+     buffers; that is, write the information to its destination, even
+     if a buffer is not full.  This is the purpose of the `fflush'
+     function; `gawk' too buffers its output, and the `fflush' function
+     can be used to force `gawk' to flush its buffers.
+
+     `fflush' is a recent (1994) addition to the Bell Labs research
+     version of `awk'; it is not part of the POSIX standard, and will
+     not be available if `--posix' has been specified on the command
+     line (*note Command Line Options: Options.).
+
+     `gawk' extends the `fflush' function in two ways.  The first is to
+     allow no argument at all. In this case, the buffer for the
+     standard output is flushed.  The second way is to allow the null
+     string (`""') as the argument. In this case, the buffers for _all_
+     open output files and pipes are flushed.
+
+     `fflush' returns zero if the buffer was successfully flushed, and
+     nonzero otherwise.
+
+`system(COMMAND)'
+     The system function allows the user to execute operating system
+     commands and then return to the `awk' program.  The `system'
+     function executes the command given by the string COMMAND.  It
+     returns, as its value, the status returned by the command that was
+     executed.
+
+     For example, if the following fragment of code is put in your `awk'
+     program:
+
+          END {
+               system("date | mail -s 'awk run done' root")
+          }
+
+     the system administrator will be sent mail when the `awk' program
+     finishes processing input and begins its end-of-input processing.
+
+     Note that redirecting `print' or `printf' into a pipe is often
+     enough to accomplish your task.  However, if your `awk' program is
+     interactive, `system' is useful for cranking up large
+     self-contained programs, such as a shell or an editor.
+
+     Some operating systems cannot implement the `system' function.
+     `system' causes a fatal error if it is not supported.
+
+Interactive vs. Non-Interactive Buffering
+-----------------------------------------
+
+   As a side point, buffering issues can be even more confusing
+depending upon whether or not your program is "interactive", i.e.,
+communicating with a user sitting at a keyboard.(1)
+
+   Interactive programs generally "line buffer" their output; they
+write out every line.  Non-interactive programs wait until they have a
+full buffer, which may be many lines of output.
+
+   Here is an example of the difference.
+
+     $ awk '{ print $1 + $2 }'
+     1 1
+     -| 2
+     2 3
+     -| 5
+     Control-d
+
+Each line of output is printed immediately. Compare that behavior with
+this example.
+
+     $ awk '{ print $1 + $2 }' | cat
+     1 1
+     2 3
+     Control-d
+     -| 2
+     -| 5
+
+Here, no output is printed until after the `Control-D' is typed, since
+it is all buffered, and sent down the pipe to `cat' in one shot.
+
+Controlling Output Buffering with `system'
+------------------------------------------
+
+   The `fflush' function provides explicit control over output
+buffering for individual files and pipes.  However, its use is not
+portable to many other `awk' implementations.  An alternative method to
+flush output buffers is by calling `system' with a null string as its
+argument:
+
+     system("")   # flush output
+
+`gawk' treats this use of the `system' function as a special case, and
+is smart enough not to run a shell (or other command interpreter) with
+the empty command.  Therefore, with `gawk', this idiom is not only
+useful, it is efficient.  While this method should work with other
+`awk' implementations, it will not necessarily avoid starting an
+unnecessary shell.  (Other implementations may only flush the buffer
+associated with the standard output, and not necessarily all buffered
+output.)
+
+   If you think about what a programmer expects, it makes sense that
+`system' should flush any pending output.  The following program:
+
+     BEGIN {
+          print "first print"
+          system("echo system echo")
+          print "second print"
+     }
+
+must print
+
+     first print
+     system echo
+     second print
+
+and not
+
+     system echo
+     first print
+     second print
+
+   If `awk' did not flush its buffers before calling `system', the
+latter (undesirable) output is what you would see.
+
+   ---------- Footnotes ----------
+
+   (1) A program is interactive if the standard output is connected to
+a terminal device.
+
+
+File: gawk.info,  Node: Time Functions,  Prev: I/O Functions,  Up: Built-in
+
+Functions for Dealing with Time Stamps
+======================================
+
+   A common use for `awk' programs is the processing of log files
+containing time stamp information, indicating when a particular log
+record was written.  Many programs log their time stamp in the form
+returned by the `time' system call, which is the number of seconds
+since a particular epoch.  On POSIX systems, it is the number of
+seconds since Midnight, January 1, 1970, UTC.
+
+   In order to make it easier to process such log files, and to produce
+useful reports, `gawk' provides two functions for working with time
+stamps.  Both of these are `gawk' extensions; they are not specified in
+the POSIX standard, nor are they in any other known version of `awk'.
+
+   Optional parameters are enclosed in square brackets ("[" and "]").
+
+`systime()'
+     This function returns the current time as the number of seconds
+     since the system epoch.  On POSIX systems, this is the number of
+     seconds since Midnight, January 1, 1970, UTC.  It may be a
+     different number on other systems.
+
+`strftime([FORMAT [, TIMESTAMP]])'
+     This function returns a string.  It is similar to the function of
+     the same name in ANSI C.  The time specified by TIMESTAMP is used
+     to produce a string, based on the contents of the FORMAT string.
+     The TIMESTAMP is in the same format as the value returned by the
+     `systime' function.  If no TIMESTAMP argument is supplied, `gawk'
+     will use the current time of day as the time stamp.  If no FORMAT
+     argument is supplied, `strftime' uses `"%a %b %d %H:%M:%S %Z %Y"'.
+     This format string produces output (almost) equivalent to that of
+     the `date' utility.  (Versions of `gawk' prior to 3.0 require the
+     FORMAT argument.)
+
+   The `systime' function allows you to compare a time stamp from a log
+file with the current time of day.  In particular, it is easy to
+determine how long ago a particular record was logged.  It also allows
+you to produce log records using the "seconds since the epoch" format.
+
+   The `strftime' function allows you to easily turn a time stamp into
+human-readable information.  It is similar in nature to the `sprintf'
+function (*note Built-in Functions for String Manipulation: String
+Functions.), in that it copies non-format specification characters
+verbatim to the returned string, while substituting date and time
+values for format specifications in the FORMAT string.
+
+   `strftime' is guaranteed by the ANSI C standard to support the
+following date format specifications:
+
+`%a'
+     The locale's abbreviated weekday name.
+
+`%A'
+     The locale's full weekday name.
+
+`%b'
+     The locale's abbreviated month name.
+
+`%B'
+     The locale's full month name.
+
+`%c'
+     The locale's "appropriate" date and time representation.
+
+`%d'
+     The day of the month as a decimal number (01-31).
+
+`%H'
+     The hour (24-hour clock) as a decimal number (00-23).
+
+`%I'
+     The hour (12-hour clock) as a decimal number (01-12).
+
+`%j'
+     The day of the year as a decimal number (001-366).
+
+`%m'
+     The month as a decimal number (01-12).
+
+`%M'
+     The minute as a decimal number (00-59).
+
+`%p'
+     The locale's equivalent of the AM/PM designations associated with
+     a 12-hour clock.
+
+`%S'
+     The second as a decimal number (00-60).(1)
+
+`%U'
+     The week number of the year (the first Sunday as the first day of
+     week one) as a decimal number (00-53).
+
+`%w'
+     The weekday as a decimal number (0-6).  Sunday is day zero.
+
+`%W'
+     The week number of the year (the first Monday as the first day of
+     week one) as a decimal number (00-53).
+
+`%x'
+     The locale's "appropriate" date representation.
+
+`%X'
+     The locale's "appropriate" time representation.
+
+`%y'
+     The year without century as a decimal number (00-99).
+
+`%Y'
+     The year with century as a decimal number (e.g., 1995).
+
+`%Z'
+     The time zone name or abbreviation, or no characters if no time
+     zone is determinable.
+
+`%%'
+     A literal `%'.
+
+   If a conversion specifier is not one of the above, the behavior is
+undefined.(2)
+
+   Informally, a "locale" is the geographic place in which a program is
+meant to run.  For example, a common way to abbreviate the date
+September 4, 1991 in the United States would be "9/4/91".  In many
+countries in Europe, however, it would be abbreviated "4.9.91".  Thus,
+the `%x' specification in a `"US"' locale might produce `9/4/91', while
+in a `"EUROPE"' locale, it might produce `4.9.91'.  The ANSI C standard
+defines a default `"C"' locale, which is an environment that is typical
+of what most C programmers are used to.
+
+   A public-domain C version of `strftime' is supplied with `gawk' for
+systems that are not yet fully ANSI-compliant.  If that version is used
+to compile `gawk' (*note Installing `gawk': Installation.), then the
+following additional format specifications are available:
+
+`%D'
+     Equivalent to specifying `%m/%d/%y'.
+
+`%e'
+     The day of the month, padded with a space if it is only one digit.
+
+`%h'
+     Equivalent to `%b', above.
+
+`%n'
+     A newline character (ASCII LF).
+
+`%r'
+     Equivalent to specifying `%I:%M:%S %p'.
+
+`%R'
+     Equivalent to specifying `%H:%M'.
+
+`%T'
+     Equivalent to specifying `%H:%M:%S'.
+
+`%t'
+     A tab character.
+
+`%k'
+     The hour (24-hour clock) as a decimal number (0-23).  Single digit
+     numbers are padded with a space.
+
+`%l'
+     The hour (12-hour clock) as a decimal number (1-12).  Single digit
+     numbers are padded with a space.
+
+`%C'
+     The century, as a number between 00 and 99.
+
+`%u'
+     The weekday as a decimal number [1 (Monday)-7].
+
+`%V'
+     The week number of the year (the first Monday as the first day of
+     week one) as a decimal number (01-53).  The method for determining
+     the week number is as specified by ISO 8601 (to wit: if the week
+     containing January 1 has four or more days in the new year, then
+     it is week one, otherwise it is week 53 of the previous year and
+     the next week is week one).
+
+`%G'
+     The year with century of the ISO week number, as a decimal number.
+
+     For example, January 1, 1993, is in week 53 of 1992. Thus, the year
+     of its ISO week number is 1992, even though its year is 1993.
+     Similarly, December 31, 1973, is in week 1 of 1974. Thus, the year
+     of its ISO week number is 1974, even though its year is 1973.
+
+`%g'
+     The year without century of the ISO week number, as a decimal
+     number (00-99).
+
+`%Ec %EC %Ex %Ey %EY %Od %Oe %OH %OI'
+`%Om %OM %OS %Ou %OU %OV %Ow %OW %Oy'
+     These are "alternate representations" for the specifications that
+     use only the second letter (`%c', `%C', and so on).  They are
+     recognized, but their normal representations are used.(3) (These
+     facilitate compliance with the POSIX `date' utility.)
+
+`%v'
+     The date in VMS format (e.g., 20-JUN-1991).
+
+`%z'
+     The timezone offset in a +HHMM format (e.g., the format necessary
+     to produce RFC-822/RFC-1036 date headers).
+
+   This example is an `awk' implementation of the POSIX `date' utility.
+Normally, the `date' utility prints the current date and time of day
+in a well known format.  However, if you provide an argument to it that
+begins with a `+', `date' will copy non-format specifier characters to
+the standard output, and will interpret the current time according to
+the format specifiers in the string.  For example:
+
+     $ date '+Today is %A, %B %d, %Y.'
+     -| Today is Thursday, July 11, 1991.
+
+   Here is the `gawk' version of the `date' utility.  It has a shell
+"wrapper", to handle the `-u' option, which requires that `date' run as
+if the time zone was set to UTC.
+
+     #! /bin/sh
+     #
+     # date --- approximate the P1003.2 'date' command
+     
+     case $1 in
+     -u)  TZ=GMT0     # use UTC
+          export TZ
+          shift ;;
+     esac
+     
+     gawk 'BEGIN  {
+         format = "%a %b %d %H:%M:%S %Z %Y"
+         exitval = 0
+     
+         if (ARGC > 2)
+             exitval = 1
+         else if (ARGC == 2) {
+             format = ARGV[1]
+             if (format ~ /^\+/)
+                 format = substr(format, 2)   # remove leading +
+         }
+         print strftime(format)
+         exit exitval
+     }' "$@"
+
+   ---------- Footnotes ----------
+
+   (1) Occasionally there are minutes in a year with a leap second,
+which is why the seconds can go up to 60.
+
+   (2) This is because ANSI C leaves the behavior of the C version of
+`strftime' undefined, and `gawk' will use the system's version of
+`strftime' if it's there.  Typically, the conversion specifier will
+either not appear in the returned string, or it will appear literally.
+
+   (3) If you don't understand any of this, don't worry about it; these
+facilities are meant to make it easier to "internationalize" programs.
+
+
+File: gawk.info,  Node: User-defined,  Next: Invoking Gawk,  Prev: Built-in,  Up: Top
+
+User-defined Functions
+**********************
+
+   Complicated `awk' programs can often be simplified by defining your
+own functions.  User-defined functions can be called just like built-in
+ones (*note Function Calls::), but it is up to you to define them--to
+tell `awk' what they should do.
+
+* Menu:
+
+* Definition Syntax::           How to write definitions and what they mean.
+* Function Example::            An example function definition and what it
+                                does.
+* Function Caveats::            Things to watch out for.
+* Return Statement::            Specifying the value a function returns.
+
+
+File: gawk.info,  Node: Definition Syntax,  Next: Function Example,  Prev: User-defined,  Up: User-defined
+
+Function Definition Syntax
+==========================
+
+   Definitions of functions can appear anywhere between the rules of an
+`awk' program.  Thus, the general form of an `awk' program is extended
+to include sequences of rules _and_ user-defined function definitions.
+There is no need in `awk' to put the definition of a function before
+all uses of the function.  This is because `awk' reads the entire
+program before starting to execute any of it.
+
+   The definition of a function named NAME looks like this:
+
+     function NAME(PARAMETER-LIST)
+     {
+          BODY-OF-FUNCTION
+     }
+
+NAME is the name of the function to be defined.  A valid function name
+is like a valid variable name: a sequence of letters, digits and
+underscores, not starting with a digit.  Within a single `awk' program,
+any particular name can only be used as a variable, array or function.
+
+   PARAMETER-LIST is a list of the function's arguments and local
+variable names, separated by commas.  When the function is called, the
+argument names are used to hold the argument values given in the call.
+The local variables are initialized to the empty string.  A function
+cannot have two parameters with the same name.
+
+   The BODY-OF-FUNCTION consists of `awk' statements.  It is the most
+important part of the definition, because it says what the function
+should actually _do_.  The argument names exist to give the body a way
+to talk about the arguments; local variables, to give the body places
+to keep temporary values.
+
+   Argument names are not distinguished syntactically from local
+variable names; instead, the number of arguments supplied when the
+function is called determines how many argument variables there are.
+Thus, if three argument values are given, the first three names in
+PARAMETER-LIST are arguments, and the rest are local variables.
+
+   It follows that if the number of arguments is not the same in all
+calls to the function, some of the names in PARAMETER-LIST may be
+arguments on some occasions and local variables on others.  Another way
+to think of this is that omitted arguments default to the null string.
+
+   Usually when you write a function you know how many names you intend
+to use for arguments and how many you intend to use as local variables.
+It is conventional to place some extra space between the arguments and
+the local variables, to document how your function is supposed to be
+used.
+
+   During execution of the function body, the arguments and local
+variable values hide or "shadow" any variables of the same names used
+in the rest of the program.  The shadowed variables are not accessible
+in the function definition, because there is no way to name them while
+their names have been taken away for the local variables.  All other
+variables used in the `awk' program can be referenced or set normally
+in the function's body.
+
+   The arguments and local variables last only as long as the function
+body is executing.  Once the body finishes, you can once again access
+the variables that were shadowed while the function was running.
+
+   The function body can contain expressions which call functions.  They
+can even call this function, either directly or by way of another
+function.  When this happens, we say the function is "recursive".
+
+   In many `awk' implementations, including `gawk', the keyword
+`function' may be abbreviated `func'.  However, POSIX only specifies
+the use of the keyword `function'.  This actually has some practical
+implications.  If `gawk' is in POSIX-compatibility mode (*note Command
+Line Options: Options.), then the following statement will _not_ define
+a function:
+
+     func foo() { a = sqrt($1) ; print a }
+
+Instead it defines a rule that, for each record, concatenates the value
+of the variable `func' with the return value of the function `foo'.  If
+the resulting string is non-null, the action is executed.  This is
+probably not what was desired.  (`awk' accepts this input as
+syntactically valid, since functions may be used before they are defined
+in `awk' programs.)
+
+   To ensure that your `awk' programs are portable, always use the
+keyword `function' when defining a function.
+
+
+File: gawk.info,  Node: Function Example,  Next: Function Caveats,  Prev: Definition Syntax,  Up: User-defined
+
+Function Definition Examples
+============================
+
+   Here is an example of a user-defined function, called `myprint', that
+takes a number and prints it in a specific format.
+
+     function myprint(num)
+     {
+          printf "%6.3g\n", num
+     }
+
+To illustrate, here is an `awk' rule which uses our `myprint' function:
+
+     $3 > 0     { myprint($3) }
+
+This program prints, in our special format, all the third fields that
+contain a positive number in our input.  Therefore, when given:
+
+      1.2   3.4    5.6   7.8
+      9.10 11.12 -13.14 15.16
+     17.18 19.20  21.22 23.24
+
+this program, using our function to format the results, prints:
+
+        5.6
+       21.2
+
+   This function deletes all the elements in an array.
+
+     function delarray(a,    i)
+     {
+         for (i in a)
+            delete a[i]
+     }
+
+   When working with arrays, it is often necessary to delete all the
+elements in an array and start over with a new list of elements (*note
+The `delete' Statement: Delete.).  Instead of having to repeat this
+loop everywhere in your program that you need to clear out an array,
+your program can just call `delarray'.
+
+   Here is an example of a recursive function.  It takes a string as an
+input parameter, and returns the string in backwards order.
+
+     function rev(str, start)
+     {
+         if (start == 0)
+             return ""
+     
+         return (substr(str, start, 1) rev(str, start - 1))
+     }
+
+   If this function is in a file named `rev.awk', we can test it this
+way:
+
+     $ echo "Don't Panic!" |
+     > gawk --source '{ print rev($0, length($0)) }' -f rev.awk
+     -| !cinaP t'noD
+
+   Here is an example that uses the built-in function `strftime'.
+(*Note Functions for Dealing with Time Stamps: Time Functions, for more
+information on `strftime'.)  The C `ctime' function takes a timestamp
+and returns it in a string, formatted in a well known fashion.  Here is
+an `awk' version:
+
+     # ctime.awk
+     #
+     # awk version of C ctime(3) function
+     
+     function ctime(ts,    format)
+     {
+         format = "%a %b %d %H:%M:%S %Z %Y"
+         if (ts == 0)
+             ts = systime()       # use current time as default
+         return strftime(format, ts)
+     }
+
+
+File: gawk.info,  Node: Function Caveats,  Next: Return Statement,  Prev: Function Example,  Up: User-defined
+
+Calling User-defined Functions
+==============================
+
+   "Calling a function" means causing the function to run and do its
+job.  A function call is an expression, and its value is the value
+returned by the function.
+
+   A function call consists of the function name followed by the
+arguments in parentheses.  What you write in the call for the arguments
+are `awk' expressions; each time the call is executed, these
+expressions are evaluated, and the values are the actual arguments.  For
+example, here is a call to `foo' with three arguments (the first being
+a string concatenation):
+
+     foo(x y, "lose", 4 * z)
+
+   *Caution:* whitespace characters (spaces and tabs) are not allowed
+between the function name and the open-parenthesis of the argument list.
+If you write whitespace by mistake, `awk' might think that you mean to
+concatenate a variable with an expression in parentheses.  However, it
+notices that you used a function name and not a variable name, and
+reports an error.
+
+   When a function is called, it is given a _copy_ of the values of its
+arguments.  This is known as "call by value".  The caller may use a
+variable as the expression for the argument, but the called function
+does not know this: it only knows what value the argument had.  For
+example, if you write this code:
+
+     foo = "bar"
+     z = myfunc(foo)
+
+then you should not think of the argument to `myfunc' as being "the
+variable `foo'."  Instead, think of the argument as the string value,
+`"bar"'.
+
+   If the function `myfunc' alters the values of its local variables,
+this has no effect on any other variables.  Thus, if `myfunc' does this:
+
+     function myfunc(str)
+     {
+       print str
+       str = "zzz"
+       print str
+     }
+
+to change its first argument variable `str', this _does not_ change the
+value of `foo' in the caller.  The role of `foo' in calling `myfunc'
+ended when its value, `"bar"', was computed.  If `str' also exists
+outside of `myfunc', the function body cannot alter this outer value,
+because it is shadowed during the execution of `myfunc' and cannot be
+seen or changed from there.
+
+   However, when arrays are the parameters to functions, they are _not_
+copied.  Instead, the array itself is made available for direct
+manipulation by the function.  This is usually called "call by
+reference".  Changes made to an array parameter inside the body of a
+function _are_ visible outside that function.  This can be *very*
+dangerous if you do not watch what you are doing.  For example:
+
+     function changeit(array, ind, nvalue)
+     {
+          array[ind] = nvalue
+     }
+     
+     BEGIN {
+         a[1] = 1; a[2] = 2; a[3] = 3
+         changeit(a, 2, "two")
+         printf "a[1] = %s, a[2] = %s, a[3] = %s\n",
+                 a[1], a[2], a[3]
+     }
+
+This program prints `a[1] = 1, a[2] = two, a[3] = 3', because
+`changeit' stores `"two"' in the second element of `a'.
+
+   Some `awk' implementations allow you to call a function that has not
+been defined, and only report a problem at run-time when the program
+actually tries to call the function. For example:
+
+     BEGIN {
+         if (0)
+             foo()
+         else
+             bar()
+     }
+     function bar() { ... }
+     # note that `foo' is not defined
+
+Since the `if' statement will never be true, it is not really a problem
+that `foo' has not been defined.  Usually though, it is a problem if a
+program calls an undefined function.
+
+   If `--lint' has been specified (*note Command Line Options:
+Options.), `gawk' will report about calls to undefined functions.
+
+   Some `awk' implementations generate a run-time error if you use the
+`next' statement (*note The `next' Statement: Next Statement.)  inside
+a user-defined function.  `gawk' does not have this problem.
+
+
+File: gawk.info,  Node: Return Statement,  Prev: Function Caveats,  Up: User-defined
+
+The `return' Statement
+======================
+
+   The body of a user-defined function can contain a `return' statement.
+This statement returns control to the rest of the `awk' program.  It
+can also be used to return a value for use in the rest of the `awk'
+program.  It looks like this:
+
+     return [EXPRESSION]
+
+   The EXPRESSION part is optional.  If it is omitted, then the returned
+value is undefined and, therefore, unpredictable.
+
+   A `return' statement with no value expression is assumed at the end
+of every function definition.  So if control reaches the end of the
+function body, then the function returns an unpredictable value.  `awk'
+will _not_ warn you if you use the return value of such a function.
+
+   Sometimes, you want to write a function for what it does, not for
+what it returns.  Such a function corresponds to a `void' function in C
+or to a `procedure' in Pascal.  Thus, it may be appropriate to not
+return any value; you should simply bear in mind that if you use the
+return value of such a function, you do so at your own risk.
+
+   Here is an example of a user-defined function that returns a value
+for the largest number among the elements of an array:
+
+     function maxelt(vec,   i, ret)
+     {
+          for (i in vec) {
+               if (ret == "" || vec[i] > ret)
+                    ret = vec[i]
+          }
+          return ret
+     }
+
+You call `maxelt' with one argument, which is an array name.  The local
+variables `i' and `ret' are not intended to be arguments; while there
+is nothing to stop you from passing two or three arguments to `maxelt',
+the results would be strange.  The extra space before `i' in the
+function parameter list indicates that `i' and `ret' are not supposed
+to be arguments.  This is a convention that you should follow when you
+define functions.
+
+   Here is a program that uses our `maxelt' function.  It loads an
+array, calls `maxelt', and then reports the maximum number in that
+array:
+
+     awk '
+     function maxelt(vec,   i, ret)
+     {
+          for (i in vec) {
+               if (ret == "" || vec[i] > ret)
+                    ret = vec[i]
+          }
+          return ret
+     }
+     
+     # Load all fields of each record into nums.
+     {
+          for(i = 1; i <= NF; i++)
+               nums[NR, i] = $i
+     }
+     
+     END {
+          print maxelt(nums)
+     }'
+
+   Given the following input:
+
+      1 5 23 8 16
+     44 3 5 2 8 26
+     256 291 1396 2962 100
+     -6 467 998 1101
+     99385 11 0 225
+
+our program tells us (predictably) that `99385' is the largest number
+in our array.
+
+
+File: gawk.info,  Node: Invoking Gawk,  Next: Library Functions,  Prev: User-defined,  Up: Top
+
+Running `awk'
+*************
+
+   There are two ways to run `awk': with an explicit program, or with
+one or more program files.  Here are templates for both of them; items
+enclosed in `[...]' in these templates are optional.
+
+   Besides traditional one-letter POSIX-style options, `gawk' also
+supports GNU long options.
+
+     awk [OPTIONS] -f progfile [`--'] FILE ...
+     awk [OPTIONS] [`--'] 'PROGRAM' FILE ...
+
+   It is possible to invoke `awk' with an empty program:
+
+     $ awk '' datafile1 datafile2
+
+Doing so makes little sense though; `awk' will simply exit silently
+when given an empty program (d.c.).  If `--lint' has been specified on
+the command line, `gawk' will issue a warning that the program is empty.
+
+* Menu:
+
+* Options::                     Command line options and their meanings.
+* Other Arguments::             Input file names and variable assignments.
+* AWKPATH Variable::            Searching directories for `awk' programs.
+* Obsolete::                    Obsolete Options and/or features.
+* Undocumented::                Undocumented Options and Features.
+* Known Bugs::                  Known Bugs in `gawk'.
+
+
+File: gawk.info,  Node: Options,  Next: Other Arguments,  Prev: Invoking Gawk,  Up: Invoking Gawk
+
+Command Line Options
+====================
+
+   Options begin with a dash, and consist of a single character.  GNU
+style long options consist of two dashes and a keyword.  The keyword
+can be abbreviated, as long the abbreviation allows the option to be
+uniquely identified.  If the option takes an argument, then the keyword
+is either immediately followed by an equals sign (`=') and the
+argument's value, or the keyword and the argument's value are separated
+by whitespace.  For brevity, the discussion below only refers to the
+traditional short options; however the long and short options are
+interchangeable in all contexts.
+
+   Each long option for `gawk' has a corresponding POSIX-style option.
+The options and their meanings are as follows:
+
+`-F FS'
+`--field-separator FS'
+     Sets the `FS' variable to FS (*note Specifying How Fields are
+     Separated: Field Separators.).
+
+`-f SOURCE-FILE'
+`--file SOURCE-FILE'
+     Indicates that the `awk' program is to be found in SOURCE-FILE
+     instead of in the first non-option argument.
+
+`-v VAR=VAL'
+`--assign VAR=VAL'
+     Sets the variable VAR to the value VAL *before* execution of the
+     program begins.  Such variable values are available inside the
+     `BEGIN' rule (*note Other Command Line Arguments: Other
+     Arguments.).
+
+     The `-v' option can only set one variable, but you can use it more
+     than once, setting another variable each time, like this: `awk
+     -v foo=1 -v bar=2 ...'.
+
+`-mf NNN'
+`-mr NNN'
+     Set various memory limits to the value NNN.  The `f' flag sets the
+     maximum number of fields, and the `r' flag sets the maximum record
+     size.  These two flags and the `-m' option are from the Bell Labs
+     research version of Unix `awk'.  They are provided for
+     compatibility, but otherwise ignored by `gawk', since `gawk' has
+     no predefined limits.
+
+`-W GAWK-OPT'
+     Following the POSIX standard, options that are implementation
+     specific are supplied as arguments to the `-W' option.  These
+     options also have corresponding GNU style long options.  See below.
+
+`--'
+     Signals the end of the command line options.  The following
+     arguments are not treated as options even if they begin with `-'.
+     This interpretation of `--' follows the POSIX argument parsing
+     conventions.
+
+     This is useful if you have file names that start with `-', or in
+     shell scripts, if you have file names that will be specified by
+     the user which could start with `-'.
+
+   The following `gawk'-specific options are available:
+
+`-W traditional'
+`-W compat'
+`--traditional'
+`--compat'
+     Specifies "compatibility mode", in which the GNU extensions to the
+     `awk' language are disabled, so that `gawk' behaves just like the
+     Bell Labs research version of Unix `awk'.  `--traditional' is the
+     preferred form of this option.  *Note Extensions in `gawk' Not in
+     POSIX `awk': POSIX/GNU, which summarizes the extensions.  Also see
+     *Note Downward Compatibility and Debugging: Compatibility Mode.
+
+`-W copyleft'
+`-W copyright'
+`--copyleft'
+`--copyright'
+     Print the short version of the General Public License, and then
+     exit.  This option may disappear in a future version of `gawk'.
+
+`-W help'
+`-W usage'
+`--help'
+`--usage'
+     Print a "usage" message summarizing the short and long style
+     options that `gawk' accepts, and then exit.
+
+`-W lint'
+`--lint'
+     Warn about constructs that are dubious or non-portable to other
+     `awk' implementations.  Some warnings are issued when `gawk' first
+     reads your program.  Others are issued at run-time, as your
+     program executes.
+
+`-W lint-old'
+`--lint-old'
+     Warn about constructs that are not available in the original
+     Version 7 Unix version of `awk' (*note Major Changes between V7
+     and SVR3.1: V7/SVR3.1.).
+
+`-W posix'
+`--posix'
+     Operate in strict POSIX mode.  This disables all `gawk' extensions
+     (just like `--traditional'), and adds the following additional
+     restrictions:
+
+        * `\x' escape sequences are not recognized (*note Escape
+          Sequences::).
+
+        * Newlines do not act as whitespace to separate fields when
+          `FS' is equal to a single space.
+
+        * The synonym `func' for the keyword `function' is not
+          recognized (*note Function Definition Syntax: Definition
+          Syntax.).
+
+        * The operators `**' and `**=' cannot be used in place of `^'
+          and `^=' (*note Arithmetic Operators: Arithmetic Ops., and
+          also *note Assignment Expressions: Assignment Ops.).
+
+        * Specifying `-Ft' on the command line does not set the value
+          of `FS' to be a single tab character (*note Specifying How
+          Fields are Separated: Field Separators.).
+
+        * The `fflush' built-in function is not supported (*note
+          Built-in Functions for Input/Output: I/O Functions.).
+
+     If you supply both `--traditional' and `--posix' on the command
+     line, `--posix' will take precedence. `gawk' will also issue a
+     warning if both options are supplied.
+
+`-W re-interval'
+`--re-interval'
+     Allow interval expressions (*note Regular Expression Operators:
+     Regexp Operators.), in regexps.  Because interval expressions were
+     traditionally not available in `awk', `gawk' does not provide them
+     by default. This prevents old `awk' programs from breaking.
+
+`-W source PROGRAM-TEXT'
+`--source PROGRAM-TEXT'
+     Program source code is taken from the PROGRAM-TEXT.  This option
+     allows you to mix source code in files with source code that you
+     enter on the command line. This is particularly useful when you
+     have library functions that you wish to use from your command line
+     programs (*note The `AWKPATH' Environment Variable: AWKPATH
+     Variable.).
+
+`-W version'
+`--version'
+     Prints version information for this particular copy of `gawk'.
+     This allows you to determine if your copy of `gawk' is up to date
+     with respect to whatever the Free Software Foundation is currently
+     distributing.  It is also useful for bug reports (*note Reporting
+     Problems and Bugs: Bugs.).
+
+   Any other options are flagged as invalid with a warning message, but
+are otherwise ignored.
+
+   In compatibility mode, as a special case, if the value of FS supplied
+to the `-F' option is `t', then `FS' is set to the tab character
+(`"\t"').  This is only true for `--traditional', and not for `--posix'
+(*note Specifying How Fields are Separated: Field Separators.).
+
+   The `-f' option may be used more than once on the command line.  If
+it is, `awk' reads its program source from all of the named files, as
+if they had been concatenated together into one big file.  This is
+useful for creating libraries of `awk' functions.  Useful functions can
+be written once, and then retrieved from a standard place, instead of
+having to be included into each individual program.
+
+   You can type in a program at the terminal and still use library
+functions, by specifying `-f /dev/tty'.  `awk' will read a file from
+the terminal to use as part of the `awk' program.  After typing your
+program, type `Control-d' (the end-of-file character) to terminate it.
+(You may also use `-f -' to read program source from the standard
+input, but then you will not be able to also use the standard input as a
+source of data.)
+
+   Because it is clumsy using the standard `awk' mechanisms to mix
+source file and command line `awk' programs, `gawk' provides the
+`--source' option.  This does not require you to pre-empt the standard
+input for your source code, and allows you to easily mix command line
+and library source code (*note The `AWKPATH' Environment Variable:
+AWKPATH Variable.).
+
+   If no `-f' or `--source' option is specified, then `gawk' will use
+the first non-option command line argument as the text of the program
+source code.
+
+   If the environment variable `POSIXLY_CORRECT' exists, then `gawk'
+will behave in strict POSIX mode, exactly as if you had supplied the
+`--posix' command line option.  Many GNU programs look for this
+environment variable to turn on strict POSIX mode. If you supply
+`--lint' on the command line, and `gawk' turns on POSIX mode because of
+`POSIXLY_CORRECT', then it will print a warning message indicating that
+POSIX mode is in effect.
+
+   You would typically set this variable in your shell's startup file.
+For a Bourne compatible shell (such as Bash), you would add these lines
+to the `.profile' file in your home directory.
+
+     POSIXLY_CORRECT=true
+     export POSIXLY_CORRECT
+
+   For a `csh' compatible shell,(1) you would add this line to the
+`.login' file in your home directory.
+
+     setenv POSIXLY_CORRECT true
+
+   ---------- Footnotes ----------
+
+   (1) Not recommended.
+
+
+File: gawk.info,  Node: Other Arguments,  Next: AWKPATH Variable,  Prev: Options,  Up: Invoking Gawk
+
+Other Command Line Arguments
+============================
+
+   Any additional arguments on the command line are normally treated as
+input files to be processed in the order specified.   However, an
+argument that has the form `VAR=VALUE', assigns the value VALUE to the
+variable VAR--it does not specify a file at all.
+
+   All these arguments are made available to your `awk' program in the
+`ARGV' array (*note Built-in Variables::).  Command line options and
+the program text (if present) are omitted from `ARGV'.  All other
+arguments, including variable assignments, are included.   As each
+element of `ARGV' is processed, `gawk' sets the variable `ARGIND' to
+the index in `ARGV' of the current element.
+
+   The distinction between file name arguments and variable-assignment
+arguments is made when `awk' is about to open the next input file.  At
+that point in execution, it checks the "file name" to see whether it is
+really a variable assignment; if so, `awk' sets the variable instead of
+reading a file.
+
+   Therefore, the variables actually receive the given values after all
+previously specified files have been read.  In particular, the values of
+variables assigned in this fashion are _not_ available inside a `BEGIN'
+rule (*note The `BEGIN' and `END' Special Patterns: BEGIN/END.), since
+such rules are run before `awk' begins scanning the argument list.
+
+   The variable values given on the command line are processed for
+escape sequences (d.c.) (*note Escape Sequences::).
+
+   In some earlier implementations of `awk', when a variable assignment
+occurred before any file names, the assignment would happen _before_
+the `BEGIN' rule was executed.  `awk''s behavior was thus inconsistent;
+some command line assignments were available inside the `BEGIN' rule,
+while others were not.  However, some applications came to depend upon
+this "feature."  When `awk' was changed to be more consistent, the `-v'
+option was added to accommodate applications that depended upon the old
+behavior.
+
+   The variable assignment feature is most useful for assigning to
+variables such as `RS', `OFS', and `ORS', which control input and
+output formats, before scanning the data files.  It is also useful for
+controlling state if multiple passes are needed over a data file.  For
+example:
+
+     awk 'pass == 1  { PASS 1 STUFF }
+          pass == 2  { PASS 2 STUFF }' pass=1 mydata pass=2 mydata
+
+   Given the variable assignment feature, the `-F' option for setting
+the value of `FS' is not strictly necessary.  It remains for historical
+compatibility.
+
+
+File: gawk.info,  Node: AWKPATH Variable,  Next: Obsolete,  Prev: Other Arguments,  Up: Invoking Gawk
+
+The `AWKPATH' Environment Variable
+==================================
+
+   The previous section described how `awk' program files can be named
+on the command line with the `-f' option.  In most `awk'
+implementations, you must supply a precise path name for each program
+file, unless the file is in the current directory.
+
+   But in `gawk', if the file name supplied to the `-f' option does not
+contain a `/', then `gawk' searches a list of directories (called the
+"search path"), one by one, looking for a file with the specified name.
+
+   The search path is a string consisting of directory names separated
+by colons.  `gawk' gets its search path from the `AWKPATH' environment
+variable.  If that variable does not exist, `gawk' uses a default path,
+which is `.:/usr/local/share/awk'.(1) (Programs written for use by
+system administrators should use an `AWKPATH' variable that does not
+include the current directory, `.'.)
+
+   The search path feature is particularly useful for building up
+libraries of useful `awk' functions.  The library files can be placed
+in a standard directory that is in the default path, and then specified
+on the command line with a short file name.  Otherwise, the full file
+name would have to be typed for each file.
+
+   By using both the `--source' and `-f' options, your command line
+`awk' programs can use facilities in `awk' library files.  *Note A
+Library of `awk' Functions: Library Functions.
+
+   Path searching is not done if `gawk' is in compatibility mode.  This
+is true for both `--traditional' and `--posix'.  *Note Command Line
+Options: Options.
+
+   *Note:* if you want files in the current directory to be found, you
+must include the current directory in the path, either by including `.'
+explicitly in the path, or by writing a null entry in the path.  (A
+null entry is indicated by starting or ending the path with a colon, or
+by placing two colons next to each other (`::').)  If the current
+directory is not included in the path, then files cannot be found in
+the current directory.  This path search mechanism is identical to the
+shell's.
+
+   Starting with version 3.0, if `AWKPATH' is not defined in the
+environment, `gawk' will place its default search path into
+`ENVIRON["AWKPATH"]'. This makes it easy to determine the actual search
+path `gawk' will use.
+
+   ---------- Footnotes ----------
+
+   (1) Your version of `gawk' may use a directory that is different
+than `/usr/local/share/awk'; it will depend upon how `gawk' was built
+and installed. The actual directory will be the value of `$(datadir)'
+generated when `gawk' was configured.  You probably don't need to worry
+about this though.
+
+
+File: gawk.info,  Node: Obsolete,  Next: Undocumented,  Prev: AWKPATH Variable,  Up: Invoking Gawk
+
+Obsolete Options and/or Features
+================================
+
+   This section describes features and/or command line options from
+previous releases of `gawk' that are either not available in the
+current version, or that are still supported but deprecated (meaning
+that they will _not_ be in the next release).
+
+   For version 3.0.1 of `gawk', there are no command line options or
+other deprecated features from the previous version of `gawk'.  This
+node is thus essentially a place holder, in case some option becomes
+obsolete in a future version of `gawk'.
+
+
+File: gawk.info,  Node: Undocumented,  Next: Known Bugs,  Prev: Obsolete,  Up: Invoking Gawk
+
+Undocumented Options and Features
+=================================
+
+   This section intentionally left blank.
+
+
+File: gawk.info,  Node: Known Bugs,  Prev: Undocumented,  Up: Invoking Gawk
+
+Known Bugs in `gawk'
+====================
+
+   * The `-F' option for changing the value of `FS' (*note Command Line
+     Options: Options.)  is not necessary given the command line
+     variable assignment feature; it remains only for backwards
+     compatibility.
+
+   * If your system actually has support for `/dev/fd' and the
+     associated `/dev/stdin', `/dev/stdout', and `/dev/stderr' files,
+     you may get different output from `gawk' than you would get on a
+     system without those files.  When `gawk' interprets these files
+     internally, it synchronizes output to the standard output with
+     output to `/dev/stdout', while on a system with those files, the
+     output is actually to different open files (*note Special File
+     Names in `gawk': Special Files.).
+
+   * Syntactically invalid single character programs tend to overflow
+     the parse stack, generating a rather unhelpful message.  Such
+     programs are surprisingly difficult to diagnose in the completely
+     general case, and the effort to do so really is not worth it.
+
+
+File: gawk.info,  Node: Library Functions,  Next: Sample Programs,  Prev: Invoking Gawk,  Up: Top
+
+A Library of `awk' Functions
+****************************
+
+   This chapter presents a library of useful `awk' functions.  The
+sample programs presented later (*note Practical `awk' Programs: Sample
+Programs.)  use these functions.  The functions are presented here in a
+progression from simple to complex.
+
+   *Note Extracting Programs from Texinfo Source Files: Extract Program,
+presents a program that you can use to extract the source code for
+these example library functions and programs from the Texinfo source
+for this Info file.  (This has already been done as part of the `gawk'
+distribution.)
+
+   If you have written one or more useful, general purpose `awk'
+functions, and would like to contribute them for a subsequent edition
+of this Info file, please contact the author.  *Note Reporting Problems
+and Bugs: Bugs, for information on doing this.  Don't just send code,
+as you will be required to either place your code in the public domain,
+publish it under the GPL (*note GNU GENERAL PUBLIC LICENSE: Copying.),
+or assign the copyright in it to the Free Software Foundation.
+
+* Menu:
+
+* Portability Notes::           What to do if you don't have `gawk'.
+* Nextfile Function::           Two implementations of a `nextfile'
+                                function.
+* Assert Function::             A function for assertions in `awk'
+                                programs.
+* Round Function::              A function for rounding if `sprintf' does
+                                not do it correctly.
+* Ordinal Functions::           Functions for using characters as numbers and
+                                vice versa.
+* Join Function::               A function to join an array into a string.
+* Mktime Function::             A function to turn a date into a timestamp.
+* Gettimeofday Function::       A function to get formatted times.
+* Filetrans Function::          A function for handling data file transitions.
+* Getopt Function::             A function for processing command line
+                                arguments.
+* Passwd Functions::            Functions for getting user information.
+* Group Functions::             Functions for getting group information.
+* Library Names::               How to best name private global variables in
+                                library functions.
+
+
+File: gawk.info,  Node: Portability Notes,  Next: Nextfile Function,  Prev: Library Functions,  Up: Library Functions
+
+Simulating `gawk'-specific Features
+===================================
+
+   The programs in this chapter and in *Note Practical `awk' Programs:
+Sample Programs, freely use features that are specific to `gawk'.  This
+section briefly discusses how you can rewrite these programs for
+different implementations of `awk'.
+
+   Diagnostic error messages are sent to `/dev/stderr'.  Use `| "cat
+1>&2"' instead of `> "/dev/stderr"', if your system does not have a
+`/dev/stderr', or if you cannot use `gawk'.
+
+   A number of programs use `nextfile' (*note The `nextfile' Statement:
+Nextfile Statement.), to skip any remaining input in the input file.
+*Note Implementing `nextfile' as a Function: Nextfile Function, shows
+you how to write a function that will do the same thing.
+
+   Finally, some of the programs choose to ignore upper-case and
+lower-case distinctions in their input. They do this by assigning one
+to `IGNORECASE'.  You can achieve the same effect by adding the
+following rule to the beginning of the program:
+
+     # ignore case
+     { $0 = tolower($0) }
+
+Also, verify that all regexp and string constants used in comparisons
+only use lower-case letters.
+
+
+File: gawk.info,  Node: Nextfile Function,  Next: Assert Function,  Prev: Portability Notes,  Up: Library Functions
+
+Implementing `nextfile' as a Function
+=====================================
+
+   The `nextfile' statement presented in *Note The `nextfile'
+Statement: Nextfile Statement, is a `gawk'-specific extension.  It is
+not available in other implementations of `awk'.  This section shows
+two versions of a `nextfile' function that you can use to simulate
+`gawk''s `nextfile' statement if you cannot use `gawk'.
+
+   Here is a first attempt at writing a `nextfile' function.
+
+     # nextfile --- skip remaining records in current file
+     
+     # this should be read in before the "main" awk program
+     
+     function nextfile()    { _abandon_ = FILENAME; next }
+     
+     _abandon_ == FILENAME  { next }
+
+   This file should be included before the main program, because it
+supplies a rule that must be executed first.  This rule compares the
+current data file's name (which is always in the `FILENAME' variable)
+to a private variable named `_abandon_'.  If the file name matches,
+then the action part of the rule executes a `next' statement, to go on
+to the next record.  (The use of `_' in the variable name is a
+convention.  It is discussed more fully in *Note Naming Library
+Function Global Variables: Library Names.)
+
+   The use of the `next' statement effectively creates a loop that reads
+all the records from the current data file.  Eventually, the end of the
+file is reached, and a new data file is opened, changing the value of
+`FILENAME'.  Once this happens, the comparison of `_abandon_' to
+`FILENAME' fails, and execution continues with the first rule of the
+"real" program.
+
+   The `nextfile' function itself simply sets the value of `_abandon_'
+and then executes a `next' statement to start the loop going.(1)
+
+   This initial version has a subtle problem.  What happens if the same
+data file is listed _twice_ on the command line, one right after the
+other, or even with just a variable assignment between the two
+occurrences of the file name?
+
+   In such a case, this code will skip right through the file, a second
+time, even though it should stop when it gets to the end of the first
+occurrence.  Here is a second version of `nextfile' that remedies this
+problem.
+
+     # nextfile --- skip remaining records in current file
+     # correctly handle successive occurrences of the same file
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May, 1993
+     
+     # this should be read in before the "main" awk program
+     
+     function nextfile()   { _abandon_ = FILENAME; next }
+     
+     _abandon_ == FILENAME {
+           if (FNR == 1)
+               _abandon_ = ""
+           else
+               next
+     }
+
+   The `nextfile' function has not changed.  It sets `_abandon_' equal
+to the current file name and then executes a `next' satement.  The
+`next' statement reads the next record and increments `FNR', so `FNR'
+is guaranteed to have a value of at least two.  However, if `nextfile'
+is called for the last record in the file, then `awk' will close the
+current data file and move on to the next one.  Upon doing so,
+`FILENAME' will be set to the name of the new file, and `FNR' will be
+reset to one.  If this next file is the same as the previous one,
+`_abandon_' will still be equal to `FILENAME'.  However, `FNR' will be
+equal to one, telling us that this is a new occurrence of the file, and
+not the one we were reading when the `nextfile' function was executed.
+In that case, `_abandon_' is reset to the empty string, so that further
+executions of this rule will fail (until the next time that `nextfile'
+is called).
+
+   If `FNR' is not one, then we are still in the original data file,
+and the program executes a `next' statement to skip through it.
+
+   An important question to ask at this point is: "Given that the
+functionality of `nextfile' can be provided with a library file, why is
+it built into `gawk'?"  This is an important question.  Adding features
+for little reason leads to larger, slower programs that are harder to
+maintain.
+
+   The answer is that building `nextfile' into `gawk' provides
+significant gains in efficiency.  If the `nextfile' function is executed
+at the beginning of a large data file, `awk' still has to scan the
+entire file, splitting it up into records, just to skip over it.  The
+built-in `nextfile' can simply close the file immediately and proceed
+to the next one, saving a lot of time.  This is particularly important
+in `awk', since `awk' programs are generally I/O bound (i.e.  they
+spend most of their time doing input and output, instead of performing
+computations).
+
+   ---------- Footnotes ----------
+
+   (1) Some implementations of `awk' do not allow you to execute `next'
+from within a function body. Some other work-around will be necessary
+if you use such a version.
+
+
+File: gawk.info,  Node: Assert Function,  Next: Round Function,  Prev: Nextfile Function,  Up: Library Functions
+
+Assertions
+==========
+
+   When writing large programs, it is often useful to be able to know
+that a condition or set of conditions is true.  Before proceeding with a
+particular computation, you make a statement about what you believe to
+be the case.  Such a statement is known as an "assertion."  The C
+language provides an `<assert.h>' header file and corresponding
+`assert' macro that the programmer can use to make assertions.  If an
+assertion fails, the `assert' macro arranges to print a diagnostic
+message describing the condition that should have been true but was
+not, and then it kills the program.  In C, using `assert' looks this:
+
+     #include <assert.h>
+     
+     int myfunc(int a, double b)
+     {
+          assert(a <= 5 && b >= 17);
+          ...
+     }
+
+   If the assertion failed, the program would print a message similar to
+this:
+
+     prog.c:5: assertion failed: a <= 5 && b >= 17
+
+   The ANSI C language makes it possible to turn the condition into a
+string for use in printing the diagnostic message.  This is not
+possible in `awk', so this `assert' function also requires a string
+version of the condition that is being tested.
+
+     # assert --- assert that a condition is true. Otherwise exit.
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May, 1993
+     
+     function assert(condition, string)
+     {
+         if (! condition) {
+             printf("%s:%d: assertion failed: %s\n",
+                 FILENAME, FNR, string) > "/dev/stderr"
+             _assert_exit = 1
+             exit 1
+         }
+     }
+     
+     END {
+         if (_assert_exit)
+             exit 1
+     }
+
+   The `assert' function tests the `condition' parameter. If it is
+false, it prints a message to standard error, using the `string'
+parameter to describe the failed condition.  It then sets the variable
+`_assert_exit' to one, and executes the `exit' statement.  The `exit'
+statement jumps to the `END' rule. If the `END' rules finds
+`_assert_exit' to be true, then it exits immediately.
+
+   The purpose of the `END' rule with its test is to keep any other
+`END' rules from running.  When an assertion fails, the program should
+exit immediately.  If no assertions fail, then `_assert_exit' will
+still be false when the `END' rule is run normally, and the rest of the
+program's `END' rules will execute.  For all of this to work correctly,
+`assert.awk' must be the first source file read by `awk'.
+
+   You would use this function in your programs this way:
+
+     function myfunc(a, b)
+     {
+          assert(a <= 5 && b >= 17, "a <= 5 && b >= 17")
+          ...
+     }
+
+If the assertion failed, you would see a message like this:
+
+     mydata:1357: assertion failed: a <= 5 && b >= 17
+
+   There is a problem with this version of `assert', that it may not be
+possible to work around.  An `END' rule is automatically added to the
+program calling `assert'.  Normally, if a program consists of just a
+`BEGIN' rule, the input files and/or standard input are not read.
+However, now that the program has an `END' rule, `awk' will attempt to
+read the input data files, or standard input (*note Startup and Cleanup
+Actions: Using BEGIN/END.), most likely causing the program to hang,
+waiting for input.
+
+
+File: gawk.info,  Node: Round Function,  Next: Ordinal Functions,  Prev: Assert Function,  Up: Library Functions
+
+Rounding Numbers
+================
+
+   The way `printf' and `sprintf' (*note Using `printf' Statements for
+Fancier Printing: Printf.)  do rounding will often depend upon the
+system's C `sprintf' subroutine.  On many machines, `sprintf' rounding
+is "unbiased," which means it doesn't always round a trailing `.5' up,
+contrary to naive expectations.  In unbiased rounding, `.5' rounds to
+even, rather than always up, so 1.5 rounds to 2 but 4.5 rounds to 4.
+The result is that if you are using a format that does rounding (e.g.,
+`"%.0f"') you should check what your system does.  The following
+function does traditional rounding; it might be useful if your awk's
+`printf' does unbiased rounding.
+
+     # round --- do normal rounding
+     #
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, August, 1996
+     # Public Domain
+     
+     function round(x,   ival, aval, fraction)
+     {
+        ival = int(x)    # integer part, int() truncates
+     
+        # see if fractional part
+        if (ival == x)   # no fraction
+           return x
+     
+        if (x < 0) {
+           aval = -x     # absolute value
+           ival = int(aval)
+           fraction = aval - ival
+           if (fraction >= .5)
+              return int(x) - 1   # -2.5 --> -3
+           else
+              return int(x)       # -2.3 --> -2
+        } else {
+           fraction = x - ival
+           if (fraction >= .5)
+              return ival + 1
+           else
+              return ival
+        }
+     }
+     
+     # test harness
+     { print $0, round($0) }
+
+
+File: gawk.info,  Node: Ordinal Functions,  Next: Join Function,  Prev: Round Function,  Up: Library Functions
+
+Translating Between Characters and Numbers
+==========================================
+
+   One commercial implementation of `awk' supplies a built-in function,
+`ord', which takes a character and returns the numeric value for that
+character in the machine's character set.  If the string passed to
+`ord' has more than one character, only the first one is used.
+
+   The inverse of this function is `chr' (from the function of the same
+name in Pascal), which takes a number and returns the corresponding
+character.
+
+   Both functions can be written very nicely in `awk'; there is no real
+reason to build them into the `awk' interpreter.
+
+     # ord.awk --- do ord and chr
+     #
+     # Global identifiers:
+     #    _ord_:        numerical values indexed by characters
+     #    _ord_init:    function to initialize _ord_
+     #
+     # Arnold Robbins
+     # arnold@gnu.ai.mit.edu
+     # Public Domain
+     # 16 January, 1992
+     # 20 July, 1992, revised
+     
+     BEGIN    { _ord_init() }
+     
+     function _ord_init(    low, high, i, t)
+     {
+         low = sprintf("%c", 7) # BEL is ascii 7
+         if (low == "\a") {    # regular ascii
+             low = 0
+             high = 127
+         } else if (sprintf("%c", 128 + 7) == "\a") {
+             # ascii, mark parity
+             low = 128
+             high = 255
+         } else {        # ebcdic(!)
+             low = 0
+             high = 255
+         }
+     
+         for (i = low; i <= high; i++) {
+             t = sprintf("%c", i)
+             _ord_[t] = i
+         }
+     }
+
+   Some explanation of the numbers used by `chr' is worthwhile.  The
+most prominent character set in use today is ASCII. Although an
+eight-bit byte can hold 256 distinct values (from zero to 255), ASCII
+only defines characters that use the values from zero to 127.(1) At
+least one computer manufacturer that we know of uses ASCII, but with
+mark parity, meaning that the leftmost bit in the byte is always one.
+What this means is that on those systems, characters have numeric
+values from 128 to 255.  Finally, large mainframe systems use the
+EBCDIC character set, which uses all 256 values.  While there are other
+character sets in use on some older systems, they are not really worth
+worrying about.
+
+     function ord(str,    c)
+     {
+         # only first character is of interest
+         c = substr(str, 1, 1)
+         return _ord_[c]
+     }
+     
+     function chr(c)
+     {
+         # force c to be numeric by adding 0
+         return sprintf("%c", c + 0)
+     }
+     
+     #### test code ####
+     # BEGIN    \
+     # {
+     #    for (;;) {
+     #        printf("enter a character: ")
+     #        if (getline var <= 0)
+     #            break
+     #        printf("ord(%s) = %d\n", var, ord(var))
+     #    }
+     # }
+
+   An obvious improvement to these functions would be to move the code
+for the `_ord_init' function into the body of the `BEGIN' rule.  It was
+written this way initially for ease of development.
+
+   There is a "test program" in a `BEGIN' rule, for testing the
+function.  It is commented out for production use.
+
+   ---------- Footnotes ----------
+
+   (1) ASCII has been extended in many countries to use the values from
+128 to 255 for country-specific characters.  If your  system uses these
+extensions, you can simplify `_ord_init' to simply loop from zero to
+255.
+
+
+File: gawk.info,  Node: Join Function,  Next: Mktime Function,  Prev: Ordinal Functions,  Up: Library Functions
+
+Merging an Array Into a String
+==============================
+
+   When doing string processing, it is often useful to be able to join
+all the strings in an array into one long string.  The following
+function, `join', accomplishes this task.  It is used later in several
+of the application programs (*note Practical `awk' Programs: Sample
+Programs.).
+
+   Good function design is important; this function needs to be
+general, but it should also have a reasonable default behavior.  It is
+called with an array and the beginning and ending indices of the
+elements in the array to be merged.  This assumes that the array
+indices are numeric--a reasonable assumption since the array was likely
+created with `split' (*note Built-in Functions for String Manipulation:
+String Functions.).
+
+     # join.awk --- join an array into a string
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     function join(array, start, end, sep,    result, i)
+     {
+         if (sep == "")
+            sep = " "
+         else if (sep == SUBSEP) # magic value
+            sep = ""
+         result = array[start]
+         for (i = start + 1; i <= end; i++)
+             result = result sep array[i]
+         return result
+     }
+
+   An optional additional argument is the separator to use when joining
+the strings back together.  If the caller supplies a non-empty value,
+`join' uses it.  If it is not supplied, it will have a null value.  In
+this case, `join' uses a single blank as a default separator for the
+strings.  If the value is equal to `SUBSEP', then `join' joins the
+strings with no separator between them.  `SUBSEP' serves as a "magic"
+value to indicate that there should be no separation between the
+component strings.
+
+   It would be nice if `awk' had an assignment operator for
+concatenation.  The lack of an explicit operator for concatenation
+makes string operations more difficult than they really need to be.
+
+
+File: gawk.info,  Node: Mktime Function,  Next: Gettimeofday Function,  Prev: Join Function,  Up: Library Functions
+
+Turning Dates Into Timestamps
+=============================
+
+   The `systime' function built in to `gawk' returns the current time
+of day as a timestamp in "seconds since the Epoch."  This timestamp can
+be converted into a printable date of almost infinitely variable format
+using the built-in `strftime' function.  (For more information on
+`systime' and `strftime', *note Functions for Dealing with Time Stamps:
+Time Functions..)
+
+   An interesting but difficult problem is to convert a readable
+representation of a date back into a timestamp.  The ANSI C library
+provides a `mktime' function that does the basic job, converting a
+canonical representation of a date into a timestamp.
+
+   It would appear at first glance that `gawk' would have to supply a
+`mktime' built-in function that was simply a "hook" to the C language
+version.  In fact though, `mktime' can be implemented entirely in `awk'.
+
+   Here is a version of `mktime' for `awk'.  It takes a simple
+representation of the date and time, and converts it into a timestamp.
+
+   The code is presented here intermixed with explanatory prose.  In
+*Note Extracting Programs from Texinfo Source Files: Extract Program,
+you will see how the Texinfo source file for this Info file can be
+processed to extract the code into a single source file.
+
+   The program begins with a descriptive comment and a `BEGIN' rule
+that initializes a table `_tm_months'.  This table is a two-dimensional
+array that has the lengths of the months.  The first index is zero for
+regular years, and one for leap years.  The values are the same for all
+the months in both kinds of years, except for February; thus the use of
+multiple assignment.
+
+     # mktime.awk --- convert a canonical date representation
+     #                into a timestamp
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     BEGIN    \
+     {
+         # Initialize table of month lengths
+         _tm_months[0,1] = _tm_months[1,1] = 31
+         _tm_months[0,2] = 28; _tm_months[1,2] = 29
+         _tm_months[0,3] = _tm_months[1,3] = 31
+         _tm_months[0,4] = _tm_months[1,4] = 30
+         _tm_months[0,5] = _tm_months[1,5] = 31
+         _tm_months[0,6] = _tm_months[1,6] = 30
+         _tm_months[0,7] = _tm_months[1,7] = 31
+         _tm_months[0,8] = _tm_months[1,8] = 31
+         _tm_months[0,9] = _tm_months[1,9] = 30
+         _tm_months[0,10] = _tm_months[1,10] = 31
+         _tm_months[0,11] = _tm_months[1,11] = 30
+         _tm_months[0,12] = _tm_months[1,12] = 31
+     }
+
+   The benefit of merging multiple `BEGIN' rules (*note The `BEGIN' and
+`END' Special Patterns: BEGIN/END.)  is particularly clear when writing
+library files.  Functions in library files can cleanly initialize their
+own private data and also provide clean-up actions in private `END'
+rules.
+
+   The next function is a simple one that computes whether a given year
+is or is not a leap year.  If a year is evenly divisible by four, but
+not evenly divisible by 100, or if it is evenly divisible by 400, then
+it is a leap year.  Thus, 1904 was a leap year, 1900 was not, but 2000
+will be.
+
+     # decide if a year is a leap year
+     function _tm_isleap(year,    ret)
+     {
+         ret = (year % 4 == 0 && year % 100 != 0) ||
+                 (year % 400 == 0)
+     
+         return ret
+     }
+
+   This function is only used a few times in this file, and its
+computation could have been written "in-line" (at the point where it's
+used).  Making it a separate function made the original development
+easier, and also avoids the possibility of typing errors when
+duplicating the code in multiple places.
+
+   The next function is more interesting.  It does most of the work of
+generating a timestamp, which is converting a date and time into some
+number of seconds since the Epoch.  The caller passes an array (rather
+imaginatively named `a') containing six values: the year including
+century, the month as a number between one and 12, the day of the
+month, the hour as a number between zero and 23, the minute in the
+hour, and the seconds within the minute.
+
+   The function uses several local variables to precompute the number of
+seconds in an hour, seconds in a day, and seconds in a year.  Often,
+similar C code simply writes out the expression in-line, expecting the
+compiler to do "constant folding".  E.g., most C compilers would turn
+`60 * 60' into `3600' at compile time, instead of recomputing it every
+time at run time.  Precomputing these values makes the function more
+efficient.
+
+     # convert a date into seconds
+     function _tm_addup(a,    total, yearsecs, daysecs,
+                              hoursecs, i, j)
+     {
+         hoursecs = 60 * 60
+         daysecs = 24 * hoursecs
+         yearsecs = 365 * daysecs
+     
+         total = (a[1] - 1970) * yearsecs
+     
+         # extra day for leap years
+         for (i = 1970; i < a[1]; i++)
+             if (_tm_isleap(i))
+                 total += daysecs
+     
+         j = _tm_isleap(a[1])
+         for (i = 1; i < a[2]; i++)
+             total += _tm_months[j, i] * daysecs
+     
+         total += (a[3] - 1) * daysecs
+         total += a[4] * hoursecs
+         total += a[5] * 60
+         total += a[6]
+     
+         return total
+     }
+
+   The function starts with a first approximation of all the seconds
+between Midnight, January 1, 1970,(1) and the beginning of the current
+year.  It then goes through all those years, and for every leap year,
+adds an additional day's worth of seconds.
+
+   The variable `j' holds either one or zero, if the current year is or
+is not a leap year.  For every month in the current year prior to the
+current month, it adds the number of seconds in the month, using the
+appropriate entry in the `_tm_months' array.
+
+   Finally, it adds in the seconds for the number of days prior to the
+current day, and the number of hours, minutes, and seconds in the
+current day.
+
+   The result is a count of seconds since January 1, 1970.  This value
+is not yet what is needed though.  The reason why is described shortly.
+
+   The main `mktime' function takes a single character string argument.
+This string is a representation of a date and time in a "canonical"
+(fixed) form.  This string should be `"YEAR MONTH DAY HOUR MINUTE
+SECOND"'.
+
+     # mktime --- convert a date into seconds,
+     #            compensate for time zone
+     
+     function mktime(str,    res1, res2, a, b, i, j, t, diff)
+     {
+         i = split(str, a, " ")    # don't rely on FS
+     
+         if (i != 6)
+             return -1
+     
+         # force numeric
+         for (j in a)
+             a[j] += 0
+     
+         # validate
+         if (a[1] < 1970 ||
+             a[2] < 1 || a[2] > 12 ||
+             a[3] < 1 || a[3] > 31 ||
+             a[4] < 0 || a[4] > 23 ||
+             a[5] < 0 || a[5] > 59 ||
+             a[6] < 0 || a[6] > 60 )
+                 return -1
+     
+         res1 = _tm_addup(a)
+         t = strftime("%Y %m %d %H %M %S", res1)
+     
+         if (_tm_debug)
+             printf("(%s) -> (%s)\n", str, t) > "/dev/stderr"
+     
+         split(t, b, " ")
+         res2 = _tm_addup(b)
+     
+         diff = res1 - res2
+     
+         if (_tm_debug)
+             printf("diff = %d seconds\n", diff) > "/dev/stderr"
+     
+         res1 += diff
+     
+         return res1
+     }
+
+   The function first splits the string into an array, using spaces and
+tabs as separators.  If there are not six elements in the array, it
+returns an error, signaled as the value -1.  Next, it forces each
+element of the array to be numeric, by adding zero to it.  The
+following `if' statement then makes sure that each element is within an
+allowable range.  (This checking could be extended further, e.g., to
+make sure that the day of the month is within the correct range for the
+particular month supplied.)  All of this is essentially preliminary
+set-up and error checking.
+
+   Recall that `_tm_addup' generated a value in seconds since Midnight,
+January 1, 1970.  This value is not directly usable as the result we
+want, _since the calculation does not account for the local timezone_.
+In other words, the value represents the count in seconds since the
+Epoch, but only for UTC (Universal Coordinated Time).  If the local
+timezone is east or west of UTC, then some number of hours should be
+either added to, or subtracted from the resulting timestamp.
+
+   For example, 6:23 p.m. in Atlanta, Georgia (USA), is normally five
+hours west of (behind) UTC.  It is only four hours behind UTC if
+daylight savings time is in effect.  If you are calling `mktime' in
+Atlanta, with the argument `"1993 5 23 18 23 12"', the result from
+`_tm_addup' will be for 6:23 p.m. UTC, which is only 2:23 p.m. in
+Atlanta.  It is necessary to add another four hours worth of seconds to
+the result.
+
+   How can `mktime' determine how far away it is from UTC?  This is
+surprisingly easy.  The returned timestamp represents the time passed to
+`mktime' _as UTC_.  This timestamp can be fed back to `strftime', which
+will format it as a _local_ time; i.e. as if it already had the UTC
+difference added in to it.  This is done by giving
+`"%Y %m %d %H %M %S"' to `strftime' as the format argument.  It returns
+the computed timestamp in the original string format.  The result
+represents a time that accounts for the UTC difference.  When the new
+time is converted back to a timestamp, the difference between the two
+timestamps is the difference (in seconds) between the local timezone
+and UTC.  This difference is then added back to the original result.
+An example demonstrating this is presented below.
+
+   Finally, there is a "main" program for testing the function.
+
+     BEGIN  {
+         if (_tm_test) {
+             printf "Enter date as yyyy mm dd hh mm ss: "
+             getline _tm_test_date
+     
+             t = mktime(_tm_test_date)
+             r = strftime("%Y %m %d %H %M %S", t)
+             printf "Got back (%s)\n", r
+         }
+     }
+
+   The entire program uses two variables that can be set on the command
+line to control debugging output and to enable the test in the final
+`BEGIN' rule.  Here is the result of a test run. (Note that debugging
+output is to standard error, and test output is to standard output.)
+
+     $ gawk -f mktime.awk -v _tm_test=1 -v _tm_debug=1
+     -| Enter date as yyyy mm dd hh mm ss: 1993 5 23 15 35 10
+     error--> (1993 5 23 15 35 10) -> (1993 05 23 11 35 10)
+     error--> diff = 14400 seconds
+     -| Got back (1993 05 23 15 35 10)
+
+   The time entered was 3:35 p.m. (15:35 on a 24-hour clock), on May
+23, 1993.  The first line of debugging output shows the resulting time
+as UTC--four hours ahead of the local time zone.  The second line shows
+that the difference is 14400 seconds, which is four hours.  (The
+difference is only four hours, since daylight savings time is in effect
+during May.)  The final line of test output shows that the timezone
+compensation algorithm works; the returned time is the same as the
+entered time.
+
+   This program does not solve the general problem of turning an
+arbitrary date representation into a timestamp.  That problem is very
+involved.  However, the `mktime' function provides a foundation upon
+which to build. Other software can convert month names into numeric
+months, and AM/PM times into 24-hour clocks, to generate the
+"canonical" format that `mktime' requires.
+
+   ---------- Footnotes ----------
+
+   (1) This is the Epoch on POSIX systems.  It may be different on
+other systems.
+
+
+File: gawk.info,  Node: Gettimeofday Function,  Next: Filetrans Function,  Prev: Mktime Function,  Up: Library Functions
+
+Managing the Time of Day
+========================
+
+   The `systime' and `strftime' functions described in *Note Functions
+for Dealing with Time Stamps: Time Functions, provide the minimum
+functionality necessary for dealing with the time of day in human
+readable form.  While `strftime' is extensive, the control formats are
+not necessarily easy to remember or intuitively obvious when reading a
+program.
+
+   The following function, `gettimeofday', populates a user-supplied
+array with pre-formatted time information.  It returns a string with
+the current time formatted in the same way as the `date' utility.
+
+     # gettimeofday --- get the time of day in a usable format
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain, May 1993
+     #
+     # Returns a string in the format of output of date(1)
+     # Populates the array argument time with individual values:
+     #    time["second"]       -- seconds (0 - 59)
+     #    time["minute"]       -- minutes (0 - 59)
+     #    time["hour"]         -- hours (0 - 23)
+     #    time["althour"]      -- hours (0 - 12)
+     #    time["monthday"]     -- day of month (1 - 31)
+     #    time["month"]        -- month of year (1 - 12)
+     #    time["monthname"]    -- name of the month
+     #    time["shortmonth"]   -- short name of the month
+     #    time["year"]         -- year within century (0 - 99)
+     #    time["fullyear"]     -- year with century (19xx or 20xx)
+     #    time["weekday"]      -- day of week (Sunday = 0)
+     #    time["altweekday"]   -- day of week (Monday = 0)
+     #    time["weeknum"]      -- week number, Sunday first day
+     #    time["altweeknum"]   -- week number, Monday first day
+     #    time["dayname"]      -- name of weekday
+     #    time["shortdayname"] -- short name of weekday
+     #    time["yearday"]      -- day of year (0 - 365)
+     #    time["timezone"]     -- abbreviation of timezone name
+     #    time["ampm"]         -- AM or PM designation
+     
+     function gettimeofday(time,    ret, now, i)
+     {
+         # get time once, avoids unnecessary system calls
+         now = systime()
+     
+         # return date(1)-style output
+         ret = strftime("%a %b %d %H:%M:%S %Z %Y", now)
+     
+         # clear out target array
+         for (i in time)
+             delete time[i]
+     
+         # fill in values, force numeric values to be
+         # numeric by adding 0
+         time["second"]       = strftime("%S", now) + 0
+         time["minute"]       = strftime("%M", now) + 0
+         time["hour"]         = strftime("%H", now) + 0
+         time["althour"]      = strftime("%I", now) + 0
+         time["monthday"]     = strftime("%d", now) + 0
+         time["month"]        = strftime("%m", now) + 0
+         time["monthname"]    = strftime("%B", now)
+         time["shortmonth"]   = strftime("%b", now)
+         time["year"]         = strftime("%y", now) + 0
+         time["fullyear"]     = strftime("%Y", now) + 0
+         time["weekday"]      = strftime("%w", now) + 0
+         time["altweekday"]   = strftime("%u", now) + 0
+         time["dayname"]      = strftime("%A", now)
+         time["shortdayname"] = strftime("%a", now)
+         time["yearday"]      = strftime("%j", now) + 0
+         time["timezone"]     = strftime("%Z", now)
+         time["ampm"]         = strftime("%p", now)
+         time["weeknum"]      = strftime("%U", now) + 0
+         time["altweeknum"]   = strftime("%W", now) + 0
+     
+         return ret
+     }
+
+   The string indices are easier to use and read than the various
+formats required by `strftime'.  The `alarm' program presented in *Note
+An Alarm Clock Program: Alarm Program, uses this function.
+
+   The `gettimeofday' function is presented above as it was written. A
+more general design for this function would have allowed the user to
+supply an optional timestamp value that would have been used instead of
+the current time.
+
+
+File: gawk.info,  Node: Filetrans Function,  Next: Getopt Function,  Prev: Gettimeofday Function,  Up: Library Functions
+
+Noting Data File Boundaries
+===========================
+
+   The `BEGIN' and `END' rules are each executed exactly once, at the
+beginning and end respectively of your `awk' program (*note The `BEGIN'
+and `END' Special Patterns: BEGIN/END.).  We (the `gawk' authors) once
+had a user who mistakenly thought that the `BEGIN' rule was executed at
+the beginning of each data file and the `END' rule was executed at the
+end of each data file.  When informed that this was not the case, the
+user requested that we add new special patterns to `gawk', named
+`BEGIN_FILE' and `END_FILE', that would have the desired behavior.  He
+even supplied us the code to do so.
+
+   However, after a little thought, I came up with the following
+library program.  It arranges to call two user-supplied functions,
+`beginfile' and `endfile', at the beginning and end of each data file.
+Besides solving the problem in only nine(!) lines of code, it does so
+_portably_; this will work with any implementation of `awk'.
+
+     # transfile.awk
+     #
+     # Give the user a hook for filename transitions
+     #
+     # The user must supply functions beginfile() and endfile()
+     # that each take the name of the file being started or
+     # finished, respectively.
+     #
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, January 1992
+     # Public Domain
+     
+     FILENAME != _oldfilename \
+     {
+         if (_oldfilename != "")
+             endfile(_oldfilename)
+         _oldfilename = FILENAME
+         beginfile(FILENAME)
+     }
+     
+     END   { endfile(FILENAME) }
+
+   This file must be loaded before the user's "main" program, so that
+the rule it supplies will be executed first.
+
+   This rule relies on `awk''s `FILENAME' variable that automatically
+changes for each new data file.  The current file name is saved in a
+private variable, `_oldfilename'.  If `FILENAME' does not equal
+`_oldfilename', then a new data file is being processed, and it is
+necessary to call `endfile' for the old file.  Since `endfile' should
+only be called if a file has been processed, the program first checks
+to make sure that `_oldfilename' is not the null string.  The program
+then assigns the current file name to `_oldfilename', and calls
+`beginfile' for the file.  Since, like all `awk' variables,
+`_oldfilename' will be initialized to the null string, this rule
+executes correctly even for the first data file.
+
+   The program also supplies an `END' rule, to do the final processing
+for the last file.  Since this `END' rule comes before any `END' rules
+supplied in the "main" program, `endfile' will be called first.  Once
+again the value of multiple `BEGIN' and `END' rules should be clear.
+
+   This version has same problem as the first version of `nextfile'
+(*note Implementing `nextfile' as a Function: Nextfile Function.).  If
+the same data file occurs twice in a row on command line, then
+`endfile' and `beginfile' will not be executed at the end of the first
+pass and at the beginning of the second pass.  This version solves the
+problem.
+
+     # ftrans.awk --- handle data file transitions
+     #
+     # user supplies beginfile() and endfile() functions
+     #
+     # Arnold Robbins, arnold@gnu.ai.mit.edu. November 1992
+     # Public Domain
+     
+     FNR == 1 {
+         if (_filename_ != "")
+             endfile(_filename_)
+         _filename_ = FILENAME
+         beginfile(FILENAME)
+     }
+     
+     END  { endfile(_filename_) }
+
+   In *Note Counting Things: Wc Program, you will see how this library
+function can be used, and how it simplifies writing the main program.
+
+
+File: gawk.info,  Node: Getopt Function,  Next: Passwd Functions,  Prev: Filetrans Function,  Up: Library Functions
+
+Processing Command Line Options
+===============================
+
+   Most utilities on POSIX compatible systems take options or
+"switches" on the command line that can be used to change the way a
+program behaves.  `awk' is an example of such a program (*note Command
+Line Options: Options.).  Often, options take "arguments", data that
+the program needs to correctly obey the command line option.  For
+example, `awk''s `-F' option requires a string to use as the field
+separator.  The first occurrence on the command line of either `--' or a
+string that does not begin with `-' ends the options.
+
+   Most Unix systems provide a C function named `getopt' for processing
+command line arguments.  The programmer provides a string describing
+the one letter options. If an option requires an argument, it is
+followed in the string with a colon.  `getopt' is also passed the count
+and values of the command line arguments, and is called in a loop.
+`getopt' processes the command line arguments for option letters.  Each
+time around the loop, it returns a single character representing the
+next option letter that it found, or `?' if it found an invalid option.
+When it returns -1, there are no options left on the command line.
+
+   When using `getopt', options that do not take arguments can be
+grouped together.  Furthermore, options that take arguments require
+that the argument be present.  The argument can immediately follow the
+option letter, or it can be a separate command line argument.
+
+   Given a hypothetical program that takes three command line options,
+`-a', `-b', and `-c', and `-b' requires an argument, all of the
+following are valid ways of invoking the program:
+
+     prog -a -b foo -c data1 data2 data3
+     prog -ac -bfoo -- data1 data2 data3
+     prog -acbfoo data1 data2 data3
+
+   Notice that when the argument is grouped with its option, the rest of
+the command line argument is considered to be the option's argument.
+In the above example, `-acbfoo' indicates that all of the `-a', `-b',
+and `-c' options were supplied, and that `foo' is the argument to the
+`-b' option.
+
+   `getopt' provides four external variables that the programmer can
+use.
+
+`optind'
+     The index in the argument value array (`argv') where the first
+     non-option command line argument can be found.
+
+`optarg'
+     The string value of the argument to an option.
+
+`opterr'
+     Usually `getopt' prints an error message when it finds an invalid
+     option.  Setting `opterr' to zero disables this feature.  (An
+     application might wish to print its own error message.)
+
+`optopt'
+     The letter representing the command line option.  While not
+     usually documented, most versions supply this variable.
+
+   The following C fragment shows how `getopt' might process command
+line arguments for `awk'.
+
+     int
+     main(int argc, char *argv[])
+     {
+         ...
+         /* print our own message */
+         opterr = 0;
+         while ((c = getopt(argc, argv, "v:f:F:W:")) != -1) {
+             switch (c) {
+             case 'f':    /* file */
+                 ...
+                 break;
+             case 'F':    /* field separator */
+                 ...
+                 break;
+             case 'v':    /* variable assignment */
+                 ...
+                 break;
+             case 'W':    /* extension */
+                 ...
+                 break;
+             case '?':
+             default:
+                 usage();
+                 break;
+             }
+         }
+         ...
+     }
+
+   As a side point, `gawk' actually uses the GNU `getopt_long' function
+to process both normal and GNU-style long options (*note Command Line
+Options: Options.).
+
+   The abstraction provided by `getopt' is very useful, and would be
+quite handy in `awk' programs as well.  Here is an `awk' version of
+`getopt'.  This function highlights one of the greatest weaknesses in
+`awk', which is that it is very poor at manipulating single characters.
+Repeated calls to `substr' are necessary for accessing individual
+characters (*note Built-in Functions for String Manipulation: String
+Functions.).
+
+   The discussion walks through the code a bit at a time.
+
+     # getopt --- do C library getopt(3) function in awk
+     #
+     # arnold@gnu.ai.mit.edu
+     # Public domain
+     #
+     # Initial version: March, 1991
+     # Revised: May, 1993
+     
+     # External variables:
+     #    Optind -- index of ARGV for first non-option argument
+     #    Optarg -- string value of argument to current option
+     #    Opterr -- if non-zero, print our own diagnostic
+     #    Optopt -- current option letter
+     
+     # Returns
+     #    -1     at end of options
+     #    ?      for unrecognized option
+     #    <c>    a character representing the current option
+     
+     # Private Data
+     #    _opti  index in multi-flag option, e.g., -abc
+
+   The function starts out with some documentation: who wrote the code,
+and when it was revised, followed by a list of the global variables it
+uses, what the return values are and what they mean, and any global
+variables that are "private" to this library function.  Such
+documentation is essential for any program, and particularly for
+library functions.
+
+     function getopt(argc, argv, options,    optl, thisopt, i)
+     {
+         optl = length(options)
+         if (optl == 0)        # no options given
+             return -1
+     
+         if (argv[Optind] == "--") {  # all done
+             Optind++
+             _opti = 0
+             return -1
+         } else if (argv[Optind] !~ /^-[^: \t\n\f\r\v\b]/) {
+             _opti = 0
+             return -1
+         }
+
+   The function first checks that it was indeed called with a string of
+options (the `options' parameter).  If `options' has a zero length,
+`getopt' immediately returns -1.
+
+   The next thing to check for is the end of the options.  A `--' ends
+the command line options, as does any command line argument that does
+not begin with a `-'.  `Optind' is used to step through the array of
+command line arguments; it retains its value across calls to `getopt',
+since it is a global variable.
+
+   The regexp used, `/^-[^: \t\n\f\r\v\b]/', is perhaps a bit of
+overkill; it checks for a `-' followed by anything that is not
+whitespace and not a colon.  If the current command line argument does
+not match this pattern, it is not an option, and it ends option
+processing.
+
+         if (_opti == 0)
+             _opti = 2
+         thisopt = substr(argv[Optind], _opti, 1)
+         Optopt = thisopt
+         i = index(options, thisopt)
+         if (i == 0) {
+             if (Opterr)
+                 printf("%c -- invalid option\n",
+                                       thisopt) > "/dev/stderr"
+             if (_opti >= length(argv[Optind])) {
+                 Optind++
+                 _opti = 0
+             } else
+                 _opti++
+             return "?"
+         }
+
+   The `_opti' variable tracks the position in the current command line
+argument (`argv[Optind]').  In the case that multiple options were
+grouped together with one `-' (e.g., `-abx'), it is necessary to return
+them to the user one at a time.
+
+   If `_opti' is equal to zero, it is set to two, the index in the
+string of the next character to look at (we skip the `-', which is at
+position one).  The variable `thisopt' holds the character, obtained
+with `substr'.  It is saved in `Optopt' for the main program to use.
+
+   If `thisopt' is not in the `options' string, then it is an invalid
+option.  If `Opterr' is non-zero, `getopt' prints an error message on
+the standard error that is similar to the message from the C version of
+`getopt'.
+
+   Since the option is invalid, it is necessary to skip it and move on
+to the next option character.  If `_opti' is greater than or equal to
+the length of the current command line argument, then it is necessary
+to move on to the next one, so `Optind' is incremented and `_opti' is
+reset to zero. Otherwise, `Optind' is left alone and `_opti' is merely
+incremented.
+
+   In any case, since the option was invalid, `getopt' returns `?'.
+The main program can examine `Optopt' if it needs to know what the
+invalid option letter actually was.
+
+         if (substr(options, i + 1, 1) == ":") {
+             # get option argument
+             if (length(substr(argv[Optind], _opti + 1)) > 0)
+                 Optarg = substr(argv[Optind], _opti + 1)
+             else
+                 Optarg = argv[++Optind]
+             _opti = 0
+         } else
+             Optarg = ""
+
+   If the option requires an argument, the option letter is followed by
+a colon in the `options' string.  If there are remaining characters in
+the current command line argument (`argv[Optind]'), then the rest of
+that string is assigned to `Optarg'.  Otherwise, the next command line
+argument is used (`-xFOO' vs. `-x FOO'). In either case, `_opti' is
+reset to zero, since there are no more characters left to examine in
+the current command line argument.
+
+         if (_opti == 0 || _opti >= length(argv[Optind])) {
+             Optind++
+             _opti = 0
+         } else
+             _opti++
+         return thisopt
+     }
+
+   Finally, if `_opti' is either zero or greater than the length of the
+current command line argument, it means this element in `argv' is
+through being processed, so `Optind' is incremented to point to the
+next element in `argv'.  If neither condition is true, then only
+`_opti' is incremented, so that the next option letter can be processed
+on the next call to `getopt'.
+
+     BEGIN {
+         Opterr = 1    # default is to diagnose
+         Optind = 1    # skip ARGV[0]
+     
+         # test program
+         if (_getopt_test) {
+             while ((_go_c = getopt(ARGC, ARGV, "ab:cd")) != -1)
+                 printf("c = <%c>, optarg = <%s>\n",
+                                            _go_c, Optarg)
+             printf("non-option arguments:\n")
+             for (; Optind < ARGC; Optind++)
+                 printf("\tARGV[%d] = <%s>\n",
+                                         Optind, ARGV[Optind])
+         }
+     }
+
+   The `BEGIN' rule initializes both `Opterr' and `Optind' to one.
+`Opterr' is set to one, since the default behavior is for `getopt' to
+print a diagnostic message upon seeing an invalid option.  `Optind' is
+set to one, since there's no reason to look at the program name, which
+is in `ARGV[0]'.
+
+   The rest of the `BEGIN' rule is a simple test program.  Here is the
+result of two sample runs of the test program.
+
+     $ awk -f getopt.awk -v _getopt_test=1 -- -a -cbARG bax -x
+     -| c = <a>, optarg = <>
+     -| c = <c>, optarg = <>
+     -| c = <b>, optarg = <ARG>
+     -| non-option arguments:
+     -|         ARGV[3] = <bax>
+     -|         ARGV[4] = <-x>
+     
+     $ awk -f getopt.awk -v _getopt_test=1 -- -a -x -- xyz abc
+     -| c = <a>, optarg = <>
+     error--> x -- invalid option
+     -| c = <?>, optarg = <>
+     -| non-option arguments:
+     -|         ARGV[4] = <xyz>
+     -|         ARGV[5] = <abc>
+
+   The first `--' terminates the arguments to `awk', so that it does
+not try to interpret the `-a' etc. as its own options.
+
+   Several of the sample programs presented in *Note Practical `awk'
+Programs: Sample Programs, use `getopt' to process their arguments.
+
+
+File: gawk.info,  Node: Passwd Functions,  Next: Group Functions,  Prev: Getopt Function,  Up: Library Functions
+
+Reading the User Database
+=========================
+
+   The `/dev/user' special file (*note Special File Names in `gawk':
+Special Files.)  provides access to the current user's real and
+effective user and group id numbers, and if available, the user's
+supplementary group set.  However, since these are numbers, they do not
+provide very useful information to the average user.  There needs to be
+some way to find the user information associated with the user and
+group numbers.  This section presents a suite of functions for
+retrieving information from the user database.  *Note Reading the Group
+Database: Group Functions, for a similar suite that retrieves
+information from the group database.
+
+   The POSIX standard does not define the file where user information is
+kept.  Instead, it provides the `<pwd.h>' header file and several C
+language subroutines for obtaining user information.  The primary
+function is `getpwent', for "get password entry."  The "password" comes
+from the original user database file, `/etc/passwd', which kept user
+information, along with the encrypted passwords (hence the name).
+
+   While an `awk' program could simply read `/etc/passwd' directly (the
+format is well known), because of the way password files are handled on
+networked systems, this file may not contain complete information about
+the system's set of users.
+
+   To be sure of being able to produce a readable, complete version of
+the user database, it is necessary to write a small C program that
+calls `getpwent'.  `getpwent' is defined to return a pointer to a
+`struct passwd'.  Each time it is called, it returns the next entry in
+the database.  When there are no more entries, it returns `NULL', the
+null pointer.  When this happens, the C program should call `endpwent'
+to close the database.  Here is `pwcat', a C program that "cats" the
+password database.
+
+     /*
+      * pwcat.c
+      *
+      * Generate a printable version of the password database
+      *
+      * Arnold Robbins
+      * arnold@gnu.ai.mit.edu
+      * May 1993
+      * Public Domain
+      */
+     
+     #include <stdio.h>
+     #include <pwd.h>
+     
+     int
+     main(argc, argv)
+     int argc;
+     char **argv;
+     {
+         struct passwd *p;
+     
+         while ((p = getpwent()) != NULL)
+             printf("%s:%s:%d:%d:%s:%s:%s\n",
+                 p->pw_name, p->pw_passwd, p->pw_uid,
+                 p->pw_gid, p->pw_gecos, p->pw_dir, p->pw_shell);
+     
+         endpwent();
+         exit(0);
+     }
+
+   If you don't understand C, don't worry about it.  The output from
+`pwcat' is the user database, in the traditional `/etc/passwd' format
+of colon-separated fields.  The fields are:
+
+Login name
+     The user's login name.
+
+Encrypted password
+     The user's encrypted password.  This may not be available on some
+     systems.
+
+User-ID
+     The user's numeric user-id number.
+
+Group-ID
+     The user's numeric group-id number.
+
+Full name
+     The user's full name, and perhaps other information associated
+     with the user.
+
+Home directory
+     The user's login, or "home" directory (familiar to shell
+     programmers as `$HOME').
+
+Login shell
+     The program that will be run when the user logs in.  This is
+     usually a shell, such as Bash (the Gnu Bourne-Again shell).
+
+   Here are a few lines representative of `pwcat''s output.
+
+     $ pwcat
+     -| root:3Ov02d5VaUPB6:0:1:Operator:/:/bin/sh
+     -| nobody:*:65534:65534::/:
+     -| daemon:*:1:1::/:
+     -| sys:*:2:2::/:/bin/csh
+     -| bin:*:3:3::/bin:
+     -| arnold:xyzzy:2076:10:Arnold Robbins:/home/arnold:/bin/sh
+     -| miriam:yxaay:112:10:Miriam Robbins:/home/miriam:/bin/sh
+     -| andy:abcca2:113:10:Andy Jacobs:/home/andy:/bin/sh
+     ...
+
+   With that introduction, here is a group of functions for getting user
+information.  There are several functions here, corresponding to the C
+functions of the same name.
+
+     # passwd.awk --- access password file information
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     BEGIN {
+         # tailor this to suit your system
+         _pw_awklib = "/usr/local/libexec/awk/"
+     }
+     
+     function _pw_init(    oldfs, oldrs, olddol0, pwcat)
+     {
+         if (_pw_inited)
+             return
+         oldfs = FS
+         oldrs = RS
+         olddol0 = $0
+         FS = ":"
+         RS = "\n"
+         pwcat = _pw_awklib "pwcat"
+         while ((pwcat | getline) > 0) {
+             _pw_byname[$1] = $0
+             _pw_byuid[$3] = $0
+             _pw_bycount[++_pw_total] = $0
+         }
+         close(pwcat)
+         _pw_count = 0
+         _pw_inited = 1
+         FS = oldfs
+         RS = oldrs
+         $0 = olddol0
+     }
+
+   The `BEGIN' rule sets a private variable to the directory where
+`pwcat' is stored.  Since it is used to help out an `awk' library
+routine, we have chosen to put it in `/usr/local/libexec/awk'.  You
+might want it to be in a different directory on your system.
+
+   The function `_pw_init' keeps three copies of the user information
+in three associative arrays.  The arrays are indexed by user name
+(`_pw_byname'), by user-id number (`_pw_byuid'), and by order of
+occurrence (`_pw_bycount').
+
+   The variable `_pw_inited' is used for efficiency; `_pw_init' only
+needs to be called once.
+
+   Since this function uses `getline' to read information from `pwcat',
+it first saves the values of `FS', `RS', and `$0'.  Doing so is
+necessary, since these functions could be called from anywhere within a
+user's program, and the user may have his or her own values for `FS'
+and `RS'.
+
+   The main part of the function uses a loop to read database lines,
+split the line into fields, and then store the line into each array as
+necessary.  When the loop is done, `_pw_init' cleans up by closing the
+pipeline, setting `_pw_inited' to one, and restoring `FS', `RS', and
+`$0'.  The use of `_pw_count' will be explained below.
+
+     function getpwnam(name)
+     {
+         _pw_init()
+         if (name in _pw_byname)
+             return _pw_byname[name]
+         return ""
+     }
+
+   The `getpwnam' function takes a user name as a string argument. If
+that user is in the database, it returns the appropriate line.
+Otherwise it returns the null string.
+
+     function getpwuid(uid)
+     {
+         _pw_init()
+         if (uid in _pw_byuid)
+             return _pw_byuid[uid]
+         return ""
+     }
+
+   Similarly, the `getpwuid' function takes a user-id number argument.
+If that user number is in the database, it returns the appropriate
+line. Otherwise it returns the null string.
+
+     function getpwent()
+     {
+         _pw_init()
+         if (_pw_count < _pw_total)
+             return _pw_bycount[++_pw_count]
+         return ""
+     }
+
+   The `getpwent' function simply steps through the database, one entry
+at a time.  It uses `_pw_count' to track its current position in the
+`_pw_bycount' array.
+
+     function endpwent()
+     {
+         _pw_count = 0
+     }
+
+   The `endpwent' function resets `_pw_count' to zero, so that
+subsequent calls to `getpwent' will start over again.
+
+   A conscious design decision in this suite is that each subroutine
+calls `_pw_init' to initialize the database arrays.  The overhead of
+running a separate process to generate the user database, and the I/O
+to scan it, will only be incurred if the user's main program actually
+calls one of these functions.  If this library file is loaded along
+with a user's program, but none of the routines are ever called, then
+there is no extra run-time overhead.  (The alternative would be to move
+the body of `_pw_init' into a `BEGIN' rule, which would always run
+`pwcat'.  This simplifies the code but runs an extra process that may
+never be needed.)
+
+   In turn, calling `_pw_init' is not too expensive, since the
+`_pw_inited' variable keeps the program from reading the data more than
+once.  If you are worried about squeezing every last cycle out of your
+`awk' program, the check of `_pw_inited' could be moved out of
+`_pw_init' and duplicated in all the other functions.  In practice,
+this is not necessary, since most `awk' programs are I/O bound, and it
+would clutter up the code.
+
+   The `id' program in *Note Printing Out User Information: Id Program,
+uses these functions.
+
+
+File: gawk.info,  Node: Group Functions,  Next: Library Names,  Prev: Passwd Functions,  Up: Library Functions
+
+Reading the Group Database
+==========================
+
+   Much of the discussion presented in *Note Reading the User Database:
+Passwd Functions, applies to the group database as well.  Although
+there has traditionally been a well known file, `/etc/group', in a well
+known format, the POSIX standard only provides a set of C library
+routines (`<grp.h>' and `getgrent') for accessing the information.
+Even though this file may exist, it likely does not have complete
+information.  Therefore, as with the user database, it is necessary to
+have a small C program that generates the group database as its output.
+
+   Here is `grcat', a C program that "cats" the group database.
+
+     /*
+      * grcat.c
+      *
+      * Generate a printable version of the group database
+      *
+      * Arnold Robbins, arnold@gnu.ai.mit.edu
+      * May 1993
+      * Public Domain
+      */
+     
+     #include <stdio.h>
+     #include <grp.h>
+     
+     int
+     main(argc, argv)
+     int argc;
+     char **argv;
+     {
+         struct group *g;
+         int i;
+     
+         while ((g = getgrent()) != NULL) {
+             printf("%s:%s:%d:", g->gr_name, g->gr_passwd,
+                                                 g->gr_gid);
+             for (i = 0; g->gr_mem[i] != NULL; i++) {
+                 printf("%s", g->gr_mem[i]);
+                 if (g->gr_mem[i+1] != NULL)
+                     putchar(',');
+             }
+             putchar('\n');
+         }
+         endgrent();
+         exit(0);
+     }
+
+   Each line in the group database represent one group.  The fields are
+separated with colons, and represent the following information.
+
+Group Name
+     The name of the group.
+
+Group Password
+     The encrypted group password. In practice, this field is never
+     used. It is usually empty, or set to `*'.
+
+Group ID Number
+     The numeric group-id number. This number should be unique within
+     the file.
+
+Group Member List
+     A comma-separated list of user names.  These users are members of
+     the group.  Most Unix systems allow users to be members of several
+     groups simultaneously.  If your system does, then reading
+     `/dev/user' will return those group-id numbers in `$5' through
+     `$NF'.  (Note that `/dev/user' is a `gawk' extension; *note
+     Special File Names in `gawk': Special Files..)
+
+   Here is what running `grcat' might produce:
+
+     $ grcat
+     -| wheel:*:0:arnold
+     -| nogroup:*:65534:
+     -| daemon:*:1:
+     -| kmem:*:2:
+     -| staff:*:10:arnold,miriam,andy
+     -| other:*:20:
+     ...
+
+   Here are the functions for obtaining information from the group
+database.  There are several, modeled after the C library functions of
+the same names.
+
+     # group.awk --- functions for dealing with the group file
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     BEGIN    \
+     {
+         # Change to suit your system
+         _gr_awklib = "/usr/local/libexec/awk/"
+     }
+     
+     function _gr_init(    oldfs, oldrs, olddol0, grcat, n, a, i)
+     {
+         if (_gr_inited)
+             return
+     
+         oldfs = FS
+         oldrs = RS
+         olddol0 = $0
+         FS = ":"
+         RS = "\n"
+     
+         grcat = _gr_awklib "grcat"
+         while ((grcat | getline) > 0) {
+             if ($1 in _gr_byname)
+                 _gr_byname[$1] = _gr_byname[$1] "," $4
+             else
+                 _gr_byname[$1] = $0
+             if ($3 in _gr_bygid)
+                 _gr_bygid[$3] = _gr_bygid[$3] "," $4
+             else
+                 _gr_bygid[$3] = $0
+     
+             n = split($4, a, "[ \t]*,[ \t]*")
+             for (i = 1; i <= n; i++)
+                 if (a[i] in _gr_groupsbyuser)
+                     _gr_groupsbyuser[a[i]] = \
+                         _gr_groupsbyuser[a[i]] " " $1
+                 else
+                     _gr_groupsbyuser[a[i]] = $1
+     
+             _gr_bycount[++_gr_count] = $0
+         }
+         close(grcat)
+         _gr_count = 0
+         _gr_inited++
+         FS = oldfs
+         RS = oldrs
+         $0 = olddol0
+     }
+
+   The `BEGIN' rule sets a private variable to the directory where
+`grcat' is stored.  Since it is used to help out an `awk' library
+routine, we have chosen to put it in `/usr/local/libexec/awk'.  You
+might want it to be in a different directory on your system.
+
+   These routines follow the same general outline as the user database
+routines (*note Reading the User Database: Passwd Functions.).  The
+`_gr_inited' variable is used to ensure that the database is scanned no
+more than once.  The `_gr_init' function first saves `FS', `RS', and
+`$0', and then sets `FS' and `RS' to the correct values for scanning
+the group information.
+
+   The group information is stored is several associative arrays.  The
+arrays are indexed by group name (`_gr_byname'), by group-id number
+(`_gr_bygid'), and by position in the database (`_gr_bycount').  There
+is an additional array indexed by user name (`_gr_groupsbyuser'), that
+is a space separated list of groups that each user belongs to.
+
+   Unlike the user database, it is possible to have multiple records in
+the database for the same group.  This is common when a group has a
+large number of members.  Such a pair of entries might look like:
+
+     tvpeople:*:101:johny,jay,arsenio
+     tvpeople:*:101:david,conan,tom,joan
+
+   For this reason, `_gr_init' looks to see if a group name or group-id
+number has already been seen.  If it has, then the user names are
+simply concatenated onto the previous list of users.  (There is
+actually a subtle problem with the code presented above.  Suppose that
+the first time there were no names. This code adds the names with a
+leading comma. It also doesn't check that there is a `$4'.)
+
+   Finally, `_gr_init' closes the pipeline to `grcat', restores `FS',
+`RS', and `$0', initializes `_gr_count' to zero (it is used later), and
+makes `_gr_inited' non-zero.
+
+     function getgrnam(group)
+     {
+         _gr_init()
+         if (group in _gr_byname)
+             return _gr_byname[group]
+         return ""
+     }
+
+   The `getgrnam' function takes a group name as its argument, and if
+that group exists, it is returned. Otherwise, `getgrnam' returns the
+null string.
+
+     function getgrgid(gid)
+     {
+         _gr_init()
+         if (gid in _gr_bygid)
+             return _gr_bygid[gid]
+         return ""
+     }
+
+   The `getgrgid' function is similar, it takes a numeric group-id, and
+looks up the information associated with that group-id.
+
+     function getgruser(user)
+     {
+         _gr_init()
+         if (user in _gr_groupsbyuser)
+             return _gr_groupsbyuser[user]
+         return ""
+     }
+
+   The `getgruser' function does not have a C counterpart. It takes a
+user name, and returns the list of groups that have the user as a
+member.
+
+     function getgrent()
+     {
+         _gr_init()
+         if (++gr_count in _gr_bycount)
+             return _gr_bycount[_gr_count]
+         return ""
+     }
+
+   The `getgrent' function steps through the database one entry at a
+time.  It uses `_gr_count' to track its position in the list.
+
+     function endgrent()
+     {
+         _gr_count = 0
+     }
+
+   `endgrent' resets `_gr_count' to zero so that `getgrent' can start
+over again.
+
+   As with the user database routines, each function calls `_gr_init' to
+initialize the arrays.  Doing so only incurs the extra overhead of
+running `grcat' if these functions are used (as opposed to moving the
+body of `_gr_init' into a `BEGIN' rule).
+
+   Most of the work is in scanning the database and building the various
+associative arrays.  The functions that the user calls are themselves
+very simple, relying on `awk''s associative arrays to do work.
+
+   The `id' program in *Note Printing Out User Information: Id Program,
+uses these functions.
+
+
+File: gawk.info,  Node: Library Names,  Prev: Group Functions,  Up: Library Functions
+
+Naming Library Function Global Variables
+========================================
+
+   Due to the way the `awk' language evolved, variables are either
+"global" (usable by the entire program), or "local" (usable just by a
+specific function).  There is no intermediate state analogous to
+`static' variables in C.
+
+   Library functions often need to have global variables that they can
+use to preserve state information between calls to the function. For
+example, `getopt''s variable `_opti' (*note Processing Command Line
+Options: Getopt Function.), and the `_tm_months' array used by `mktime'
+(*note Turning Dates Into Timestamps: Mktime Function.).  Such
+variables are called "private", since the only functions that need to
+use them are the ones in the library.
+
+   When writing a library function, you should try to choose names for
+your private variables so that they will not conflict with any
+variables used by either another library function or a user's main
+program.  For example, a name like `i' or `j' is not a good choice,
+since user programs often use variable names like these for their own
+purposes.
+
+   The example programs shown in this chapter all start the names of
+their private variables with an underscore (`_').  Users generally
+don't use leading underscores in their variable names, so this
+convention immediately decreases the chances that the variable name
+will be accidentally shared with the user's program.
+
+   In addition, several of the library functions use a prefix that helps
+indicate what function or set of functions uses the variables. For
+example, `_tm_months' in `mktime' (*note Turning Dates Into Timestamps:
+Mktime Function.), and `_pw_byname' in the user data base routines
+(*note Reading the User Database: Passwd Functions.).  This convention
+is recommended, since it even further decreases the chance of
+inadvertent conflict among variable names.  Note that this convention
+can be used equally well both for variable names and for private
+function names too.
+
+   While I could have re-written all the library routines to use this
+convention, I did not do so, in order to show how my own `awk'
+programming style has evolved, and to provide some basis for this
+discussion.
+
+   As a final note on variable naming, if a function makes global
+variables available for use by a main program, it is a good convention
+to start that variable's name with a capital letter.  For example,
+`getopt''s `Opterr' and `Optind' variables (*note Processing Command
+Line Options: Getopt Function.).  The leading capital letter indicates
+that it is global, while the fact that the variable name is not all
+capital letters indicates that the variable is not one of `awk''s
+built-in variables, like `FS'.
+
+   It is also important that _all_ variables in library functions that
+do not need to save state are in fact declared local.  If this is not
+done, the variable could accidentally be used in the user's program,
+leading to bugs that are very difficult to track down.
+
+     function lib_func(x, y,    l1, l2)
+     {
+         ...
+         USE VARIABLE some_var  # some_var could be local
+         ...                   # but is not by oversight
+     }
+
+   A different convention, common in the Tcl community, is to use a
+single associative array to hold the values needed by the library
+function(s), or "package."  This significantly decreases the number of
+actual global names in use.  For example, the functions described in
+*Note Reading the User Database: Passwd Functions, might have used
+`PW_data["inited"]', `PW_data["total"]', `PW_data["count"]' and
+`PW_data["awklib"]', instead of `_pw_inited', `_pw_awklib', `_pw_total',
+and `_pw_count'.
+
+   The conventions presented in this section are exactly that,
+conventions. You are not required to write your programs this way, we
+merely recommend that you do so.
+
+
+File: gawk.info,  Node: Sample Programs,  Next: Language History,  Prev: Library Functions,  Up: Top
+
+Practical `awk' Programs
+************************
+
+   This chapter presents a potpourri of `awk' programs for your reading
+enjoyment.
+
+   Many of these programs use the library functions presented in *Note
+A Library of `awk' Functions: Library Functions.
+
+* Menu:
+
+* Clones::                    Clones of common utilities.
+* Miscellaneous Programs::    Some interesting `awk' programs.
+
+
+File: gawk.info,  Node: Clones,  Next: Miscellaneous Programs,  Prev: Sample Programs,  Up: Sample Programs
+
+Re-inventing Wheels for Fun and Profit
+======================================
+
+   This section presents a number of POSIX utilities that are
+implemented in `awk'.  Re-inventing these programs in `awk' is often
+enjoyable, since the algorithms can be very clearly expressed, and
+usually the code is very concise and simple.  This is true because
+`awk' does so much for you.
+
+   It should be noted that these programs are not necessarily intended
+to replace the installed versions on your system.  Instead, their
+purpose is to illustrate `awk' language programming for "real world"
+tasks.
+
+   The programs are presented in alphabetical order.
+
+* Menu:
+
+* Cut Program::             The `cut' utility.
+* Egrep Program::           The `egrep' utility.
+* Id Program::              The `id' utility.
+* Split Program::           The `split' utility.
+* Tee Program::             The `tee' utility.
+* Uniq Program::            The `uniq' utility.
+* Wc Program::              The `wc' utility.
+
+
+File: gawk.info,  Node: Cut Program,  Next: Egrep Program,  Prev: Clones,  Up: Clones
+
+Cutting Out Fields and Columns
+------------------------------
+
+   The `cut' utility selects, or "cuts," either characters or fields
+from its standard input and sends them to its standard output.  `cut'
+can cut out either a list of characters, or a list of fields.  By
+default, fields are separated by tabs, but you may supply a command
+line option to change the field "delimiter", i.e. the field separator
+character. `cut''s definition of fields is less general than `awk''s.
+
+   A common use of `cut' might be to pull out just the login name of
+logged-on users from the output of `who'.  For example, the following
+pipeline generates a sorted, unique list of the logged on users:
+
+     who | cut -c1-8 | sort | uniq
+
+   The options for `cut' are:
+
+`-c LIST'
+     Use LIST as the list of characters to cut out.  Items within the
+     list may be separated by commas, and ranges of characters can be
+     separated with dashes.  The list `1-8,15,22-35' specifies
+     characters one through eight, 15, and 22 through 35.
+
+`-f LIST'
+     Use LIST as the list of fields to cut out.
+
+`-d DELIM'
+     Use DELIM as the field separator character instead of the tab
+     character.
+
+`-s'
+     Suppress printing of lines that do not contain the field delimiter.
+
+   The `awk' implementation of `cut' uses the `getopt' library function
+(*note Processing Command Line Options: Getopt Function.), and the
+`join' library function (*note Merging an Array Into a String: Join
+Function.).
+
+   The program begins with a comment describing the options and a
+`usage' function which prints out a usage message and exits.  `usage'
+is called if invalid arguments are supplied.
+
+     # cut.awk --- implement cut in awk
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     # Options:
+     #    -f list        Cut fields
+     #    -d c           Field delimiter character
+     #    -c list        Cut characters
+     #
+     #    -s        Suppress lines without the delimiter character
+     
+     function usage(    e1, e2)
+     {
+         e1 = "usage: cut [-f list] [-d c] [-s] [files...]"
+         e2 = "usage: cut [-c list] [files...]"
+         print e1 > "/dev/stderr"
+         print e2 > "/dev/stderr"
+         exit 1
+     }
+
+The variables `e1' and `e2' are used so that the function fits nicely
+on the screen.
+
+   Next comes a `BEGIN' rule that parses the command line options.  It
+sets `FS' to a single tab character, since that is `cut''s default
+field separator.  The output field separator is also set to be the same
+as the input field separator.  Then `getopt' is used to step through
+the command line options.  One or the other of the variables
+`by_fields' or `by_chars' is set to true, to indicate that processing
+should be done by fields or by characters respectively.  When cutting
+by characters, the output field separator is set to the null string.
+
+     BEGIN    \
+     {
+         FS = "\t"    # default
+         OFS = FS
+         while ((c = getopt(ARGC, ARGV, "sf:c:d:")) != -1) {
+             if (c == "f") {
+                 by_fields = 1
+                 fieldlist = Optarg
+             } else if (c == "c") {
+                 by_chars = 1
+                 fieldlist = Optarg
+                 OFS = ""
+             } else if (c == "d") {
+                 if (length(Optarg) > 1) {
+                     printf("Using first character of %s" \
+                     " for delimiter\n", Optarg) > "/dev/stderr"
+                     Optarg = substr(Optarg, 1, 1)
+                 }
+                 FS = Optarg
+                 OFS = FS
+                 if (FS == " ")    # defeat awk semantics
+                     FS = "[ ]"
+             } else if (c == "s")
+                 suppress++
+             else
+                 usage()
+         }
+     
+         for (i = 1; i < Optind; i++)
+             ARGV[i] = ""
+
+   Special care is taken when the field delimiter is a space. Using
+`" "' (a single space) for the value of `FS' is incorrect--`awk' would
+separate fields with runs of spaces, tabs and/or newlines, and we want
+them to be separated with individual spaces.  Also, note that after
+`getopt' is through, we have to clear out all the elements of `ARGV'
+from one to `Optind', so that `awk' will not try to process the command
+line options as file names.
+
+   After dealing with the command line options, the program verifies
+that the options make sense.  Only one or the other of `-c' and `-f'
+should be used, and both require a field list.  Then either
+`set_fieldlist' or `set_charlist' is called to pull apart the list of
+fields or characters.
+
+         if (by_fields && by_chars)
+             usage()
+     
+         if (by_fields == 0 && by_chars == 0)
+             by_fields = 1    # default
+     
+         if (fieldlist == "") {
+             print "cut: needs list for -c or -f" > "/dev/stderr"
+             exit 1
+         }
+     
+         if (by_fields)
+             set_fieldlist()
+         else
+             set_charlist()
+     }
+
+   Here is `set_fieldlist'.  It first splits the field list apart at
+the commas, into an array.  Then, for each element of the array, it
+looks to see if it is actually a range, and if so splits it apart. The
+range is verified to make sure the first number is smaller than the
+second.  Each number in the list is added to the `flist' array, which
+simply lists the fields that will be printed.  Normal field splitting
+is used.  The program lets `awk' handle the job of doing the field
+splitting.
+
+     function set_fieldlist(        n, m, i, j, k, f, g)
+     {
+         n = split(fieldlist, f, ",")
+         j = 1    # index in flist
+         for (i = 1; i <= n; i++) {
+             if (index(f[i], "-") != 0) { # a range
+                 m = split(f[i], g, "-")
+                 if (m != 2 || g[1] >= g[2]) {
+                     printf("bad field list: %s\n",
+                                       f[i]) > "/dev/stderr"
+                     exit 1
+                 }
+                 for (k = g[1]; k <= g[2]; k++)
+                     flist[j++] = k
+             } else
+                 flist[j++] = f[i]
+         }
+         nfields = j - 1
+     }
+
+   The `set_charlist' function is more complicated than `set_fieldlist'.
+The idea here is to use `gawk''s `FIELDWIDTHS' variable (*note Reading
+Fixed-width Data: Constant Size.), which describes constant width
+input.  When using a character list, that is exactly what we have.
+
+   Setting up `FIELDWIDTHS' is more complicated than simply listing the
+fields that need to be printed.  We have to keep track of the fields to
+be printed, and also the intervening characters that have to be skipped.
+For example, suppose you wanted characters one through eight, 15, and
+22 through 35.  You would use `-c 1-8,15,22-35'.  The necessary value
+for `FIELDWIDTHS' would be `"8 6 1 6 14"'.  This gives us five fields,
+and what should be printed are `$1', `$3', and `$5'.  The intermediate
+fields are "filler," stuff in between the desired data.
+
+   `flist' lists the fields to be printed, and `t' tracks the complete
+field list, including filler fields.
+
+     function set_charlist(    field, i, j, f, g, t,
+                               filler, last, len)
+     {
+         field = 1   # count total fields
+         n = split(fieldlist, f, ",")
+         j = 1       # index in flist
+         for (i = 1; i <= n; i++) {
+             if (index(f[i], "-") != 0) { # range
+                 m = split(f[i], g, "-")
+                 if (m != 2 || g[1] >= g[2]) {
+                     printf("bad character list: %s\n",
+                                    f[i]) > "/dev/stderr"
+                     exit 1
+                 }
+                 len = g[2] - g[1] + 1
+                 if (g[1] > 1)  # compute length of filler
+                     filler = g[1] - last - 1
+                 else
+                     filler = 0
+                 if (filler)
+                     t[field++] = filler
+                 t[field++] = len  # length of field
+                 last = g[2]
+                 flist[j++] = field - 1
+             } else {
+                 if (f[i] > 1)
+                     filler = f[i] - last - 1
+                 else
+                     filler = 0
+                 if (filler)
+                     t[field++] = filler
+                 t[field++] = 1
+                 last = f[i]
+                 flist[j++] = field - 1
+             }
+         }
+         FIELDWIDTHS = join(t, 1, field - 1)
+         nfields = j - 1
+     }
+
+   Here is the rule that actually processes the data.  If the `-s'
+option was given, then `suppress' will be true.  The first `if'
+statement makes sure that the input record does have the field
+separator.  If `cut' is processing fields, `suppress' is true, and the
+field separator character is not in the record, then the record is
+skipped.
+
+   If the record is valid, then at this point, `gawk' has split the data
+into fields, either using the character in `FS' or using fixed-length
+fields and `FIELDWIDTHS'.  The loop goes through the list of fields
+that should be printed.  If the corresponding field has data in it, it
+is printed.  If the next field also has data, then the separator
+character is written out in between the fields.
+
+     {
+         if (by_fields && suppress && $0 !~ FS)
+             next
+     
+         for (i = 1; i <= nfields; i++) {
+             if ($flist[i] != "") {
+                 printf "%s", $flist[i]
+                 if (i < nfields && $flist[i+1] != "")
+                     printf "%s", OFS
+             }
+         }
+         print ""
+     }
+
+   This version of `cut' relies on `gawk''s `FIELDWIDTHS' variable to
+do the character-based cutting.  While it would be possible in other
+`awk' implementations to use `substr' (*note Built-in Functions for
+String Manipulation: String Functions.), it would also be extremely
+painful to do so.  The `FIELDWIDTHS' variable supplies an elegant
+solution to the problem of picking the input line apart by characters.
+
+
+File: gawk.info,  Node: Egrep Program,  Next: Id Program,  Prev: Cut Program,  Up: Clones
+
+Searching for Regular Expressions in Files
+------------------------------------------
+
+   The `egrep' utility searches files for patterns.  It uses regular
+expressions that are almost identical to those available in `awk'
+(*note Regular Expression Constants: Regexp Constants.).  It is used
+this way:
+
+     egrep [ OPTIONS ] 'PATTERN' FILES ...
+
+   The PATTERN is a regexp.  In typical usage, the regexp is quoted to
+prevent the shell from expanding any of the special characters as file
+name wildcards.  Normally, `egrep' prints the lines that matched.  If
+multiple file names are provided on the command line, each output line
+is preceded by the name of the file and a colon.
+
+   The options are:
+
+`-c'
+     Print out a count of the lines that matched the pattern, instead
+     of the lines themselves.
+
+`-s'
+     Be silent.  No output is produced, and the exit value indicates
+     whether or not the pattern was matched.
+
+`-v'
+     Invert the sense of the test. `egrep' prints the lines that do
+     _not_ match the pattern, and exits successfully if the pattern was
+     not matched.
+
+`-i'
+     Ignore case distinctions in both the pattern and the input data.
+
+`-l'
+     Only print the names of the files that matched, not the lines that
+     matched.
+
+`-e PATTERN'
+     Use PATTERN as the regexp to match.  The purpose of the `-e'
+     option is to allow patterns that start with a `-'.
+
+   This version uses the `getopt' library function (*note Processing
+Command Line Options: Getopt Function.), and the file transition
+library program (*note Noting Data File Boundaries: Filetrans
+Function.).
+
+   The program begins with a descriptive comment, and then a `BEGIN'
+rule that processes the command line arguments with `getopt'.  The `-i'
+(ignore case) option is particularly easy with `gawk'; we just use the
+`IGNORECASE' built in variable (*note Built-in Variables::).
+
+     # egrep.awk --- simulate egrep in awk
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     # Options:
+     #    -c    count of lines
+     #    -s    silent - use exit value
+     #    -v    invert test, success if no match
+     #    -i    ignore case
+     #    -l    print filenames only
+     #    -e    argument is pattern
+     
+     BEGIN {
+         while ((c = getopt(ARGC, ARGV, "ce:svil")) != -1) {
+             if (c == "c")
+                 count_only++
+             else if (c == "s")
+                 no_print++
+             else if (c == "v")
+                 invert++
+             else if (c == "i")
+                 IGNORECASE = 1
+             else if (c == "l")
+                 filenames_only++
+             else if (c == "e")
+                 pattern = Optarg
+             else
+                 usage()
+         }
+
+   Next comes the code that handles the `egrep' specific behavior. If no
+pattern was supplied with `-e', the first non-option on the command
+line is used.  The `awk' command line arguments up to `ARGV[Optind]'
+are cleared, so that `awk' won't try to process them as files.  If no
+files were specified, the standard input is used, and if multiple files
+were specified, we make sure to note this so that the file names can
+precede the matched lines in the output.
+
+   The last two lines are commented out, since they are not needed in
+`gawk'.  They should be uncommented if you have to use another version
+of `awk'.
+
+         if (pattern == "")
+             pattern = ARGV[Optind++]
+     
+         for (i = 1; i < Optind; i++)
+             ARGV[i] = ""
+         if (Optind >= ARGC) {
+             ARGV[1] = "-"
+             ARGC = 2
+         } else if (ARGC - Optind > 1)
+             do_filenames++
+     
+     #    if (IGNORECASE)
+     #        pattern = tolower(pattern)
+     }
+
+   The next set of lines should be uncommented if you are not using
+`gawk'.  This rule translates all the characters in the input line into
+lower-case if the `-i' option was specified.  The rule is commented out
+since it is not necessary with `gawk'.
+
+     #{
+     #    if (IGNORECASE)
+     #        $0 = tolower($0)
+     #}
+
+   The `beginfile' function is called by the rule in `ftrans.awk' when
+each new file is processed.  In this case, it is very simple; all it
+does is initialize a variable `fcount' to zero. `fcount' tracks how
+many lines in the current file matched the pattern.
+
+     function beginfile(junk)
+     {
+         fcount = 0
+     }
+
+   The `endfile' function is called after each file has been processed.
+It is used only when the user wants a count of the number of lines that
+matched.  `no_print' will be true only if the exit status is desired.
+`count_only' will be true if line counts are desired.  `egrep' will
+therefore only print line counts if printing and counting are enabled.
+The output format must be adjusted depending upon the number of files
+to be processed.  Finally, `fcount' is added to `total', so that we
+know how many lines altogether matched the pattern.
+
+     function endfile(file)
+     {
+         if (! no_print && count_only)
+             if (do_filenames)
+                 print file ":" fcount
+             else
+                 print fcount
+     
+         total += fcount
+     }
+
+   This rule does most of the work of matching lines. The variable
+`matches' will be true if the line matched the pattern. If the user
+wants lines that did not match, the sense of the `matches' is inverted
+using the `!' operator. `fcount' is incremented with the value of
+`matches', which will be either one or zero, depending upon a
+successful or unsuccessful match.  If the line did not match, the
+`next' statement just moves on to the next record.
+
+   There are several optimizations for performance in the following few
+lines of code. If the user only wants exit status (`no_print' is true),
+and we don't have to count lines, then it is enough to know that one
+line in this file matched, and we can skip on to the next file with
+`nextfile'.  Along similar lines, if we are only printing file names,
+and we don't need to count lines, we can print the file name, and then
+skip to the next file with `nextfile'.
+
+   Finally, each line is printed, with a leading filename and colon if
+necessary.
+
+     {
+         matches = ($0 ~ pattern)
+         if (invert)
+             matches = ! matches
+     
+         fcount += matches    # 1 or 0
+     
+         if (! matches)
+             next
+     
+         if (no_print && ! count_only)
+             nextfile
+     
+         if (filenames_only && ! count_only) {
+             print FILENAME
+             nextfile
+         }
+     
+         if (do_filenames && ! count_only)
+             print FILENAME ":" $0
+         else if (! count_only)
+             print
+     }
+
+   The `END' rule takes care of producing the correct exit status. If
+there were no matches, the exit status is one, otherwise it is zero.
+
+     END    \
+     {
+         if (total == 0)
+             exit 1
+         exit 0
+     }
+
+   The `usage' function prints a usage message in case of invalid
+options and then exits.
+
+     function usage(    e)
+     {
+         e = "Usage: egrep [-csvil] [-e pat] [files ...]"
+         print e > "/dev/stderr"
+         exit 1
+     }
+
+   The variable `e' is used so that the function fits nicely on the
+printed page.
+
+   Just a note on programming style. You may have noticed that the `END'
+rule uses backslash continuation, with the open brace on a line by
+itself.  This is so that it more closely resembles the way functions
+are written.  Many of the examples use this style. You can decide for
+yourself if you like writing your `BEGIN' and `END' rules this way, or
+not.
+
+
+File: gawk.info,  Node: Id Program,  Next: Split Program,  Prev: Egrep Program,  Up: Clones
+
+Printing Out User Information
+-----------------------------
+
+   The `id' utility lists a user's real and effective user-id numbers,
+real and effective group-id numbers, and the user's group set, if any.
+`id' will only print the effective user-id and group-id if they are
+different from the real ones.  If possible, `id' will also supply the
+corresponding user and group names.  The output might look like this:
+
+     $ id
+     -| uid=2076(arnold) gid=10(staff) groups=10(staff),4(tty)
+
+   This information is exactly what is provided by `gawk''s `/dev/user'
+special file (*note Special File Names in `gawk': Special Files.).
+However, the `id' utility provides a more palatable output than just a
+string of numbers.
+
+   Here is a simple version of `id' written in `awk'.  It uses the user
+database library functions (*note Reading the User Database: Passwd
+Functions.), and the group database library functions (*note Reading
+the Group Database: Group Functions.).
+
+   The program is fairly straightforward.  All the work is done in the
+`BEGIN' rule.  The user and group id numbers are obtained from
+`/dev/user'.  If there is no support for `/dev/user', the program gives
+up.
+
+   The code is repetitive.  The entry in the user database for the real
+user-id number is split into parts at the `:'. The name is the first
+field.  Similar code is used for the effective user-id number, and the
+group numbers.
+
+     # id.awk --- implement id in awk
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     # output is:
+     # uid=12(foo) euid=34(bar) gid=3(baz) \
+     #             egid=5(blat) groups=9(nine),2(two),1(one)
+     
+     BEGIN    \
+     {
+         if ((getline < "/dev/user") < 0) {
+             err = "id: no /dev/user support - cannot run"
+             print err > "/dev/stderr"
+             exit 1
+         }
+         close("/dev/user")
+     
+         uid = $1
+         euid = $2
+         gid = $3
+         egid = $4
+     
+         printf("uid=%d", uid)
+         pw = getpwuid(uid)
+         if (pw != "") {
+             split(pw, a, ":")
+             printf("(%s)", a[1])
+         }
+     
+         if (euid != uid) {
+             printf(" euid=%d", euid)
+             pw = getpwuid(euid)
+             if (pw != "") {
+                 split(pw, a, ":")
+                 printf("(%s)", a[1])
+             }
+         }
+     
+         printf(" gid=%d", gid)
+         pw = getgrgid(gid)
+         if (pw != "") {
+             split(pw, a, ":")
+             printf("(%s)", a[1])
+         }
+     
+         if (egid != gid) {
+             printf(" egid=%d", egid)
+             pw = getgrgid(egid)
+             if (pw != "") {
+                 split(pw, a, ":")
+                 printf("(%s)", a[1])
+             }
+         }
+     
+         if (NF > 4) {
+             printf(" groups=");
+             for (i = 5; i <= NF; i++) {
+                 printf("%d", $i)
+                 pw = getgrgid($i)
+                 if (pw != "") {
+                     split(pw, a, ":")
+                     printf("(%s)", a[1])
+                 }
+                 if (i < NF)
+                     printf(",")
+             }
+         }
+         print ""
+     }
+
+
+File: gawk.info,  Node: Split Program,  Next: Tee Program,  Prev: Id Program,  Up: Clones
+
+Splitting a Large File Into Pieces
+----------------------------------
+
+   The `split' program splits large text files into smaller pieces. By
+default, the output files are named `xaa', `xab', and so on. Each file
+has 1000 lines in it, with the likely exception of the last file. To
+change the number of lines in each file, you supply a number on the
+command line preceded with a minus, e.g., `-500' for files with 500
+lines in them instead of 1000.  To change the name of the output files
+to something like `myfileaa', `myfileab', and so on, you supply an
+additional argument that specifies the filename.
+
+   Here is a version of `split' in `awk'. It uses the `ord' and `chr'
+functions presented in *Note Translating Between Characters and
+Numbers: Ordinal Functions.
+
+   The program first sets its defaults, and then tests to make sure
+there are not too many arguments.  It then looks at each argument in
+turn.  The first argument could be a minus followed by a number. If it
+is, this happens to look like a negative number, so it is made
+positive, and that is the count of lines.  The data file name is
+skipped over, and the final argument is used as the prefix for the
+output file names.
+
+     # split.awk --- do split in awk
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     # usage: split [-num] [file] [outname]
+     
+     BEGIN    \
+     {
+         outfile = "x"    # default
+         count = 1000
+         if (ARGC > 4)
+             usage()
+     
+         i = 1
+         if (ARGV[i] ~ /^-[0-9]+$/) {
+             count = -ARGV[i]
+             ARGV[i] = ""
+             i++
+         }
+         # test argv in case reading from stdin instead of file
+         if (i in ARGV)
+             i++    # skip data file name
+         if (i in ARGV) {
+             outfile = ARGV[i]
+             ARGV[i] = ""
+         }
+     
+         s1 = s2 = "a"
+         out = (outfile s1 s2)
+     }
+
+   The next rule does most of the work. `tcount' (temporary count)
+tracks how many lines have been printed to the output file so far. If
+it is greater than `count', it is time to close the current file and
+start a new one.  `s1' and `s2' track the current suffixes for the file
+name. If they are both `z', the file is just too big.  Otherwise, `s1'
+moves to the next letter in the alphabet and `s2' starts over again at
+`a'.
+
+     {
+         if (++tcount > count) {
+             close(out)
+             if (s2 == "z") {
+                 if (s1 == "z") {
+                     printf("split: %s is too large to split\n", \
+                            FILENAME) > "/dev/stderr"
+                     exit 1
+                 }
+                 s1 = chr(ord(s1) + 1)
+                 s2 = "a"
+             } else
+                 s2 = chr(ord(s2) + 1)
+             out = (outfile s1 s2)
+             tcount = 1
+         }
+         print > out
+     }
+
+   The `usage' function simply prints an error message and exits.
+
+     function usage(   e)
+     {
+         e = "usage: split [-num] [file] [outname]"
+         print e > "/dev/stderr"
+         exit 1
+     }
+
+The variable `e' is used so that the function fits nicely on the screen.
+
+   This program is a bit sloppy; it relies on `awk' to close the last
+file for it automatically, instead of doing it in an `END' rule.
+
+
+File: gawk.info,  Node: Tee Program,  Next: Uniq Program,  Prev: Split Program,  Up: Clones
+
+Duplicating Output Into Multiple Files
+--------------------------------------
+
+   The `tee' program is known as a "pipe fitting."  `tee' copies its
+standard input to its standard output, and also duplicates it to the
+files named on the command line.  Its usage is:
+
+     tee [-a] file ...
+
+   The `-a' option tells `tee' to append to the named files, instead of
+truncating them and starting over.
+
+   The `BEGIN' rule first makes a copy of all the command line
+arguments, into an array named `copy'.  `ARGV[0]' is not copied, since
+it is not needed.  `tee' cannot use `ARGV' directly, since `awk' will
+attempt to process each file named in `ARGV' as input data.
+
+   If the first argument is `-a', then the flag variable `append' is
+set to true, and both `ARGV[1]' and `copy[1]' are deleted. If `ARGC' is
+less than two, then no file names were supplied, and `tee' prints a
+usage message and exits.  Finally, `awk' is forced to read the standard
+input by setting `ARGV[1]' to `"-"', and `ARGC' to two.
+
+     # tee.awk --- tee in awk
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     # Revised December 1995
+     
+     BEGIN    \
+     {
+         for (i = 1; i < ARGC; i++)
+             copy[i] = ARGV[i]
+     
+         if (ARGV[1] == "-a") {
+             append = 1
+             delete ARGV[1]
+             delete copy[1]
+             ARGC--
+         }
+         if (ARGC < 2) {
+             print "usage: tee [-a] file ..." > "/dev/stderr"
+             exit 1
+         }
+         ARGV[1] = "-"
+         ARGC = 2
+     }
+
+   The single rule does all the work.  Since there is no pattern, it is
+executed for each line of input.  The body of the rule simply prints the
+line into each file on the command line, and then to the standard
+output.
+
+     {
+         # moving the if outside the loop makes it run faster
+         if (append)
+             for (i in copy)
+                 print >> copy[i]
+         else
+             for (i in copy)
+                 print > copy[i]
+         print
+     }
+
+   It would have been possible to code the loop this way:
+
+     for (i in copy)
+         if (append)
+             print >> copy[i]
+         else
+             print > copy[i]
+
+This is more concise, but it is also less efficient.  The `if' is
+tested for each record and for each output file.  By duplicating the
+loop body, the `if' is only tested once for each input record.  If
+there are N input records and M input files, the first method only
+executes N `if' statements, while the second would execute N`*'M `if'
+statements.
+
+   Finally, the `END' rule cleans up, by closing all the output files.
+
+     END    \
+     {
+         for (i in copy)
+             close(copy[i])
+     }
+
+
+File: gawk.info,  Node: Uniq Program,  Next: Wc Program,  Prev: Tee Program,  Up: Clones
+
+Printing Non-duplicated Lines of Text
+-------------------------------------
+
+   The `uniq' utility reads sorted lines of data on its standard input,
+and (by default) removes duplicate lines.  In other words, only unique
+lines are printed, hence the name.  `uniq' has a number of options. The
+usage is:
+
+     uniq [-udc [-N]] [+N] [ INPUT FILE [ OUTPUT FILE ]]
+
+   The option meanings are:
+
+`-d'
+     Only print repeated lines.
+
+`-u'
+     Only print non-repeated lines.
+
+`-c'
+     Count lines. This option overrides `-d' and `-u'.  Both repeated
+     and non-repeated lines are counted.
+
+`-N'
+     Skip N fields before comparing lines.  The definition of fields is
+     similar to `awk''s default: non-whitespace characters separated by
+     runs of spaces and/or tabs.
+
+`+N'
+     Skip N characters before comparing lines.  Any fields specified
+     with `-N' are skipped first.
+
+`INPUT FILE'
+     Data is read from the input file named on the command line,
+     instead of from the standard input.
+
+`OUTPUT FILE'
+     The generated output is sent to the named output file, instead of
+     to the standard output.
+
+   Normally `uniq' behaves as if both the `-d' and `-u' options had
+been provided.
+
+   Here is an `awk' implementation of `uniq'. It uses the `getopt'
+library function (*note Processing Command Line Options: Getopt
+Function.), and the `join' library function (*note Merging an Array
+Into a String: Join Function.).
+
+   The program begins with a `usage' function and then a brief outline
+of the options and their meanings in a comment.
+
+   The `BEGIN' rule deals with the command line arguments and options.
+It uses a trick to get `getopt' to handle options of the form `-25',
+treating such an option as the option letter `2' with an argument of
+`5'. If indeed two or more digits were supplied (`Optarg' looks like a
+number), `Optarg' is concatenated with the option digit, and then
+result is added to zero to make it into a number.  If there is only one
+digit in the option, then `Optarg' is not needed, and `Optind' must be
+decremented so that `getopt' will process it next time.  This code is
+admittedly a bit tricky.
+
+   If no options were supplied, then the default is taken, to print both
+repeated and non-repeated lines.  The output file, if provided, is
+assigned to `outputfile'.  Earlier, `outputfile' was initialized to the
+standard output, `/dev/stdout'.
+
+     # uniq.awk --- do uniq in awk
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     function usage(    e)
+     {
+         e = "Usage: uniq [-udc [-n]] [+n] [ in [ out ]]"
+         print e > "/dev/stderr"
+         exit 1
+     }
+     
+     # -c    count lines. overrides -d and -u
+     # -d    only repeated lines
+     # -u    only non-repeated lines
+     # -n    skip n fields
+     # +n    skip n characters, skip fields first
+     
+     BEGIN    \
+     {
+         count = 1
+         outputfile = "/dev/stdout"
+         opts = "udc0:1:2:3:4:5:6:7:8:9:"
+         while ((c = getopt(ARGC, ARGV, opts)) != -1) {
+             if (c == "u")
+                 non_repeated_only++
+             else if (c == "d")
+                 repeated_only++
+             else if (c == "c")
+                 do_count++
+             else if (index("0123456789", c) != 0) {
+                 # getopt requires args to options
+                 # this messes us up for things like -5
+                 if (Optarg ~ /^[0-9]+$/)
+                     fcount = (c Optarg) + 0
+                 else {
+                     fcount = c + 0
+                     Optind--
+                 }
+             } else
+                 usage()
+         }
+     
+         if (ARGV[Optind] ~ /^\+[0-9]+$/) {
+             charcount = substr(ARGV[Optind], 2) + 0
+             Optind++
+         }
+     
+         for (i = 1; i < Optind; i++)
+             ARGV[i] = ""
+     
+         if (repeated_only == 0 && non_repeated_only == 0)
+             repeated_only = non_repeated_only = 1
+     
+         if (ARGC - Optind == 2) {
+             outputfile = ARGV[ARGC - 1]
+             ARGV[ARGC - 1] = ""
+         }
+     }
+
+   The following function, `are_equal', compares the current line,
+`$0', to the previous line, `last'.  It handles skipping fields and
+characters.
+
+   If no field count and no character count were specified, `are_equal'
+simply returns one or zero depending upon the result of a simple string
+comparison of `last' and `$0'.  Otherwise, things get more complicated.
+
+   If fields have to be skipped, each line is broken into an array using
+`split' (*note Built-in Functions for String Manipulation: String
+Functions.), and then the desired fields are joined back into a line
+using `join'.  The joined lines are stored in `clast' and `cline'.  If
+no fields are skipped, `clast' and `cline' are set to `last' and `$0'
+respectively.
+
+   Finally, if characters are skipped, `substr' is used to strip off the
+leading `charcount' characters in `clast' and `cline'.  The two strings
+are then compared, and `are_equal' returns the result.
+
+     function are_equal(    n, m, clast, cline, alast, aline)
+     {
+         if (fcount == 0 && charcount == 0)
+             return (last == $0)
+     
+         if (fcount > 0) {
+             n = split(last, alast)
+             m = split($0, aline)
+             clast = join(alast, fcount+1, n)
+             cline = join(aline, fcount+1, m)
+         } else {
+             clast = last
+             cline = $0
+         }
+         if (charcount) {
+             clast = substr(clast, charcount + 1)
+             cline = substr(cline, charcount + 1)
+         }
+     
+         return (clast == cline)
+     }
+
+   The following two rules are the body of the program.  The first one
+is executed only for the very first line of data.  It sets `last' equal
+to `$0', so that subsequent lines of text have something to be compared
+to.
+
+   The second rule does the work. The variable `equal' will be one or
+zero depending upon the results of `are_equal''s comparison. If `uniq'
+is counting repeated lines, then the `count' variable is incremented if
+the lines are equal. Otherwise the line is printed and `count' is
+reset, since the two lines are not equal.
+
+   If `uniq' is not counting, `count' is incremented if the lines are
+equal. Otherwise, if `uniq' is counting repeated lines, and more than
+one line has been seen, or if `uniq' is counting non-repeated lines,
+and only one line has been seen, then the line is printed, and `count'
+is reset.
+
+   Finally, similar logic is used in the `END' rule to print the final
+line of input data.
+
+     NR == 1 {
+         last = $0
+         next
+     }
+     
+     {
+         equal = are_equal()
+     
+         if (do_count) {    # overrides -d and -u
+             if (equal)
+                 count++
+             else {
+                 printf("%4d %s\n", count, last) > outputfile
+                 last = $0
+                 count = 1    # reset
+             }
+             next
+         }
+     
+         if (equal)
+             count++
+         else {
+             if ((repeated_only && count > 1) ||
+                 (non_repeated_only && count == 1))
+                     print last > outputfile
+             last = $0
+             count = 1
+         }
+     }
+     
+     END {
+         if (do_count)
+             printf("%4d %s\n", count, last) > outputfile
+         else if ((repeated_only && count > 1) ||
+                 (non_repeated_only && count == 1))
+             print last > outputfile
+     }
+
+
+File: gawk.info,  Node: Wc Program,  Prev: Uniq Program,  Up: Clones
+
+Counting Things
+---------------
+
+   The `wc' (word count) utility counts lines, words, and characters in
+one or more input files. Its usage is:
+
+     wc [-lwc] [ FILES ... ]
+
+   If no files are specified on the command line, `wc' reads its
+standard input. If there are multiple files, it will also print total
+counts for all the files.  The options and their meanings are:
+
+`-l'
+     Only count lines.
+
+`-w'
+     Only count words.  A "word" is a contiguous sequence of
+     non-whitespace characters, separated by spaces and/or tabs.
+     Happily, this is the normal way `awk' separates fields in its
+     input data.
+
+`-c'
+     Only count characters.
+
+   Implementing `wc' in `awk' is particularly elegant, since `awk' does
+a lot of the work for us; it splits lines into words (i.e.  fields) and
+counts them, it counts lines (i.e. records) for us, and it can easily
+tell us how long a line is.
+
+   This version uses the `getopt' library function (*note Processing
+Command Line Options: Getopt Function.), and the file transition
+functions (*note Noting Data File Boundaries: Filetrans Function.).
+
+   This version has one major difference from traditional versions of
+`wc'.  Our version always prints the counts in the order lines, words,
+and characters.  Traditional versions note the order of the `-l', `-w',
+and `-c' options on the command line, and print the counts in that
+order.
+
+   The `BEGIN' rule does the argument processing.  The variable
+`print_total' will be true if more than one file was named on the
+command line.
+
+     # wc.awk --- count lines, words, characters
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     # Options:
+     #    -l    only count lines
+     #    -w    only count words
+     #    -c    only count characters
+     #
+     # Default is to count lines, words, characters
+     
+     BEGIN {
+         # let getopt print a message about
+         # invalid options. we ignore them
+         while ((c = getopt(ARGC, ARGV, "lwc")) != -1) {
+             if (c == "l")
+                 do_lines = 1
+             else if (c == "w")
+                 do_words = 1
+             else if (c == "c")
+                 do_chars = 1
+         }
+         for (i = 1; i < Optind; i++)
+             ARGV[i] = ""
+     
+         # if no options, do all
+         if (! do_lines && ! do_words && ! do_chars)
+             do_lines = do_words = do_chars = 1
+     
+         print_total = (ARGC - i > 2)
+     }
+
+   The `beginfile' function is simple; it just resets the counts of
+lines, words, and characters to zero, and saves the current file name in
+`fname'.
+
+   The `endfile' function adds the current file's numbers to the running
+totals of lines, words, and characters.  It then prints out those
+numbers for the file that was just read. It relies on `beginfile' to
+reset the numbers for the following data file.
+
+     function beginfile(file)
+     {
+         chars = lines = words = 0
+         fname = FILENAME
+     }
+     
+     function endfile(file)
+     {
+         tchars += chars
+         tlines += lines
+         twords += words
+         if (do_lines)
+             printf "\t%d", lines
+         if (do_words)
+             printf "\t%d", words
+         if (do_chars)
+             printf "\t%d", chars
+         printf "\t%s\n", fname
+     }
+
+   There is one rule that is executed for each line. It adds the length
+of the record to `chars'.  It has to add one, since the newline
+character separating records (the value of `RS') is not part of the
+record itself.  `lines' is incremented for each line read, and `words'
+is incremented by the value of `NF', the number of "words" on this
+line.(1)
+
+   Finally, the `END' rule simply prints the totals for all the files.
+
+     # do per line
+     {
+         chars += length($0) + 1    # get newline
+         lines++
+         words += NF
+     }
+     
+     END {
+         if (print_total) {
+             if (do_lines)
+                 printf "\t%d", tlines
+             if (do_words)
+                 printf "\t%d", twords
+             if (do_chars)
+                 printf "\t%d", tchars
+             print "\ttotal"
+         }
+     }
+
+   ---------- Footnotes ----------
+
+   (1) Examine the code in *Note Noting Data File Boundaries: Filetrans
+Function.  Why must `wc' use a separate `lines' variable, instead of
+using the value of `FNR' in `endfile'?
+
+
+File: gawk.info,  Node: Miscellaneous Programs,  Prev: Clones,  Up: Sample Programs
+
+A Grab Bag of `awk' Programs
+============================
+
+   This section is a large "grab bag" of miscellaneous programs.  We
+hope you find them both interesting and enjoyable.
+
+* Menu:
+
+* Dupword Program::         Finding duplicated words in a document.
+* Alarm Program::           An alarm clock.
+* Translate Program::       A program similar to the `tr' utility.
+* Labels Program::          Printing mailing labels.
+* Word Sorting::            A program to produce a word usage count.
+* History Sorting::         Eliminating duplicate entries from a history
+                            file.
+* Extract Program::         Pulling out programs from Texinfo source
+                            files.
+* Simple Sed::              A Simple Stream Editor.
+* Igawk Program::           A wrapper for `awk' that includes files.
+
+
+File: gawk.info,  Node: Dupword Program,  Next: Alarm Program,  Prev: Miscellaneous Programs,  Up: Miscellaneous Programs
+
+Finding Duplicated Words in a Document
+--------------------------------------
+
+   A common error when writing large amounts of prose is to accidentally
+duplicate words.  Often you will see this in text as something like "the
+the program does the following ...."  When the text is on-line, often
+the duplicated words occur at the end of one line and the beginning of
+another, making them very difficult to spot.
+
+   This program, `dupword.awk', scans through a file one line at a time,
+and looks for adjacent occurrences of the same word.  It also saves the
+last word on a line (in the variable `prev') for comparison with the
+first word on the next line.
+
+   The first two statements make sure that the line is all lower-case,
+so that, for example, "The" and "the" compare equal to each other.  The
+second statement removes all non-alphanumeric and non-whitespace
+characters from the line, so that punctuation does not affect the
+comparison either.  This sometimes leads to reports of duplicated words
+that really are different, but this is unusual.
+
+     # dupword --- find duplicate words in text
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # December 1991
+     
+     {
+         $0 = tolower($0)
+         gsub(/[^A-Za-z0-9 \t]/, "");
+         if ($1 == prev)
+             printf("%s:%d: duplicate %s\n",
+                 FILENAME, FNR, $1)
+         for (i = 2; i <= NF; i++)
+             if ($i == $(i-1))
+                 printf("%s:%d: duplicate %s\n",
+                     FILENAME, FNR, $i)
+         prev = $NF
+     }
+
+
+File: gawk.info,  Node: Alarm Program,  Next: Translate Program,  Prev: Dupword Program,  Up: Miscellaneous Programs
+
+An Alarm Clock Program
+----------------------
+
+   The following program is a simple "alarm clock" program.  You give
+it a time of day, and an optional message.  At the given time, it
+prints the message on the standard output. In addition, you can give it
+the number of times to repeat the message, and also a delay between
+repetitions.
+
+   This program uses the `gettimeofday' function from *Note Managing
+the Time of Day: Gettimeofday Function.
+
+   All the work is done in the `BEGIN' rule.  The first part is argument
+checking and setting of defaults; the delay, the count, and the message
+to print.  If the user supplied a message, but it does not contain the
+ASCII BEL character (known as the "alert" character, `\a'), then it is
+added to the message.  (On many systems, printing the ASCII BEL
+generates some sort of audible alert. Thus, when the alarm goes off,
+the system calls attention to itself, in case the user is not looking
+at their computer or terminal.)
+
+     # alarm --- set an alarm
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     # usage: alarm time [ "message" [ count [ delay ] ] ]
+     
+     BEGIN    \
+     {
+         # Initial argument sanity checking
+         usage1 = "usage: alarm time ['message' [count [delay]]]"
+         usage2 = sprintf("\t(%s) time ::= hh:mm", ARGV[1])
+     
+         if (ARGC < 2) {
+             print usage > "/dev/stderr"
+             exit 1
+         } else if (ARGC == 5) {
+             delay = ARGV[4] + 0
+             count = ARGV[3] + 0
+             message = ARGV[2]
+         } else if (ARGC == 4) {
+             count = ARGV[3] + 0
+             message = ARGV[2]
+         } else if (ARGC == 3) {
+             message = ARGV[2]
+         } else if (ARGV[1] !~ /[0-9]?[0-9]:[0-9][0-9]/) {
+             print usage1 > "/dev/stderr"
+             print usage2 > "/dev/stderr"
+             exit 1
+         }
+     
+         # set defaults for once we reach the desired time
+         if (delay == 0)
+             delay = 180    # 3 minutes
+         if (count == 0)
+             count = 5
+         if (message == "")
+             message = sprintf("\aIt is now %s!\a", ARGV[1])
+         else if (index(message, "\a") == 0)
+             message = "\a" message "\a"
+
+   The next section of code turns the alarm time into hours and minutes,
+and converts it if necessary to a 24-hour clock.  Then it turns that
+time into a count of the seconds since midnight.  Next it turns the
+current time into a count of seconds since midnight.  The difference
+between the two is how long to wait before setting off the alarm.
+
+         # split up dest time
+         split(ARGV[1], atime, ":")
+         hour = atime[1] + 0    # force numeric
+         minute = atime[2] + 0  # force numeric
+     
+         # get current broken down time
+         gettimeofday(now)
+     
+         # if time given is 12-hour hours and it's after that
+         # hour, e.g., `alarm 5:30' at 9 a.m. means 5:30 p.m.,
+         # then add 12 to real hour
+         if (hour < 12 && now["hour"] > hour)
+             hour += 12
+     
+         # set target time in seconds since midnight
+         target = (hour * 60 * 60) + (minute * 60)
+     
+         # get current time in seconds since midnight
+         current = (now["hour"] * 60 * 60) + \
+                    (now["minute"] * 60) + now["second"]
+     
+         # how long to sleep for
+         naptime = target - current
+         if (naptime <= 0) {
+             print "time is in the past!" > "/dev/stderr"
+             exit 1
+         }
+
+   Finally, the program uses the `system' function (*note Built-in
+Functions for Input/Output: I/O Functions.)  to call the `sleep'
+utility.  The `sleep' utility simply pauses for the given number of
+seconds.  If the exit status is not zero, the program assumes that
+`sleep' was interrupted, and exits. If `sleep' exited with an OK status
+(zero), then the program prints the message in a loop, again using
+`sleep' to delay for however many seconds are necessary.
+
+         # zzzzzz..... go away if interrupted
+         if (system(sprintf("sleep %d", naptime)) != 0)
+             exit 1
+     
+         # time to notify!
+         command = sprintf("sleep %d", delay)
+         for (i = 1; i <= count; i++) {
+             print message
+             # if sleep command interrupted, go away
+             if (system(command) != 0)
+                 break
+         }
+     
+         exit 0
+     }
+
+
+File: gawk.info,  Node: Translate Program,  Next: Labels Program,  Prev: Alarm Program,  Up: Miscellaneous Programs
+
+Transliterating Characters
+--------------------------
+
+   The system `tr' utility transliterates characters.  For example, it
+is often used to map upper-case letters into lower-case, for further
+processing.
+
+     GENERATE DATA | tr '[A-Z]' '[a-z]' | PROCESS DATA ...
+
+   You give `tr' two lists of characters enclosed in square brackets.
+Usually, the lists are quoted to keep the shell from attempting to do a
+filename expansion.(1)  When processing the input, the first character
+in the first list is replaced with the first character in the second
+list, the second character in the first list is replaced with the
+second character in the second list, and so on.  If there are more
+characters in the "from" list than in the "to" list, the last character
+of the "to" list is used for the remaining characters in the "from"
+list.
+
+   Some time ago, a user proposed to us that we add a transliteration
+function to `gawk'.  Being opposed to "creeping featurism," I wrote the
+following program to prove that character transliteration could be done
+with a user-level function.  This program is not as complete as the
+system `tr' utility, but it will do most of the job.
+
+   The `translate' program demonstrates one of the few weaknesses of
+standard `awk': dealing with individual characters is very painful,
+requiring repeated use of the `substr', `index', and `gsub' built-in
+functions (*note Built-in Functions for String Manipulation: String
+Functions.).(2)
+
+   There are two functions.  The first, `stranslate', takes three
+arguments.
+
+`from'
+     A list of characters to translate from.
+
+`to'
+     A list of characters to translate to.
+
+`target'
+     The string to do the translation on.
+
+   Associative arrays make the translation part fairly easy. `t_ar'
+holds the "to" characters, indexed by the "from" characters.  Then a
+simple loop goes through `from', one character at a time.  For each
+character in `from', if the character appears in `target', `gsub' is
+used to change it to the corresponding `to' character.
+
+   The `translate' function simply calls `stranslate' using `$0' as the
+target.  The main program sets two global variables, `FROM' and `TO',
+from the command line, and then changes `ARGV' so that `awk' will read
+from the standard input.
+
+   Finally, the processing rule simply calls `translate' for each
+record.
+
+     # translate --- do tr like stuff
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # August 1989
+     
+     # bugs: does not handle things like: tr A-Z a-z, it has
+     # to be spelled out. However, if `to' is shorter than `from',
+     # the last character in `to' is used for the rest of `from'.
+     
+     function stranslate(from, to, target,     lf, lt, t_ar, i, c)
+     {
+         lf = length(from)
+         lt = length(to)
+         for (i = 1; i <= lt; i++)
+             t_ar[substr(from, i, 1)] = substr(to, i, 1)
+         if (lt < lf)
+             for (; i <= lf; i++)
+                 t_ar[substr(from, i, 1)] = substr(to, lt, 1)
+         for (i = 1; i <= lf; i++) {
+             c = substr(from, i, 1)
+             if (index(target, c) > 0)
+                 gsub(c, t_ar[c], target)
+         }
+         return target
+     }
+     
+     function translate(from, to)
+     {
+         return $0 = stranslate(from, to, $0)
+     }
+     
+     # main program
+     BEGIN {
+         if (ARGC < 3) {
+             print "usage: translate from to" > "/dev/stderr"
+             exit
+         }
+         FROM = ARGV[1]
+         TO = ARGV[2]
+         ARGC = 2
+         ARGV[1] = "-"
+     }
+     
+     {
+         translate(FROM, TO)
+         print
+     }
+
+   While it is possible to do character transliteration in a user-level
+function, it is not necessarily efficient, and we started to consider
+adding a built-in function.  However, shortly after writing this
+program, we learned that the System V Release 4 `awk' had added the
+`toupper' and `tolower' functions.  These functions handle the vast
+majority of the cases where character transliteration is necessary, and
+so we chose to simply add those functions to `gawk' as well, and then
+leave well enough alone.
+
+   An obvious improvement to this program would be to set up the `t_ar'
+array only once, in a `BEGIN' rule. However, this assumes that the
+"from" and "to" lists will never change throughout the lifetime of the
+program.
+
+   ---------- Footnotes ----------
+
+   (1) On older, non-POSIX systems, `tr' often does not require that
+the lists be enclosed in square brackets and quoted.  This is a feature.
+
+   (2) This program was written before `gawk' acquired the ability to
+split each character in a string into separate array elements.  How
+might this ability simplify the program?
+
+
+File: gawk.info,  Node: Labels Program,  Next: Word Sorting,  Prev: Translate Program,  Up: Miscellaneous Programs
+
+Printing Mailing Labels
+-----------------------
+
+   Here is a "real world"(1) program.  This script reads lists of names
+and addresses, and generates mailing labels.  Each page of labels has
+20 labels on it, two across and ten down.  The addresses are guaranteed
+to be no more than five lines of data.  Each address is separated from
+the next by a blank line.
+
+   The basic idea is to read 20 labels worth of data.  Each line of
+each label is stored in the `line' array.  The single rule takes care
+of filling the `line' array and printing the page when 20 labels have
+been read.
+
+   The `BEGIN' rule simply sets `RS' to the empty string, so that `awk'
+will split records at blank lines (*note How Input is Split into
+Records: Records.).  It sets `MAXLINES' to 100, since `MAXLINE' is the
+maximum number of lines on the page (20 * 5 = 100).
+
+   Most of the work is done in the `printpage' function.  The label
+lines are stored sequentially in the `line' array.  But they have to be
+printed horizontally; `line[1]' next to `line[6]', `line[2]' next to
+`line[7]', and so on.  Two loops are used to accomplish this.  The
+outer loop, controlled by `i', steps through every 10 lines of data;
+this is each row of labels.  The inner loop, controlled by `j', goes
+through the lines within the row.  As `j' goes from zero to four, `i+j'
+is the `j''th line in the row, and `i+j+5' is the entry next to it.
+The output ends up looking something like this:
+
+     line 1          line 6
+     line 2          line 7
+     line 3          line 8
+     line 4          line 9
+     line 5          line 10
+
+   As a final note, at lines 21 and 61, an extra blank line is printed,
+to keep the output lined up on the labels.  This is dependent on the
+particular brand of labels in use when the program was written.  You
+will also note that there are two blank lines at the top and two blank
+lines at the bottom.
+
+   The `END' rule arranges to flush the final page of labels; there may
+not have been an even multiple of 20 labels in the data.
+
+     # labels.awk
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # June 1992
+     
+     # Program to print labels.  Each label is 5 lines of data
+     # that may have blank lines.  The label sheets have 2
+     # blank lines at the top and 2 at the bottom.
+     
+     BEGIN    { RS = "" ; MAXLINES = 100 }
+     
+     function printpage(    i, j)
+     {
+         if (Nlines <= 0)
+             return
+     
+         printf "\n\n"        # header
+     
+         for (i = 1; i <= Nlines; i += 10) {
+             if (i == 21 || i == 61)
+                 print ""
+             for (j = 0; j < 5; j++) {
+                 if (i + j > MAXLINES)
+                     break
+                 printf "   %-41s %s\n", line[i+j], line[i+j+5]
+             }
+             print ""
+         }
+     
+         printf "\n\n"        # footer
+     
+         for (i in line)
+             line[i] = ""
+     }
+     
+     # main rule
+     {
+         if (Count >= 20) {
+             printpage()
+             Count = 0
+             Nlines = 0
+         }
+         n = split($0, a, "\n")
+         for (i = 1; i <= n; i++)
+             line[++Nlines] = a[i]
+         for (; i <= 5; i++)
+             line[++Nlines] = ""
+         Count++
+     }
+     
+     END    \
+     {
+         printpage()
+     }
+
+   ---------- Footnotes ----------
+
+   (1) "Real world" is defined as "a program actually used to get
+something done."
+
+
+File: gawk.info,  Node: Word Sorting,  Next: History Sorting,  Prev: Labels Program,  Up: Miscellaneous Programs
+
+Generating Word Usage Counts
+----------------------------
+
+   The following `awk' program prints the number of occurrences of each
+word in its input.  It illustrates the associative nature of `awk'
+arrays by using strings as subscripts.  It also demonstrates the `for X
+in ARRAY' construction.  Finally, it shows how `awk' can be used in
+conjunction with other utility programs to do a useful task of some
+complexity with a minimum of effort.  Some explanations follow the
+program listing.
+
+     awk '
+     # Print list of word frequencies
+     {
+         for (i = 1; i <= NF; i++)
+             freq[$i]++
+     }
+     
+     END {
+         for (word in freq)
+             printf "%s\t%d\n", word, freq[word]
+     }'
+
+   The first thing to notice about this program is that it has two
+rules.  The first rule, because it has an empty pattern, is executed on
+every line of the input.  It uses `awk''s field-accessing mechanism
+(*note Examining Fields: Fields.) to pick out the individual words from
+the line, and the built-in variable `NF' (*note Built-in Variables::)
+to know how many fields are available.
+
+   For each input word, an element of the array `freq' is incremented to
+reflect that the word has been seen an additional time.
+
+   The second rule, because it has the pattern `END', is not executed
+until the input has been exhausted.  It prints out the contents of the
+`freq' table that has been built up inside the first action.
+
+   This program has several problems that would prevent it from being
+useful by itself on real text files:
+
+   * Words are detected using the `awk' convention that fields are
+     separated by whitespace and that other characters in the input
+     (except newlines) don't have any special meaning to `awk'.  This
+     means that punctuation characters count as part of words.
+
+   * The `awk' language considers upper- and lower-case characters to be
+     distinct.  Therefore, `bartender' and `Bartender' are not treated
+     as the same word.  This is undesirable since, in normal text, words
+     are capitalized if they begin sentences, and a frequency analyzer
+     should not be sensitive to capitalization.
+
+   * The output does not come out in any useful order.  You're more
+     likely to be interested in which words occur most frequently, or
+     having an alphabetized table of how frequently each word occurs.
+
+   The way to solve these problems is to use some of the more advanced
+features of the `awk' language.  First, we use `tolower' to remove case
+distinctions.  Next, we use `gsub' to remove punctuation characters.
+Finally, we use the system `sort' utility to process the output of the
+`awk' script.  Here is the new version of the program:
+
+     # Print list of word frequencies
+     {
+         $0 = tolower($0)    # remove case distinctions
+         gsub(/[^a-z0-9_ \t]/, "", $0)  # remove punctuation
+         for (i = 1; i <= NF; i++)
+             freq[$i]++
+     }
+     
+     END {
+         for (word in freq)
+             printf "%s\t%d\n", word, freq[word]
+     }
+
+   Assuming we have saved this program in a file named `wordfreq.awk',
+and that the data is in `file1', the following pipeline
+
+     awk -f wordfreq.awk file1 | sort +1 -nr
+
+produces a table of the words appearing in `file1' in order of
+decreasing frequency.
+
+   The `awk' program suitably massages the data and produces a word
+frequency table, which is not ordered.
+
+   The `awk' script's output is then sorted by the `sort' utility and
+printed on the terminal.  The options given to `sort' in this example
+specify to sort using the second field of each input line (skipping one
+field), that the sort keys should be treated as numeric quantities
+(otherwise `15' would come before `5'), and that the sorting should be
+done in descending (reverse) order.
+
+   We could have even done the `sort' from within the program, by
+changing the `END' action to:
+
+     END {
+         sort = "sort +1 -nr"
+         for (word in freq)
+             printf "%s\t%d\n", word, freq[word] | sort
+         close(sort)
+     }
+
+   You would have to use this way of sorting on systems that do not
+have true pipes.
+
+   See the general operating system documentation for more information
+on how to use the `sort' program.
+
+
+File: gawk.info,  Node: History Sorting,  Next: Extract Program,  Prev: Word Sorting,  Up: Miscellaneous Programs
+
+Removing Duplicates from Unsorted Text
+--------------------------------------
+
+   The `uniq' program (*note Printing Non-duplicated Lines of Text:
+Uniq Program.), removes duplicate lines from _sorted_ data.
+
+   Suppose, however, you need to remove duplicate lines from a data
+file, but that you wish to preserve the order the lines are in?  A good
+example of this might be a shell history file.  The history file keeps
+a copy of all the commands you have entered, and it is not unusual to
+repeat a command several times in a row.  Occasionally you might wish
+to compact the history by removing duplicate entries.  Yet it is
+desirable to maintain the order of the original commands.
+
+   This simple program does the job.  It uses two arrays.  The `data'
+array is indexed by the text of each line.  For each line, `data[$0]'
+is incremented.
+
+   If a particular line has not been seen before, then `data[$0]' will
+be zero.  In that case, the text of the line is stored in
+`lines[count]'.  Each element of `lines' is a unique command, and the
+indices of `lines' indicate the order in which those lines were
+encountered.  The `END' rule simply prints out the lines, in order.
+
+     # histsort.awk --- compact a shell history file
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     # Thanks to Byron Rakitzis for the general idea
+     {
+         if (data[$0]++ == 0)
+             lines[++count] = $0
+     }
+     
+     END {
+         for (i = 1; i <= count; i++)
+             print lines[i]
+     }
+
+   This program also provides a foundation for generating other useful
+information.  For example, using the following `print' satement in the
+`END' rule would indicate how often a particular command was used.
+
+     print data[lines[i]], lines[i]
+
+   This works because `data[$0]' was incremented each time a line was
+seen.
+
+
+File: gawk.info,  Node: Extract Program,  Next: Simple Sed,  Prev: History Sorting,  Up: Miscellaneous Programs
+
+Extracting Programs from Texinfo Source Files
+---------------------------------------------
+
+   The nodes *Note A Library of `awk' Functions: Library Functions, and
+*Note Practical `awk' Programs: Sample Programs, are the top level
+nodes for a large number of `awk' programs.  If you wish to experiment
+with these programs, it is tedious to have to type them in by hand.
+Here we present a program that can extract parts of a Texinfo input
+file into separate files.
+
+   This Info file is written in Texinfo, the GNU project's document
+formatting language.  A single Texinfo source file can be used to
+produce both printed and on-line documentation.  The Texinfo language
+is described fully, starting with *Note Introduction: (texi)Top.
+
+   For our purposes, it is enough to know three things about Texinfo
+input files.
+
+   * The "at" symbol, `@', is special in Texinfo, much like `\' in C or
+     `awk'.  Literal `@' symbols are represented in Texinfo source
+     files as `@@'.
+
+   * Comments start with either `@c' or `@comment'.  The file
+     extraction program will work by using special comments that start
+     at the beginning of a line.
+
+   * Example text that should not be split across a page boundary is
+     bracketed between lines containing `@group' and `@end group'
+     commands.
+
+   The following program, `extract.awk', reads through a Texinfo source
+file, and does two things, based on the special comments.  Upon seeing
+`@c system ...', it runs a command, by extracting the command text from
+the control line and passing it on to the `system' function (*note
+Built-in Functions for Input/Output: I/O Functions.).  Upon seeing `@c
+file FILENAME', each subsequent line is sent to the file FILENAME,
+until `@c endfile' is encountered.  The rules in `extract.awk' will
+match either `@c' or `@comment' by letting the `omment' part be
+optional.  Lines containing `@group' and `@end group' are simply
+removed.  `extract.awk' uses the `join' library function (*note Merging
+an Array Into a String: Join Function.).
+
+   The example programs in the on-line Texinfo source for `The GNU Awk
+User's Guide' (`gawk.texi') have all been bracketed inside `file', and
+`endfile' lines.  The `gawk' distribution uses a copy of `extract.awk'
+to extract the sample programs and install many of them in a standard
+directory, where `gawk' can find them.
+
+   `extract.awk' begins by setting `IGNORECASE' to one, so that mixed
+upper-case and lower-case letters in the directives won't matter.
+
+   The first rule handles calling `system', checking that a command was
+given (`NF' is at least three), and also checking that the command
+exited with a zero exit status, signifying OK.
+
+     # extract.awk --- extract files and run programs
+     #                 from texinfo files
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # May 1993
+     
+     BEGIN    { IGNORECASE = 1 }
+     
+     /^@c(omment)?[ \t]+system/    \
+     {
+         if (NF < 3) {
+             e = (FILENAME ":" FNR)
+             e = (e  ": badly formed `system' line")
+             print e > "/dev/stderr"
+             next
+         }
+         $1 = ""
+         $2 = ""
+         stat = system($0)
+         if (stat != 0) {
+             e = (FILENAME ":" FNR)
+             e = (e ": warning: system returned " stat)
+             print e > "/dev/stderr"
+         }
+     }
+
+The variable `e' is used so that the function fits nicely on the screen.
+
+   The second rule handles moving data into files.  It verifies that a
+file name was given in the directive.  If the file named is not the
+current file, then the current file is closed.  This means that an `@c
+endfile' was not given for that file.  (We should probably print a
+diagnostic in this case, although at the moment we do not.)
+
+   The `for' loop does the work.  It reads lines using `getline' (*note
+Explicit Input with `getline': Getline.).  For an unexpected end of
+file, it calls the `unexpected_eof' function.  If the line is an
+"endfile" line, then it breaks out of the loop.  If the line is an
+`@group' or `@end group' line, then it ignores it, and goes on to the
+next line.
+
+   Most of the work is in the following few lines.  If the line has no
+`@' symbols, it can be printed directly.  Otherwise, each leading `@'
+must be stripped off.
+
+   To remove the `@' symbols, the line is split into separate elements
+of the array `a', using the `split' function (*note Built-in Functions
+for String Manipulation: String Functions.).  Each element of `a' that
+is empty indicates two successive `@' symbols in the original line.
+For each two empty elements (`@@' in the original file), we have to add
+back in a single `@' symbol.
+
+   When the processing of the array is finished, `join' is called with
+the value of `SUBSEP', to rejoin the pieces back into a single line.
+That line is then printed to the output file.
+
+     /^@c(omment)?[ \t]+file/    \
+     {
+         if (NF != 3) {
+             e = (FILENAME ":" FNR ": badly formed `file' line")
+             print e > "/dev/stderr"
+             next
+         }
+         if ($3 != curfile) {
+             if (curfile != "")
+                 close(curfile)
+             curfile = $3
+         }
+     
+         for (;;) {
+             if ((getline line) <= 0)
+                 unexpected_eof()
+             if (line ~ /^@c(omment)?[ \t]+endfile/)
+                 break
+             else if (line ~ /^@(end[ \t]+)?group/)
+                 continue
+             if (index(line, "@") == 0) {
+                 print line > curfile
+                 continue
+             }
+             n = split(line, a, "@")
+             # if a[1] == "", means leading @,
+             # don't add one back in.
+             for (i = 2; i <= n; i++) {
+                 if (a[i] == "") { # was an @@
+                     a[i] = "@"
+                     if (a[i+1] == "")
+                         i++
+                 }
+             }
+             print join(a, 1, n, SUBSEP) > curfile
+         }
+     }
+
+   An important thing to note is the use of the `>' redirection.
+Output done with `>' only opens the file once; it stays open and
+subsequent output is appended to the file (*note Redirecting Output of
+`print' and `printf': Redirection.).  This allows us to easily mix
+program text and explanatory prose for the same sample source file (as
+has been done here!) without any hassle.  The file is only closed when
+a new data file name is encountered, or at the end of the input file.
+
+   Finally, the function `unexpected_eof' prints an appropriate error
+message and then exits.
+
+   The `END' rule handles the final cleanup, closing the open file.
+
+     function unexpected_eof()
+     {
+         printf("%s:%d: unexpected EOF or error\n", \
+             FILENAME, FNR) > "/dev/stderr"
+         exit 1
+     }
+     
+     END {
+         if (curfile)
+             close(curfile)
+     }
+
+
+File: gawk.info,  Node: Simple Sed,  Next: Igawk Program,  Prev: Extract Program,  Up: Miscellaneous Programs
+
+A Simple Stream Editor
+----------------------
+
+   The `sed' utility is a "stream editor," a program that reads a
+stream of data, makes changes to it, and passes the modified data on.
+It is often used to make global changes to a large file, or to a stream
+of data generated by a pipeline of commands.
+
+   While `sed' is a complicated program in its own right, its most
+common use is to perform global substitutions in the middle of a
+pipeline:
+
+     command1 < orig.data | sed 's/old/new/g' | command2 > result
+
+   Here, the `s/old/new/g' tells `sed' to look for the regexp `old' on
+each input line, and replace it with the text `new', globally (i.e. all
+the occurrences on a line).  This is similar to `awk''s `gsub' function
+(*note Built-in Functions for String Manipulation: String Functions.).
+
+   The following program, `awksed.awk', accepts at least two command
+line arguments; the pattern to look for and the text to replace it
+with. Any additional arguments are treated as data file names to
+process. If none are provided, the standard input is used.
+
+     # awksed.awk --- do s/foo/bar/g using just print
+     #    Thanks to Michael Brennan for the idea
+     
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # August 1995
+     
+     function usage()
+     {
+         print "usage: awksed pat repl [files...]" > "/dev/stderr"
+         exit 1
+     }
+     
+     BEGIN {
+         # validate arguments
+         if (ARGC < 3)
+             usage()
+     
+         RS = ARGV[1]
+         ORS = ARGV[2]
+     
+         # don't use arguments as files
+         ARGV[1] = ARGV[2] = ""
+     }
+     
+     # look ma, no hands!
+     {
+         if (RT == "")
+             printf "%s", $0
+         else
+             print
+     }
+
+   The program relies on `gawk''s ability to have `RS' be a regexp and
+on the setting of `RT' to the actual text that terminated the record
+(*note How Input is Split into Records: Records.).
+
+   The idea is to have `RS' be the pattern to look for. `gawk' will
+automatically set `$0' to the text between matches of the pattern.
+This is text that we wish to keep, unmodified.  Then, by setting `ORS'
+to the replacement text, a simple `print' statement will output the
+text we wish to keep, followed by the replacement text.
+
+   There is one wrinkle to this scheme, which is what to do if the last
+record doesn't end with text that matches `RS'?  Using a `print'
+statement unconditionally prints the replacement text, which is not
+correct.
+
+   However, if the file did not end in text that matches `RS', `RT'
+will be set to the null string.  In this case, we can print `$0' using
+`printf' (*note Using `printf' Statements for Fancier Printing:
+Printf.).
+
+   The `BEGIN' rule handles the setup, checking for the right number of
+arguments, and calling `usage' if there is a problem. Then it sets `RS'
+and `ORS' from the command line arguments, and sets `ARGV[1]' and
+`ARGV[2]' to the null string, so that they will not be treated as file
+names (*note Using `ARGC' and `ARGV': ARGC and ARGV.).
+
+   The `usage' function prints an error message and exits.
+
+   Finally, the single rule handles the printing scheme outlined above,
+using `print' or `printf' as appropriate, depending upon the value of
+`RT'.
+
+
+File: gawk.info,  Node: Igawk Program,  Prev: Simple Sed,  Up: Miscellaneous Programs
+
+An Easy Way to Use Library Functions
+------------------------------------
+
+   Using library functions in `awk' can be very beneficial. It
+encourages code re-use and the writing of general functions. Programs
+are smaller, and therefore clearer.  However, using library functions
+is only easy when writing `awk' programs; it is painful when running
+them, requiring multiple `-f' options.  If `gawk' is unavailable, then
+so too is the `AWKPATH' environment variable and the ability to put
+`awk' functions into a library directory (*note Command Line Options:
+Options.).
+
+   It would be nice to be able to write programs like so:
+
+     # library functions
+     @include getopt.awk
+     @include join.awk
+     ...
+     
+     # main program
+     BEGIN {
+         while ((c = getopt(ARGC, ARGV, "a:b:cde")) != -1)
+             ...
+         ...
+     }
+
+   The following program, `igawk.sh', provides this service.  It
+simulates `gawk''s searching of the `AWKPATH' variable, and also allows
+"nested" includes; i.e. a file that has been included with `@include'
+can contain further `@include' statements.  `igawk' will make an effort
+to only include files once, so that nested includes don't accidentally
+include a library function twice.
+
+   `igawk' should behave externally just like `gawk'.  This means it
+should accept all of `gawk''s command line arguments, including the
+ability to have multiple source files specified via `-f', and the
+ability to mix command line and library source files.
+
+   The program is written using the POSIX Shell (`sh') command language.
+The way the program works is as follows:
+
+  1. Loop through the arguments, saving anything that doesn't represent
+     `awk' source code for later, when the expanded program is run.
+
+  2. For any arguments that do represent `awk' text, put the arguments
+     into a temporary file that will be expanded.  There are two cases.
+
+       a. Literal text, provided with `--source' or `--source='.  This
+          text is just echoed directly.  The `echo' program will
+          automatically supply a trailing newline.
+
+       b. File names provided with `-f'.  We use a neat trick, and echo
+          `@include FILENAME' into the temporary file.  Since the file
+          inclusion program will work the way `gawk' does, this will
+          get the text of the file included into the program at the
+          correct point.
+
+  3. Run an `awk' program (naturally) over the temporary file to expand
+     `@include' statements.  The expanded program is placed in a second
+     temporary file.
+
+  4. Run the expanded program with `gawk' and any other original
+     command line arguments that the user supplied (such as the data
+     file names).
+
+   The initial part of the program turns on shell tracing if the first
+argument was `debug'.  Otherwise, a shell `trap' statement arranges to
+clean up any temporary files on program exit or upon an interrupt.
+
+   The next part loops through all the command line arguments.  There
+are several cases of interest.
+
+`--'
+     This ends the arguments to `igawk'.  Anything else should be
+     passed on to the user's `awk' program without being evaluated.
+
+`-W'
+     This indicates that the next option is specific to `gawk'.  To make
+     argument processing easier, the `-W' is appended to the front of
+     the remaining arguments and the loop continues.  (This is an `sh'
+     programming trick.  Don't worry about it if you are not familiar
+     with `sh'.)
+
+`-v'
+`-F'
+     These are saved and passed on to `gawk'.
+
+`-f'
+`--file'
+`--file='
+`-Wfile='
+     The file name is saved to the temporary file `/tmp/ig.s.$$' with an
+     `@include' statement.  The `sed' utility is used to remove the
+     leading option part of the argument (e.g., `--file=').
+
+`--source'
+`--source='
+`-Wsource='
+     The source text is echoed into `/tmp/ig.s.$$'.
+
+`--version'
+`--version'
+`-Wversion'
+     `igawk' prints its version number, and runs `gawk --version' to
+     get the `gawk' version information, and then exits.
+
+   If none of `-f', `--file', `-Wfile', `--source', or `-Wsource', were
+supplied, then the first non-option argument should be the `awk'
+program.  If there are no command line arguments left, `igawk' prints
+an error message and exits.  Otherwise, the first argument is echoed
+into `/tmp/ig.s.$$'.
+
+   In any case, after the arguments have been processed, `/tmp/ig.s.$$'
+contains the complete text of the original `awk' program.
+
+   The `$$' in `sh' represents the current process ID number.  It is
+often used in shell programs to generate unique temporary file names.
+This allows multiple users to run `igawk' without worrying that the
+temporary file names will clash.
+
+   Here's the program:
+
+     #! /bin/sh
+     
+     # igawk --- like gawk but do @include processing
+     # Arnold Robbins, arnold@gnu.ai.mit.edu, Public Domain
+     # July 1993
+     
+     if [ "$1" = debug ]
+     then
+         set -x
+         shift
+     else
+         # cleanup on exit, hangup, interrupt, quit, termination
+         trap 'rm -f /tmp/ig.[se].$$' 0 1 2 3 15
+     fi
+     
+     while [ $# -ne 0 ] # loop over arguments
+     do
+         case $1 in
+         --)     shift; break;;
+     
+         -W)     shift
+                 set -- -W"$@"
+                 continue;;
+     
+         -[vF])  opts="$opts $1 '$2'"
+                 shift;;
+     
+         -[vF]*) opts="$opts '$1'" ;;
+     
+         -f)     echo @include "$2" >> /tmp/ig.s.$$
+                 shift;;
+     
+         -f*)    f=`echo "$1" | sed 's/-f//'`
+                 echo @include "$f" >> /tmp/ig.s.$$ ;;
+     
+         -?file=*)    # -Wfile or --file
+                 f=`echo "$1" | sed 's/-.file=//'`
+                 echo @include "$f" >> /tmp/ig.s.$$ ;;
+     
+         -?file)    # get arg, $2
+                 echo @include "$2" >> /tmp/ig.s.$$
+                 shift;;
+     
+         -?source=*)    # -Wsource or --source
+                 t=`echo "$1" | sed 's/-.source=//'`
+                 echo "$t" >> /tmp/ig.s.$$ ;;
+     
+         -?source)  # get arg, $2
+                 echo "$2" >> /tmp/ig.s.$$
+                 shift;;
+     
+         -?version)
+                 echo igawk: version 1.0 1>&2
+                 gawk --version
+                 exit 0 ;;
+     
+         -[W-]*)    opts="$opts '$1'" ;;
+     
+         *)      break;;
+         esac
+         shift
+     done
+     
+     if [ ! -s /tmp/ig.s.$$ ]
+     then
+         if [ -z "$1" ]
+         then
+              echo igawk: no program! 1>&2
+              exit 1
+         else
+             echo "$1" > /tmp/ig.s.$$
+             shift
+         fi
+     fi
+     
+     # at this point, /tmp/ig.s.$$ has the program
+
+   The `awk' program to process `@include' directives reads through the
+program, one line at a time using `getline' (*note Explicit Input with
+`getline': Getline.).  The input file names and `@include' statements
+are managed using a stack.  As each `@include' is encountered, the
+current file name is "pushed" onto the stack, and the file named in the
+`@include' directive becomes the current file name.  As each file is
+finished, the stack is "popped," and the previous input file becomes
+the current input file again.  The process is started by making the
+original file the first one on the stack.
+
+   The `pathto' function does the work of finding the full path to a
+file.  It simulates `gawk''s behavior when searching the `AWKPATH'
+environment variable (*note The `AWKPATH' Environment Variable: AWKPATH
+Variable.).  If a file name has a `/' in it, no path search is done.
+Otherwise, the file name is concatenated with the name of each
+directory in the path, and an attempt is made to open the generated file
+name.  The only way in `awk' to test if a file can be read is to go
+ahead and try to read it with `getline'; that is what `pathto' does.
+If the file can be read, it is closed, and the file name is returned.
+
+     gawk -- '
+     # process @include directives
+     
+     function pathto(file,    i, t, junk)
+     {
+         if (index(file, "/") != 0)
+             return file
+     
+         for (i = 1; i <= ndirs; i++) {
+             t = (pathlist[i] "/" file)
+             if ((getline junk < t) > 0) {
+                 # found it
+                 close(t)
+                 return t
+             }
+         }
+         return ""
+     }
+
+   The main program is contained inside one `BEGIN' rule.  The first
+thing it does is set up the `pathlist' array that `pathto' uses.  After
+splitting the path on `:', null elements are replaced with `"."', which
+represents the current directory.
+
+     BEGIN {
+         path = ENVIRON["AWKPATH"]
+         ndirs = split(path, pathlist, ":")
+         for (i = 1; i <= ndirs; i++) {
+             if (pathlist[i] == "")
+                 pathlist[i] = "."
+         }
+
+   The stack is initialized with `ARGV[1]', which will be
+`/tmp/ig.s.$$'.  The main loop comes next.  Input lines are read in
+succession. Lines that do not start with `@include' are printed
+verbatim.
+
+   If the line does start with `@include', the file name is in `$2'.
+`pathto' is called to generate the full path.  If it could not, then we
+print an error message and continue.
+
+   The next thing to check is if the file has been included already.
+The `processed' array is indexed by the full file name of each included
+file, and it tracks this information for us.  If the file has been
+seen, a warning message is printed. Otherwise, the new file name is
+pushed onto the stack and processing continues.
+
+   Finally, when `getline' encounters the end of the input file, the
+file is closed and the stack is popped.  When `stackptr' is less than
+zero, the program is done.
+
+         stackptr = 0
+         input[stackptr] = ARGV[1] # ARGV[1] is first file
+     
+         for (; stackptr >= 0; stackptr--) {
+             while ((getline < input[stackptr]) > 0) {
+                 if (tolower($1) != "@include") {
+                     print
+                     continue
+                 }
+                 fpath = pathto($2)
+                 if (fpath == "") {
+                     printf("igawk:%s:%d: cannot find %s\n", \
+                         input[stackptr], FNR, $2) > "/dev/stderr"
+                     continue
+                 }
+                 if (! (fpath in processed)) {
+                     processed[fpath] = input[stackptr]
+                     input[++stackptr] = fpath
+                 } else
+                     print $2, "included in", input[stackptr], \
+                         "already included in", \
+                         processed[fpath] > "/dev/stderr"
+             }
+             close(input[stackptr])
+         }
+     }' /tmp/ig.s.$$ > /tmp/ig.e.$$
+
+   The last step is to call `gawk' with the expanded program and the
+original options and command line arguments that the user supplied.
+`gawk''s exit status is passed back on to `igawk''s calling program.
+
+     eval gawk -f /tmp/ig.e.$$ $opts -- "$@"
+     
+     exit $?
+
+   This version of `igawk' represents my third attempt at this program.
+There are three key simplifications that made the program work better.
+
+  1. Using `@include' even for the files named with `-f' makes building
+     the initial collected `awk' program much simpler; all the
+     `@include' processing can be done once.
+
+  2. The `pathto' function doesn't try to save the line read with
+     `getline' when testing for the file's accessibility.  Trying to
+     save this line for use with the main program complicates things
+     considerably.
+
+  3. Using a `getline' loop in the `BEGIN' rule does it all in one
+     place.  It is not necessary to call out to a separate loop for
+     processing nested `@include' statements.
+
+   Also, this program illustrates that it is often worthwhile to combine
+`sh' and `awk' programming together.  You can usually accomplish quite
+a lot, without having to resort to low-level programming in C or C++,
+and it is frequently easier to do certain kinds of string and argument
+manipulation using the shell than it is in `awk'.
+
+   Finally, `igawk' shows that it is not always necessary to add new
+features to a program; they can often be layered on top.  With `igawk',
+there is no real reason to build `@include' processing into `gawk'
+itself.
+
+   As an additional example of this, consider the idea of having two
+files in a directory in the search path.
+
+`default.awk'
+     This file would contain a set of default library functions, such
+     as `getopt' and `assert'.
+
+`site.awk'
+     This file would contain library functions that are specific to a
+     site or installation, i.e. locally developed functions.  Having a
+     separate file allows `default.awk' to change with new `gawk'
+     releases, without requiring the system administrator to update it
+     each time by adding the local functions.
+
+   One user suggested that `gawk' be modified to automatically read
+these files upon startup.  Instead, it would be very simple to modify
+`igawk' to do this. Since `igawk' can process nested `@include'
+directives, `default.awk' could simply contain `@include' statements
+for the desired library functions.
+
+
+File: gawk.info,  Node: Language History,  Next: Gawk Summary,  Prev: Sample Programs,  Up: Top
+
+The Evolution of the `awk' Language
+***********************************
+
+   This Info file describes the GNU implementation of `awk', which
+follows the POSIX specification.  Many `awk' users are only familiar
+with the original `awk' implementation in Version 7 Unix.  (This
+implementation was the basis for `awk' in Berkeley Unix, through
+4.3-Reno.  The 4.4 release of Berkeley Unix uses `gawk' 2.15.2 for its
+version of `awk'.) This chapter briefly describes the evolution of the
+`awk' language, with cross references to other parts of the Info file
+where you can find more information.
+
+* Menu:
+
+* V7/SVR3.1::                   The major changes between V7 and System V
+                                Release 3.1.
+* SVR4::                        Minor changes between System V Releases 3.1
+                                and 4.
+* POSIX::                       New features from the POSIX standard.
+* BTL::                         New features from the Bell Laboratories
+                                version of `awk'.
+* POSIX/GNU::                   The extensions in `gawk' not in POSIX
+                                `awk'.
+
+
+File: gawk.info,  Node: V7/SVR3.1,  Next: SVR4,  Prev: Language History,  Up: Language History
+
+Major Changes between V7 and SVR3.1
+===================================
+
+   The `awk' language evolved considerably between the release of
+Version 7 Unix (1978) and the new version first made generally
+available in System V Release 3.1 (1987).  This section summarizes the
+changes, with cross-references to further details.
+
+   * The requirement for `;' to separate rules on a line (*note `awk'
+     Statements Versus Lines: Statements/Lines.).
+
+   * User-defined functions, and the `return' statement (*note
+     User-defined Functions: User-defined.).
+
+   * The `delete' statement (*note The `delete' Statement: Delete.).
+
+   * The `do'-`while' statement (*note The `do'-`while' Statement: Do
+     Statement.).
+
+   * The built-in functions `atan2', `cos', `sin', `rand' and `srand'
+     (*note Numeric Built-in Functions: Numeric Functions.).
+
+   * The built-in functions `gsub', `sub', and `match' (*note Built-in
+     Functions for String Manipulation: String Functions.).
+
+   * The built-in functions `close', and `system' (*note Built-in
+     Functions for Input/Output: I/O Functions.).
+
+   * The `ARGC', `ARGV', `FNR', `RLENGTH', `RSTART', and `SUBSEP'
+     built-in variables (*note Built-in Variables::).
+
+   * The conditional expression using the ternary operator `?:' (*note
+     Conditional Expressions: Conditional Exp.).
+
+   * The exponentiation operator `^' (*note Arithmetic Operators:
+     Arithmetic Ops.) and its assignment operator form `^=' (*note
+     Assignment Expressions: Assignment Ops.).
+
+   * C-compatible operator precedence, which breaks some old `awk'
+     programs (*note Operator Precedence (How Operators Nest):
+     Precedence.).
+
+   * Regexps as the value of `FS' (*note Specifying How Fields are
+     Separated: Field Separators.), and as the third argument to the
+     `split' function (*note Built-in Functions for String
+     Manipulation: String Functions.).
+
+   * Dynamic regexps as operands of the `~' and `!~' operators (*note
+     How to Use Regular Expressions: Regexp Usage.).
+
+   * The escape sequences `\b', `\f', and `\r' (*note Escape
+     Sequences::).  (Some vendors have updated their old versions of
+     `awk' to recognize `\r', `\b', and `\f', but this is not something
+     you can rely on.)
+
+   * Redirection of input for the `getline' function (*note Explicit
+     Input with `getline': Getline.).
+
+   * Multiple `BEGIN' and `END' rules (*note The `BEGIN' and `END'
+     Special Patterns: BEGIN/END.).
+
+   * Multi-dimensional arrays (*note Multi-dimensional Arrays:
+     Multi-dimensional.).
+
+
+File: gawk.info,  Node: SVR4,  Next: POSIX,  Prev: V7/SVR3.1,  Up: Language History
+
+Changes between SVR3.1 and SVR4
+===============================
+
+   The System V Release 4 version of Unix `awk' added these features
+(some of which originated in `gawk'):
+
+   * The `ENVIRON' variable (*note Built-in Variables::).
+
+   * Multiple `-f' options on the command line (*note Command Line
+     Options: Options.).
+
+   * The `-v' option for assigning variables before program execution
+     begins (*note Command Line Options: Options.).
+
+   * The `--' option for terminating command line options.
+
+   * The `\a', `\v', and `\x' escape sequences (*note Escape
+     Sequences::).
+
+   * A defined return value for the `srand' built-in function (*note
+     Numeric Built-in Functions: Numeric Functions.).
+
+   * The `toupper' and `tolower' built-in string functions for case
+     translation (*note Built-in Functions for String Manipulation:
+     String Functions.).
+
+   * A cleaner specification for the `%c' format-control letter in the
+     `printf' function (*note Format-Control Letters: Control Letters.).
+
+   * The ability to dynamically pass the field width and precision
+     (`"%*.*d"') in the argument list of the `printf' function (*note
+     Format-Control Letters: Control Letters.).
+
+   * The use of regexp constants such as `/foo/' as expressions, where
+     they are equivalent to using the matching operator, as in `$0 ~
+     /foo/' (*note Using Regular Expression Constants: Using Constant
+     Regexps.).
+
+
+File: gawk.info,  Node: POSIX,  Next: BTL,  Prev: SVR4,  Up: Language History
+
+Changes between SVR4 and POSIX `awk'
+====================================
+
+   The POSIX Command Language and Utilities standard for `awk'
+introduced the following changes into the language:
+
+   * The use of `-W' for implementation-specific options.
+
+   * The use of `CONVFMT' for controlling the conversion of numbers to
+     strings (*note Conversion of Strings and Numbers: Conversion.).
+
+   * The concept of a numeric string, and tighter comparison rules to go
+     with it (*note Variable Typing and Comparison Expressions: Typing
+     and Comparison.).
+
+   * More complete documentation of many of the previously undocumented
+     features of the language.
+
+   The following common extensions are not permitted by the POSIX
+standard:
+
+   * `\x' escape sequences are not recognized (*note Escape
+     Sequences::).
+
+   * Newlines do not act as whitespace to separate fields when `FS' is
+     equal to a single space.
+
+   * The synonym `func' for the keyword `function' is not recognized
+     (*note Function Definition Syntax: Definition Syntax.).
+
+   * The operators `**' and `**=' cannot be used in place of `^' and
+     `^=' (*note Arithmetic Operators: Arithmetic Ops., and also *note
+     Assignment Expressions: Assignment Ops.).
+
+   * Specifying `-Ft' on the command line does not set the value of
+     `FS' to be a single tab character (*note Specifying How Fields are
+     Separated: Field Separators.).
+
+   * The `fflush' built-in function is not supported (*note Built-in
+     Functions for Input/Output: I/O Functions.).
+
+
+File: gawk.info,  Node: BTL,  Next: POSIX/GNU,  Prev: POSIX,  Up: Language History
+
+Extensions in the Bell Laboratories `awk'
+=========================================
+
+   Brian Kernighan, one of the original designers of Unix `awk', has
+made his version available via anonymous `ftp' (*note Other Freely
+Available `awk' Implementations: Other Versions.).  This section
+describes extensions in his version of `awk' that are not in POSIX
+`awk'.
+
+   * The `-mf NNN' and `-mr NNN' command line options to set the
+     maximum number of fields, and the maximum record size, respectively
+     (*note Command Line Options: Options.).
+
+   * The `fflush' built-in function for flushing buffered output (*note
+     Built-in Functions for Input/Output: I/O Functions.).
+
+
+
+File: gawk.info,  Node: POSIX/GNU,  Prev: BTL,  Up: Language History
+
+Extensions in `gawk' Not in POSIX `awk'
+=======================================
+
+   The GNU implementation, `gawk', adds a number of features.  This
+sections lists them in the order they were added to `gawk'.  They can
+all be disabled with either the `--traditional' or `--posix' options
+(*note Command Line Options: Options.).
+
+   Version 2.10 of `gawk' introduced these features:
+
+   * The `AWKPATH' environment variable for specifying a path search for
+     the `-f' command line option (*note Command Line Options:
+     Options.).
+
+   * The `IGNORECASE' variable and its effects (*note Case-sensitivity
+     in Matching: Case-sensitivity.).
+
+   * The `/dev/stdin', `/dev/stdout', `/dev/stderr', and `/dev/fd/N'
+     file name interpretation (*note Special File Names in `gawk':
+     Special Files.).
+
+   Version 2.13 of `gawk' introduced these features:
+
+   * The `FIELDWIDTHS' variable and its effects (*note Reading
+     Fixed-width Data: Constant Size.).
+
+   * The `systime' and `strftime' built-in functions for obtaining and
+     printing time stamps (*note Functions for Dealing with Time
+     Stamps: Time Functions.).
+
+   * The `-W lint' option to provide source code and run time error and
+     portability checking (*note Command Line Options: Options.).
+
+   * The `-W compat' option to turn off these extensions (*note Command
+     Line Options: Options.).
+
+   * The `-W posix' option for full POSIX compliance (*note Command
+     Line Options: Options.).
+
+   Version 2.14 of `gawk' introduced these features:
+
+   * The `next file' statement for skipping to the next data file
+     (*note The `nextfile' Statement: Nextfile Statement.).
+
+   Version 2.15 of `gawk' introduced these features:
+
+   * The `ARGIND' variable, that tracks the movement of `FILENAME'
+     through `ARGV'  (*note Built-in Variables::).
+
+   * The `ERRNO' variable, that contains the system error message when
+     `getline' returns -1, or when `close' fails (*note Built-in
+     Variables::).
+
+   * The ability to use GNU-style long named options that start with
+     `--' (*note Command Line Options: Options.).
+
+   * The `--source' option for mixing command line and library file
+     source code (*note Command Line Options: Options.).
+
+   * The `/dev/pid', `/dev/ppid', `/dev/pgrpid', and `/dev/user' file
+     name interpretation (*note Special File Names in `gawk': Special
+     Files.).
+
+   Version 3.0 of `gawk' introduced these features:
+
+   * The `next file' statement became `nextfile' (*note The `nextfile'
+     Statement: Nextfile Statement.).
+
+   * The `--lint-old' option to warn about constructs that are not
+     available in the original Version 7 Unix version of `awk' (*note
+     Major Changes between V7 and SVR3.1: V7/SVR3.1.).
+
+   * The `--traditional' option was added as a better name for
+     `--compat' (*note Command Line Options: Options.).
+
+   * The ability for `FS' to be a null string, and for the third
+     argument to `split' to be the null string (*note Making Each
+     Character a Separate Field: Single Character Fields.).
+
+   * The ability for `RS' to be a regexp (*note How Input is Split into
+     Records: Records.).
+
+   * The `RT' variable (*note How Input is Split into Records:
+     Records.).
+
+   * The `gensub' function for more powerful text manipulation (*note
+     Built-in Functions for String Manipulation: String Functions.).
+
+   * The `strftime' function acquired a default time format, allowing
+     it to be called with no arguments (*note Functions for Dealing
+     with Time Stamps: Time Functions.).
+
+   * Full support for both POSIX and GNU regexps (*note Regular
+     Expressions: Regexp.).
+
+   * The `--re-interval' option to provide interval expressions in
+     regexps (*note Regular Expression Operators: Regexp Operators.).
+
+   * `IGNORECASE' changed, now applying to string comparison as well as
+     regexp operations (*note Case-sensitivity in Matching:
+     Case-sensitivity.).
+
+   * The `-m' option and the `fflush' function from the Bell Labs
+     research version of `awk' (*note Command Line Options: Options.;
+     also *note Built-in Functions for Input/Output: I/O Functions.).
+
+   * The use of GNU Autoconf to control the configuration process
+     (*note Compiling `gawk' for Unix: Quick Installation.).
+
+   * Amiga support (*note Installing `gawk' on an Amiga: Amiga
+     Installation.).
+
+
+
+File: gawk.info,  Node: Gawk Summary,  Next: Installation,  Prev: Language History,  Up: Top
+
+`gawk' Summary
+**************
+
+   This appendix provides a brief summary of the `gawk' command line
+and the `awk' language.  It is designed to serve as "quick reference."
+It is therefore terse, but complete.
+
+* Menu:
+
+* Command Line Summary::        Recapitulation of the command line.
+* Language Summary::            A terse review of the language.
+* Variables/Fields::            Variables, fields, and arrays.
+* Rules Summary::               Patterns and Actions, and their component
+                                parts.
+* Actions Summary::             Quick overview of actions.
+* Functions Summary::           Defining and calling functions.
+* Historical Features::         Some undocumented but supported ``features''.
+
+
+File: gawk.info,  Node: Command Line Summary,  Next: Language Summary,  Prev: Gawk Summary,  Up: Gawk Summary
+
+Command Line Options Summary
+============================
+
+   The command line consists of options to `gawk' itself, the `awk'
+program text (if not supplied via the `-f' option), and values to be
+made available in the `ARGC' and `ARGV' predefined `awk' variables:
+
+     gawk [POSIX OR GNU STYLE OPTIONS] -f SOURCE-FILE [`--'] FILE ...
+     gawk [POSIX OR GNU STYLE OPTIONS] [`--'] 'PROGRAM' FILE ...
+
+   The options that `gawk' accepts are:
+
+`-F FS'
+`--field-separator FS'
+     Use FS for the input field separator (the value of the `FS'
+     predefined variable).
+
+`-f PROGRAM-FILE'
+`--file PROGRAM-FILE'
+     Read the `awk' program source from the file PROGRAM-FILE, instead
+     of from the first command line argument.
+
+`-mf NNN'
+`-mr NNN'
+     The `f' flag sets the maximum number of fields, and the `r' flag
+     sets the maximum record size.  These options are ignored by
+     `gawk', since `gawk' has no predefined limits; they are only for
+     compatibility with the Bell Labs research version of Unix `awk'.
+
+`-v VAR=VAL'
+`--assign VAR=VAL'
+     Assign the variable VAR the value VAL before program execution
+     begins.
+
+`-W traditional'
+`-W compat'
+`--traditional'
+`--compat'
+     Use compatibility mode, in which `gawk' extensions are turned off.
+
+`-W copyleft'
+`-W copyright'
+`--copyleft'
+`--copyright'
+     Print the short version of the General Public License on the
+     standard output, and exit.  This option may disappear in a future
+     version of `gawk'.
+
+`-W help'
+`-W usage'
+`--help'
+`--usage'
+     Print a relatively short summary of the available options on the
+     standard output, and exit.
+
+`-W lint'
+`--lint'
+     Give warnings about dubious or non-portable `awk' constructs.
+
+`-W lint-old'
+`--lint-old'
+     Warn about constructs that are not available in the original
+     Version 7 Unix version of `awk'.
+
+`-W posix'
+`--posix'
+     Use POSIX compatibility mode, in which `gawk' extensions are
+     turned off and additional restrictions apply.
+
+`-W re-interval'
+`--re-interval'
+     Allow interval expressions (*note Regular Expression Operators:
+     Regexp Operators.), in regexps.
+
+`-W source=PROGRAM-TEXT'
+`--source PROGRAM-TEXT'
+     Use PROGRAM-TEXT as `awk' program source code.  This option allows
+     mixing command line source code with source code from files, and is
+     particularly useful for mixing command line programs with library
+     functions.
+
+`-W version'
+`--version'
+     Print version information for this particular copy of `gawk' on
+     the error output.
+
+`--'
+     Signal the end of options.  This is useful to allow further
+     arguments to the `awk' program itself to start with a `-'.  This
+     is mainly for consistency with POSIX argument parsing conventions.
+
+   Any other options are flagged as invalid, but are otherwise ignored.
+*Note Command Line Options: Options, for more details.
+
+
+File: gawk.info,  Node: Language Summary,  Next: Variables/Fields,  Prev: Command Line Summary,  Up: Gawk Summary
+
+Language Summary
+================
+
+   An `awk' program consists of a sequence of zero or more
+pattern-action statements and optional function definitions.  One or
+the other of the pattern and action may be omitted.
+
+     PATTERN    { ACTION STATEMENTS }
+     PATTERN
+               { ACTION STATEMENTS }
+     
+     function NAME(PARAMETER LIST)     { ACTION STATEMENTS }
+
+   `gawk' first reads the program source from the PROGRAM-FILE(s), if
+specified, or from the first non-option argument on the command line.
+The `-f' option may be used multiple times on the command line.  `gawk'
+reads the program text from all the PROGRAM-FILE files, effectively
+concatenating them in the order they are specified.  This is useful for
+building libraries of `awk' functions, without having to include them
+in each new `awk' program that uses them.  To use a library function in
+a file from a program typed in on the command line, specify `--source
+'PROGRAM'', and type your program in between the single quotes.  *Note
+Command Line Options: Options.
+
+   The environment variable `AWKPATH' specifies a search path to use
+when finding source files named with the `-f' option.  The default
+path, which is `.:/usr/local/share/awk'(1) is used if `AWKPATH' is not
+set.  If a file name given to the `-f' option contains a `/' character,
+no path search is performed.  *Note The `AWKPATH' Environment Variable:
+AWKPATH Variable.
+
+   `gawk' compiles the program into an internal form, and then proceeds
+to read each file named in the `ARGV' array.  The initial values of
+`ARGV' come from the command line arguments.  If there are no files
+named on the command line, `gawk' reads the standard input.
+
+   If a "file" named on the command line has the form `VAR=VAL', it is
+treated as a variable assignment: the variable VAR is assigned the
+value VAL.  If any of the files have a value that is the null string,
+that element in the list is skipped.
+
+   For each record in the input, `gawk' tests to see if it matches any
+PATTERN in the `awk' program.  For each pattern that the record
+matches, the associated ACTION is executed.
+
+   ---------- Footnotes ----------
+
+   (1) The path may use a directory other than `/usr/local/share/awk',
+depending upon how `gawk' was built and installed.
+
+
+File: gawk.info,  Node: Variables/Fields,  Next: Rules Summary,  Prev: Language Summary,  Up: Gawk Summary
+
+Variables and Fields
+====================
+
+   `awk' variables are not declared; they come into existence when they
+are first used.  Their values are either floating-point numbers or
+strings.  `awk' also has one-dimensional arrays; multiple-dimensional
+arrays may be simulated.  There are several predefined variables that
+`awk' sets as a program runs; these are summarized below.
+
+* Menu:
+
+* Fields Summary::              Input field splitting.
+* Built-in Summary::            `awk''s built-in variables.
+* Arrays Summary::              Using arrays.
+* Data Type Summary::           Values in `awk' are numbers or strings.
+
+
+File: gawk.info,  Node: Fields Summary,  Next: Built-in Summary,  Prev: Variables/Fields,  Up: Variables/Fields
+
+Fields
+------
+
+   As each input line is read, `gawk' splits the line into FIELDS,
+using the value of the `FS' variable as the field separator.  If `FS'
+is a single character, fields are separated by that character.
+Otherwise, `FS' is expected to be a full regular expression.  In the
+special case that `FS' is a single space, fields are separated by runs
+of spaces, tabs and/or newlines.(1) If `FS' is the null string (`""'),
+then each individual character in the record becomes a separate field.
+Note that the value of `IGNORECASE' (*note Case-sensitivity in
+Matching: Case-sensitivity.)  also affects how fields are split when
+`FS' is a regular expression.
+
+   Each field in the input line may be referenced by its position, `$1',
+`$2', and so on.  `$0' is the whole line.  The value of a field may be
+assigned to as well.  Field numbers need not be constants:
+
+     n = 5
+     print $n
+
+prints the fifth field in the input line.  The variable `NF' is set to
+the total number of fields in the input line.
+
+   References to non-existent fields (i.e. fields after `$NF') return
+the null string.  However, assigning to a non-existent field (e.g.,
+`$(NF+2) = 5') increases the value of `NF', creates any intervening
+fields with the null string as their value, and causes the value of
+`$0' to be recomputed, with the fields being separated by the value of
+`OFS'.  Decrementing `NF' causes the values of fields past the new
+value to be lost, and the value of `$0' to be recomputed, with the
+fields being separated by the value of `OFS'.  *Note Reading Input
+Files: Reading Files.
+
+   ---------- Footnotes ----------
+
+   (1) In POSIX `awk', newline does not separate fields.
+
+
+File: gawk.info,  Node: Built-in Summary,  Next: Arrays Summary,  Prev: Fields Summary,  Up: Variables/Fields
+
+Built-in Variables
+------------------
+
+   `gawk''s built-in variables are:
+
+`ARGC'
+     The number of elements in `ARGV'. See below for what is actually
+     included in `ARGV'.
+
+`ARGIND'
+     The index in `ARGV' of the current file being processed.  When
+     `gawk' is processing the input data files, it is always true that
+     `FILENAME == ARGV[ARGIND]'.
+
+`ARGV'
+     The array of command line arguments.  The array is indexed from
+     zero to `ARGC' - 1.  Dynamically changing `ARGC' and the contents
+     of `ARGV' can control the files used for data.  A null-valued
+     element in `ARGV' is ignored. `ARGV' does not include the options
+     to `awk' or the text of the `awk' program itself.
+
+`CONVFMT'
+     The conversion format to use when converting numbers to strings.
+
+`FIELDWIDTHS'
+     A space separated list of numbers describing the fixed-width input
+     data.
+
+`ENVIRON'
+     An array of environment variable values.  The array is indexed by
+     variable name, each element being the value of that variable.
+     Thus, the environment variable `HOME' is `ENVIRON["HOME"]'.  One
+     possible value might be `/home/arnold'.
+
+     Changing this array does not affect the environment seen by
+     programs which `gawk' spawns via redirection or the `system'
+     function.  (This may change in a future version of `gawk'.)
+
+     Some operating systems do not have environment variables.  The
+     `ENVIRON' array is empty when running on these systems.
+
+`ERRNO'
+     The system error message when an error occurs using `getline' or
+     `close'.
+
+`FILENAME'
+     The name of the current input file.  If no files are specified on
+     the command line, the value of `FILENAME' is the null string.
+
+`FNR'
+     The input record number in the current input file.
+
+`FS'
+     The input field separator, a space by default.
+
+`IGNORECASE'
+     The case-sensitivity flag for string comparisons and regular
+     expression operations.  If `IGNORECASE' has a non-zero value, then
+     pattern matching in rules, record separating with `RS', field
+     splitting with `FS', regular expression matching with `~' and
+     `!~', and the `gensub', `gsub', `index', `match', `split' and
+     `sub' built-in functions all ignore case when doing regular
+     expression operations, and all string comparisons are done
+     ignoring case.
+
+`NF'
+     The number of fields in the current input record.
+
+`NR'
+     The total number of input records seen so far.
+
+`OFMT'
+     The output format for numbers for the `print' statement, `"%.6g"'
+     by default.
+
+`OFS'
+     The output field separator, a space by default.
+
+`ORS'
+     The output record separator, by default a newline.
+
+`RS'
+     The input record separator, by default a newline.  If `RS' is set
+     to the null string, then records are separated by blank lines.
+     When `RS' is set to the null string, then the newline character
+     always acts as a field separator, in addition to whatever value
+     `FS' may have.  If `RS' is set to a multi-character string, it
+     denotes a regexp; input text matching the regexp separates records.
+
+`RT'
+     The input text that matched the text denoted by `RS', the record
+     separator.
+
+`RSTART'
+     The index of the first character last matched by `match'; zero if
+     no match.
+
+`RLENGTH'
+     The length of the string last matched by `match'; -1 if no match.
+
+`SUBSEP'
+     The string used to separate multiple subscripts in array elements,
+     by default `"\034"'.
+
+   *Note Built-in Variables::, for more information.
+
+
+File: gawk.info,  Node: Arrays Summary,  Next: Data Type Summary,  Prev: Built-in Summary,  Up: Variables/Fields
+
+Arrays
+------
+
+   Arrays are subscripted with an expression between square brackets
+(`[' and `]').  Array subscripts are _always_ strings; numbers are
+converted to strings as necessary, following the standard conversion
+rules (*note Conversion of Strings and Numbers: Conversion.).
+
+   If you use multiple expressions separated by commas inside the square
+brackets, then the array subscript is a string consisting of the
+concatenation of the individual subscript values, converted to strings,
+separated by the subscript separator (the value of `SUBSEP').
+
+   The special operator `in' may be used in a conditional context to
+see if an array has an index consisting of a particular value.
+
+     if (val in array)
+             print array[val]
+
+   If the array has multiple subscripts, use `(i, j, ...) in ARRAY' to
+test for existence of an element.
+
+   The `in' construct may also be used in a `for' loop to iterate over
+all the elements of an array.  *Note Scanning All Elements of an Array:
+Scanning an Array.
+
+   You can remove an element from an array using the `delete' statement.
+
+   You can clear an entire array using `delete ARRAY'.
+
+   *Note Arrays in `awk': Arrays.
+
+
+File: gawk.info,  Node: Data Type Summary,  Prev: Arrays Summary,  Up: Variables/Fields
+
+Data Types
+----------
+
+   The value of an `awk' expression is always either a number or a
+string.
+
+   Some contexts (such as arithmetic operators) require numeric values.
+They convert strings to numbers by interpreting the text of the string
+as a number.  If the string does not look like a number, it converts to
+zero.
+
+   Other contexts (such as concatenation) require string values.  They
+convert numbers to strings by effectively printing them with `sprintf'.
+*Note Conversion of Strings and Numbers: Conversion, for the details.
+
+   To force conversion of a string value to a number, simply add zero
+to it.  If the value you start with is already a number, this does not
+change it.
+
+   To force conversion of a numeric value to a string, concatenate it
+with the null string.
+
+   Comparisons are done numerically if both operands are numeric, or if
+one is numeric and the other is a numeric string.  Otherwise one or
+both operands are converted to strings and a string comparison is
+performed.  Fields, `getline' input, `FILENAME', `ARGV' elements,
+`ENVIRON' elements and the elements of an array created by `split' are
+the only items that can be numeric strings. String constants, such as
+`"3.1415927"' are not numeric strings, they are string constants.  The
+full rules for comparisons are described in *Note Variable Typing and
+Comparison Expressions: Typing and Comparison.
+
+   Uninitialized variables have the string value `""' (the null, or
+empty, string).  In contexts where a number is required, this is
+equivalent to zero.
+
+   *Note Variables::, for more information on variable naming and
+initialization; *note Conversion of Strings and Numbers: Conversion.,
+for more information on how variable values are interpreted.
+
+
+File: gawk.info,  Node: Rules Summary,  Next: Actions Summary,  Prev: Variables/Fields,  Up: Gawk Summary
+
+Patterns
+========
+
+* Menu:
+
+* Pattern Summary::             Quick overview of patterns.
+* Regexp Summary::              Quick overview of regular expressions.
+
+   An `awk' program is mostly composed of rules, each consisting of a
+pattern followed by an action.  The action is enclosed in `{' and `}'.
+Either the pattern may be missing, or the action may be missing, but
+not both.  If the pattern is missing, the action is executed for every
+input record.  A missing action is equivalent to `{ print }', which
+prints the entire line.
+
+   Comments begin with the `#' character, and continue until the end of
+the line.  Blank lines may be used to separate statements.  Statements
+normally end with a newline; however, this is not the case for lines
+ending in a `,', `{', `?', `:', `&&', or `||'.  Lines ending in `do' or
+`else' also have their statements automatically continued on the
+following line.  In other cases, a line can be continued by ending it
+with a `\', in which case the newline is ignored.
+
+   Multiple statements may be put on one line by separating each one
+with a `;'.  This applies to both the statements within the action part
+of a rule (the usual case), and to the rule statements.
+
+   *Note Comments in `awk' Programs: Comments, for information on
+`awk''s commenting convention; *note `awk' Statements Versus Lines:
+Statements/Lines., for a description of the line continuation mechanism
+in `awk'.
+
+
+File: gawk.info,  Node: Pattern Summary,  Next: Regexp Summary,  Prev: Rules Summary,  Up: Rules Summary
+
+Pattern Summary
+---------------
+
+   `awk' patterns may be one of the following:
+
+     /REGULAR EXPRESSION/
+     RELATIONAL EXPRESSION
+     PATTERN && PATTERN
+     PATTERN || PATTERN
+     PATTERN ? PATTERN : PATTERN
+     (PATTERN)
+     ! PATTERN
+     PATTERN1, PATTERN2
+     BEGIN
+     END
+
+   `BEGIN' and `END' are two special kinds of patterns that are not
+tested against the input.  The action parts of all `BEGIN' rules are
+concatenated as if all the statements had been written in a single
+`BEGIN' rule.  They are executed before any of the input is read.
+Similarly, all the `END' rules are concatenated, and executed when all
+the input is exhausted (or when an `exit' statement is executed).
+`BEGIN' and `END' patterns cannot be combined with other patterns in
+pattern expressions.  `BEGIN' and `END' rules cannot have missing
+action parts.
+
+   For `/REGULAR-EXPRESSION/' patterns, the associated statement is
+executed for each input record that matches the regular expression.
+Regular expressions are summarized below.
+
+   A RELATIONAL EXPRESSION may use any of the operators defined below in
+the section on actions.  These generally test whether certain fields
+match certain regular expressions.
+
+   The `&&', `||', and `!' operators are logical "and," logical "or,"
+and logical "not," respectively, as in C.  They do short-circuit
+evaluation, also as in C, and are used for combining more primitive
+pattern expressions.  As in most languages, parentheses may be used to
+change the order of evaluation.
+
+   The `?:' operator is like the same operator in C.  If the first
+pattern matches, then the second pattern is matched against the input
+record; otherwise, the third is matched.  Only one of the second and
+third patterns is matched.
+
+   The `PATTERN1, PATTERN2' form of a pattern is called a range
+pattern.  It matches all input lines starting with a line that matches
+PATTERN1, and continuing until a line that matches PATTERN2, inclusive.
+A range pattern cannot be used as an operand of any of the pattern
+operators.
+
+   *Note Pattern Elements: Pattern Overview.
+
+
+File: gawk.info,  Node: Regexp Summary,  Prev: Pattern Summary,  Up: Rules Summary
+
+Regular Expressions
+-------------------
+
+   Regular expressions are based on POSIX EREs (extended regular
+expressions).  The escape sequences allowed in string constants are
+also valid in regular expressions (*note Escape Sequences::).  Regexps
+are composed of characters as follows:
+
+`C'
+     matches the character C (assuming C is none of the characters
+     listed below).
+
+`\C'
+     matches the literal character C.
+
+`.'
+     matches any character, _including_ newline.  In strict POSIX mode,
+     `.' does not match the NUL character, which is a character with
+     all bits equal to zero.
+
+`^'
+     matches the beginning of a string.
+
+`$'
+     matches the end of a string.
+
+`[ABC...]'
+     matches any of the characters ABC... (character list).
+
+`[[:CLASS:]]'
+     matches any character in the character class CLASS. Allowable
+     classes are `alnum', `alpha', `blank', `cntrl', `digit', `graph',
+     `lower', `print', `punct', `space', `upper', and `xdigit'.
+
+`[[.SYMBOL.]]'
+     matches the multi-character collating symbol SYMBOL.  `gawk' does
+     not currently support collating symbols.
+
+`[[=CLASSNAME=]]'
+     matches any of the equivalent characters in the current locale
+     named by the equivalence class CLASSNAME.  `gawk' does not
+     currently support equivalence classes.
+
+`[^ABC...]'
+     matches any character except ABC... (negated character list).
+
+`R1|R2'
+     matches either R1 or R2 (alternation).
+
+`R1R2'
+     matches R1, and then R2 (concatenation).
+
+`R+'
+     matches one or more R's.
+
+`R*'
+     matches zero or more R's.
+
+`R?'
+     matches zero or one R's.
+
+`(R)'
+     matches R (grouping).
+
+`R{N}'
+`R{N,}'
+`R{N,M}'
+     matches at least N, N to any number, or N to M occurrences of R
+     (interval expressions).
+
+`\y'
+     matches the empty string at either the beginning or the end of a
+     word.
+
+`\B'
+     matches the empty string within a word.
+
+`\<'
+     matches the empty string at the beginning of a word.
+
+`\>'
+     matches the empty string at the end of a word.
+
+`\w'
+     matches any word-constituent character (alphanumeric characters and
+     the underscore).
+
+`\W'
+     matches any character that is not word-constituent.
+
+`\`'
+     matches the empty string at the beginning of a buffer (same as a
+     string in `gawk').
+
+`\''
+     matches the empty string at the end of a buffer.
+
+   The various command line options control how `gawk' interprets
+characters in regexps.
+
+No options
+     In the default case, `gawk' provide all the facilities of POSIX
+     regexps and the GNU regexp operators described above.  However,
+     interval expressions are not supported.
+
+`--posix'
+     Only POSIX regexps are supported, the GNU operators are not special
+     (e.g., `\w' matches a literal `w').  Interval expressions are
+     allowed.
+
+`--traditional'
+     Traditional Unix `awk' regexps are matched. The GNU operators are
+     not special, interval expressions are not available, and neither
+     are the POSIX character classes (`[[:alnum:]]' and so on).
+     Characters described by octal and hexadecimal escape sequences are
+     treated literally, even if they represent regexp metacharacters.
+
+`--re-interval'
+     Allow interval expressions in regexps, even if `--traditional' has
+     been provided.
+
+   *Note Regular Expressions: Regexp.
+
+
+File: gawk.info,  Node: Actions Summary,  Next: Functions Summary,  Prev: Rules Summary,  Up: Gawk Summary
+
+Actions
+=======
+
+   Action statements are enclosed in braces, `{' and `}'.  A missing
+action statement is equivalent to `{ print }'.
+
+   Action statements consist of the usual assignment, conditional, and
+looping statements found in most languages.  The operators, control
+statements, and Input/Output statements available are similar to those
+in C.
+
+   Comments begin with the `#' character, and continue until the end of
+the line.  Blank lines may be used to separate statements.  Statements
+normally end with a newline; however, this is not the case for lines
+ending in a `,', `{', `?', `:', `&&', or `||'.  Lines ending in `do' or
+`else' also have their statements automatically continued on the
+following line.  In other cases, a line can be continued by ending it
+with a `\', in which case the newline is ignored.
+
+   Multiple statements may be put on one line by separating each one
+with a `;'.  This applies to both the statements within the action part
+of a rule (the usual case), and to the rule statements.
+
+   *Note Comments in `awk' Programs: Comments, for information on
+`awk''s commenting convention; *note `awk' Statements Versus Lines:
+Statements/Lines., for a description of the line continuation mechanism
+in `awk'.
+
+* Menu:
+
+* Operator Summary::            `awk' operators.
+* Control Flow Summary::        The control statements.
+* I/O Summary::                 The I/O statements.
+* Printf Summary::              A summary of `printf'.
+* Special File Summary::        Special file names interpreted internally.
+* Built-in Functions Summary::  Built-in numeric and string functions.
+* Time Functions Summary::      Built-in time functions.
+* String Constants Summary::    Escape sequences in strings.
+
+
+File: gawk.info,  Node: Operator Summary,  Next: Control Flow Summary,  Prev: Actions Summary,  Up: Actions Summary
+
+Operators
+---------
+
+   The operators in `awk', in order of decreasing precedence, are:
+
+`(...)'
+     Grouping.
+
+`$'
+     Field reference.
+
+`++ --'
+     Increment and decrement, both prefix and postfix.
+
+`^'
+     Exponentiation (`**' may also be used, and `**=' for the assignment
+     operator, but they are not specified in the POSIX standard).
+
+`+ - !'
+     Unary plus, unary minus, and logical negation.
+
+`* / %'
+     Multiplication, division, and modulus.
+
+`+ -'
+     Addition and subtraction.
+
+`SPACE'
+     String concatenation.
+
+`< <= > >= != =='
+     The usual relational operators.
+
+`~ !~'
+     Regular expression match, negated match.
+
+`in'
+     Array membership.
+
+`&&'
+     Logical "and".
+
+`||'
+     Logical "or".
+
+`?:'
+     A conditional expression.  This has the form `EXPR1 ?  EXPR2 :
+     EXPR3'.  If EXPR1 is true, the value of the expression is EXPR2;
+     otherwise it is EXPR3.  Only one of EXPR2 and EXPR3 is evaluated.
+
+`= += -= *= /= %= ^='
+     Assignment.  Both absolute assignment (`VAR=VALUE') and operator
+     assignment (the other forms) are supported.
+
+   *Note Expressions::.
+
+
+File: gawk.info,  Node: Control Flow Summary,  Next: I/O Summary,  Prev: Operator Summary,  Up: Actions Summary
+
+Control Statements
+------------------
+
+   The control statements are as follows:
+
+     if (CONDITION) STATEMENT [ else STATEMENT ]
+     while (CONDITION) STATEMENT
+     do STATEMENT while (CONDITION)
+     for (EXPR1; EXPR2; EXPR3) STATEMENT
+     for (VAR in ARRAY) STATEMENT
+     break
+     continue
+     delete ARRAY[INDEX]
+     delete ARRAY
+     exit [ EXPRESSION ]
+     { STATEMENTS }
+
+   *Note Control Statements in Actions: Statements.
+
+
+File: gawk.info,  Node: I/O Summary,  Next: Printf Summary,  Prev: Control Flow Summary,  Up: Actions Summary
+
+I/O Statements
+--------------
+
+   The Input/Output statements are as follows:
+
+`getline'
+     Set `$0' from next input record; set `NF', `NR', `FNR'.  *Note
+     Explicit Input with `getline': Getline.
+
+`getline <FILE'
+     Set `$0' from next record of FILE; set `NF'.
+
+`getline VAR'
+     Set VAR from next input record; set `NR', `FNR'.
+
+`getline VAR <FILE'
+     Set VAR from next record of FILE.
+
+`COMMAND | getline'
+     Run COMMAND, piping its output into `getline'; sets `$0', `NF',
+     `NR'.
+
+`COMMAND | getline `var''
+     Run COMMAND, piping its output into `getline'; sets VAR.
+
+`next'
+     Stop processing the current input record.  The next input record
+     is read and processing starts over with the first pattern in the
+     `awk' program.  If the end of the input data is reached, the `END'
+     rule(s), if any, are executed.  *Note The `next' Statement: Next
+     Statement.
+
+`nextfile'
+     Stop processing the current input file.  The next input record
+     read comes from the next input file.  `FILENAME' is updated, `FNR'
+     is set to one, `ARGIND' is incremented, and processing starts over
+     with the first pattern in the `awk' program.  If the end of the
+     input data is reached, the `END' rule(s), if any, are executed.
+     Earlier versions of `gawk' used `next file'; this usage is still
+     supported, but is considered to be deprecated.  *Note The
+     `nextfile' Statement: Nextfile Statement.
+
+`print'
+     Prints the current record.  *Note Printing Output: Printing.
+
+`print EXPR-LIST'
+     Prints expressions.
+
+`print EXPR-LIST > FILE'
+     Prints expressions to FILE. If FILE does not exist, it is created.
+     If it does exist, its contents are deleted the first time the
+     `print' is executed.
+
+`print EXPR-LIST >> FILE'
+     Prints expressions to FILE.  The previous contents of FILE are
+     retained, and the output of `print' is appended to the file.
+
+`print EXPR-LIST | COMMAND'
+     Prints expressions, sending the output down a pipe to COMMAND.
+     The pipeline to the command stays open until the `close' function
+     is called.
+
+`printf FMT, EXPR-LIST'
+     Format and print.
+
+`printf FMT, EXPR-LIST > file'
+     Format and print to FILE. If FILE does not exist, it is created.
+     If it does exist, its contents are deleted the first time the
+     `printf' is executed.
+
+`printf FMT, EXPR-LIST >> FILE'
+     Format and print to FILE.  The previous contents of FILE are
+     retained, and the output of `printf' is appended to the file.
+
+`printf FMT, EXPR-LIST | COMMAND'
+     Format and print, sending the output down a pipe to COMMAND.  The
+     pipeline to the command stays open until the `close' function is
+     called.
+
+   `getline' returns zero on end of file, and -1 on an error.  In the
+event of an error, `getline' will set `ERRNO' to the value of a
+system-dependent string that describes the error.
+
+
+File: gawk.info,  Node: Printf Summary,  Next: Special File Summary,  Prev: I/O Summary,  Up: Actions Summary
+
+`printf' Summary
+----------------
+
+   Conversion specification have the form
+`%'[FLAG][WIDTH][`.'PREC]FORMAT.  Items in brackets are optional.
+
+   The `awk' `printf' statement and `sprintf' function accept the
+following conversion specification formats:
+
+`%c'
+     An ASCII character.  If the argument used for `%c' is numeric, it
+     is treated as a character and printed.  Otherwise, the argument is
+     assumed to be a string, and the only first character of that
+     string is printed.
+
+`%d'
+`%i'
+     A decimal number (the integer part).
+
+`%e'
+`%E'
+     A floating point number of the form `[-]d.dddddde[+-]dd'.  The
+     `%E' format uses `E' instead of `e'.
+
+`%f'
+     A floating point number of the form [`-']`ddd.dddddd'.
+
+`%g'
+`%G'
+     Use either the `%e' or `%f' formats, whichever produces a shorter
+     string, with non-significant zeros suppressed.  `%G' will use `%E'
+     instead of `%e'.
+
+`%o'
+     An unsigned octal number (again, an integer).
+
+`%s'
+     A character string.
+
+`%x'
+`%X'
+     An unsigned hexadecimal number (an integer).  The `%X' format uses
+     `A' through `F' instead of `a' through `f' for decimal 10 through
+     15.
+
+`%%'
+     A single `%' character; no argument is converted.
+
+   There are optional, additional parameters that may lie between the
+`%' and the control letter:
+
+`-'
+     The expression should be left-justified within its field.
+
+`SPACE'
+     For numeric conversions, prefix positive values with a space, and
+     negative values with a minus sign.
+
+`+'
+     The plus sign, used before the width modifier (see below), says to
+     always supply a sign for numeric conversions, even if the data to
+     be formatted is positive. The `+' overrides the space modifier.
+
+`#'
+     Use an "alternate form" for certain control letters.  For `o',
+     supply a leading zero.  For `x', and `X', supply a leading `0x' or
+     `0X' for a non-zero result.  For `e', `E', and `f', the result
+     will always contain a decimal point.  For `g', and `G', trailing
+     zeros are not removed from the result.
+
+`0'
+     A leading `0' (zero) acts as a flag, that indicates output should
+     be padded with zeros instead of spaces.  This applies even to
+     non-numeric output formats.  This flag only has an effect when the
+     field width is wider than the value to be printed.
+
+`WIDTH'
+     The field should be padded to this width. The field is normally
+     padded with spaces.  If the `0' flag has been used, it is padded
+     with zeros.
+
+`.PREC'
+     A number that specifies the precision to use when printing.  For
+     the `e', `E', and `f' formats, this specifies the number of digits
+     you want printed to the right of the decimal point.  For the `g',
+     and `G' formats, it specifies the maximum number of significant
+     digits.  For the `d', `o', `i', `u', `x', and `X' formats, it
+     specifies the minimum number of digits to print.  For the `s'
+     format, it specifies the maximum number of characters from the
+     string that should be printed.
+
+   Either or both of the WIDTH and PREC values may be specified as `*'.
+In that case, the particular value is taken from the argument list.
+
+   *Note Using `printf' Statements for Fancier Printing: Printf.
+
+
+File: gawk.info,  Node: Special File Summary,  Next: Built-in Functions Summary,  Prev: Printf Summary,  Up: Actions Summary
+
+Special File Names
+------------------
+
+   When doing I/O redirection from either `print' or `printf' into a
+file, or via `getline' from a file, `gawk' recognizes certain special
+file names internally.  These file names allow access to open file
+descriptors inherited from `gawk''s parent process (usually the shell).
+The file names are:
+
+`/dev/stdin'
+     The standard input.
+
+`/dev/stdout'
+     The standard output.
+
+`/dev/stderr'
+     The standard error output.
+
+`/dev/fd/N'
+     The file denoted by the open file descriptor N.
+
+   In addition, reading the following files provides process related
+information about the running `gawk' program.  All returned records are
+terminated with a newline.
+
+`/dev/pid'
+     Returns the process ID of the current process.
+
+`/dev/ppid'
+     Returns the parent process ID of the current process.
+
+`/dev/pgrpid'
+     Returns the process group ID of the current process.
+
+`/dev/user'
+     At least four space-separated fields, containing the return values
+     of the `getuid', `geteuid', `getgid', and `getegid' system calls.
+     If there are any additional fields, they are the group IDs
+     returned by `getgroups' system call.  (Multiple groups may not be
+     supported on all systems.)
+
+These file names may also be used on the command line to name data
+files.  These file names are only recognized internally if you do not
+actually have files with these names on your system.
+
+   *Note Special File Names in `gawk': Special Files, for a longer
+description that provides the motivation for this feature.
+
+
+File: gawk.info,  Node: Built-in Functions Summary,  Next: Time Functions Summary,  Prev: Special File Summary,  Up: Actions Summary
+
+Built-in Functions
+------------------
+
+   `awk' provides a number of built-in functions for performing numeric
+operations, string related operations, and I/O related operations.
+
+   The built-in arithmetic functions are:
+
+`atan2(Y, X)'
+     the arctangent of Y/X in radians.
+
+`cos(EXPR)'
+     the cosine of EXPR, which is in radians.
+
+`exp(EXPR)'
+     the exponential function (`e ^ EXPR').
+
+`int(EXPR)'
+     truncates to integer.
+
+`log(EXPR)'
+     the natural logarithm of `expr'.
+
+`rand()'
+     a random number between zero and one.
+
+`sin(EXPR)'
+     the sine of EXPR, which is in radians.
+
+`sqrt(EXPR)'
+     the square root function.
+
+`srand([EXPR])'
+     use EXPR as a new seed for the random number generator.  If no EXPR
+     is provided, the time of day is used.  The return value is the
+     previous seed for the random number generator.
+
+   `awk' has the following built-in string functions:
+
+`gensub(REGEX, SUBST, HOW [, TARGET])'
+     If HOW is a string beginning with `g' or `G', then replace each
+     match of REGEX in TARGET with SUBST.  Otherwise, replace the
+     HOW'th occurrence. If TARGET is not supplied, use `$0'.  The
+     return value is the changed string; the original TARGET is not
+     modified. Within SUBST, `\N', where N is a digit from one to nine,
+     can be used to indicate the text that matched the N'th
+     parenthesized subexpression.  This function is `gawk'-specific.
+
+`gsub(REGEX, SUBST [, TARGET])'
+     for each substring matching the regular expression REGEX in the
+     string TARGET, substitute the string SUBST, and return the number
+     of substitutions. If TARGET is not supplied, use `$0'.
+
+`index(STR, SEARCH)'
+     returns the index of the string SEARCH in the string STR, or zero
+     if SEARCH is not present.
+
+`length([STR])'
+     returns the length of the string STR.  The length of `$0' is
+     returned if no argument is supplied.
+
+`match(STR, REGEX)'
+     returns the position in STR where the regular expression REGEX
+     occurs, or zero if REGEX is not present, and sets the values of
+     `RSTART' and `RLENGTH'.
+
+`split(STR, ARR [, REGEX])'
+     splits the string STR into the array ARR on the regular expression
+     REGEX, and returns the number of elements.  If REGEX is omitted,
+     `FS' is used instead. REGEX can be the null string, causing each
+     character to be placed into its own array element.  The array ARR
+     is cleared first.
+
+`sprintf(FMT, EXPR-LIST)'
+     prints EXPR-LIST according to FMT, and returns the resulting
+     string.
+
+`sub(REGEX, SUBST [, TARGET])'
+     just like `gsub', but only the first matching substring is
+     replaced.
+
+`substr(STR, INDEX [, LEN])'
+     returns the LEN-character substring of STR starting at INDEX.  If
+     LEN is omitted, the rest of STR is used.
+
+`tolower(STR)'
+     returns a copy of the string STR, with all the upper-case
+     characters in STR translated to their corresponding lower-case
+     counterparts.  Non-alphabetic characters are left unchanged.
+
+`toupper(STR)'
+     returns a copy of the string STR, with all the lower-case
+     characters in STR translated to their corresponding upper-case
+     counterparts.  Non-alphabetic characters are left unchanged.
+
+   The I/O related functions are:
+
+`close(EXPR)'
+     Close the open file or pipe denoted by EXPR.
+
+`fflush([EXPR])'
+     Flush any buffered output for the output file or pipe denoted by
+     EXPR.  If EXPR is omitted, standard output is flushed.  If EXPR is
+     the null string (`""'), all output buffers are flushed.
+
+`system(CMD-LINE)'
+     Execute the command CMD-LINE, and return the exit status.  If your
+     operating system does not support `system', calling it will
+     generate a fatal error.
+
+     `system("")' can be used to force `awk' to flush any pending
+     output.  This is more portable, but less obvious, than calling
+     `fflush'.
+
+
+File: gawk.info,  Node: Time Functions Summary,  Next: String Constants Summary,  Prev: Built-in Functions Summary,  Up: Actions Summary
+
+Time Functions
+--------------
+
+   The following two functions are available for getting the current
+time of day, and for formatting time stamps.  They are specific to
+`gawk'.
+
+`systime()'
+     returns the current time of day as the number of seconds since a
+     particular epoch (Midnight, January 1, 1970 UTC, on POSIX systems).
+
+`strftime([FORMAT[, TIMESTAMP]])'
+     formats TIMESTAMP according to the specification in FORMAT.  The
+     current time of day is used if no TIMESTAMP is supplied.  A
+     default format equivalent to the output of the `date' utility is
+     used if no FORMAT is supplied.  *Note Functions for Dealing with
+     Time Stamps: Time Functions, for the details on the conversion
+     specifiers that `strftime' accepts.
+
+
+File: gawk.info,  Node: String Constants Summary,  Prev: Time Functions Summary,  Up: Actions Summary
+
+String Constants
+----------------
+
+   String constants in `awk' are sequences of characters enclosed in
+double quotes (`"').  Within strings, certain "escape sequences" are
+recognized, as in C.  These are:
+
+`\\'
+     A literal backslash.
+
+`\a'
+     The "alert" character; usually the ASCII BEL character.
+
+`\b'
+     Backspace.
+
+`\f'
+     Formfeed.
+
+`\n'
+     Newline.
+
+`\r'
+     Carriage return.
+
+`\t'
+     Horizontal tab.
+
+`\v'
+     Vertical tab.
+
+`\xHEX DIGITS'
+     The character represented by the string of hexadecimal digits
+     following the `\x'.  As in ANSI C, all following hexadecimal
+     digits are considered part of the escape sequence.  E.g., `"\x1B"'
+     is a string containing the ASCII ESC (escape) character.  (The `\x'
+     escape sequence is not in POSIX `awk'.)
+
+`\DDD'
+     The character represented by the one, two, or three digit sequence
+     of octal digits.  Thus, `"\033"' is also a string containing the
+     ASCII ESC (escape) character.
+
+`\C'
+     The literal character C, if C is not one of the above.
+
+   The escape sequences may also be used inside constant regular
+expressions (e.g., the regexp `/[ \t\f\n\r\v]/' matches whitespace
+characters).
+
+   *Note Escape Sequences::.
+
+
+File: gawk.info,  Node: Functions Summary,  Next: Historical Features,  Prev: Actions Summary,  Up: Gawk Summary
+
+User-defined Functions
+======================
+
+   Functions in `awk' are defined as follows:
+
+     function NAME(PARAMETER LIST) { STATEMENTS }
+
+   Actual parameters supplied in the function call are used to
+instantiate the formal parameters declared in the function.  Arrays are
+passed by reference, other variables are passed by value.
+
+   If there are fewer arguments passed than there are names in
+PARAMETER-LIST, the extra names are given the null string as their
+value.  Extra names have the effect of local variables.
+
+   The open-parenthesis in a function call of a user-defined function
+must immediately follow the function name, without any intervening
+white space.  This is to avoid a syntactic ambiguity with the
+concatenation operator.
+
+   The word `func' may be used in place of `function' (but not in POSIX
+`awk').
+
+   Use the `return' statement to return a value from a function.
+
+   *Note User-defined Functions: User-defined.
+
+
+File: gawk.info,  Node: Historical Features,  Prev: Functions Summary,  Up: Gawk Summary
+
+Historical Features
+===================
+
+   There are two features of historical `awk' implementations that
+`gawk' supports.
+
+   First, it is possible to call the `length' built-in function not only
+with no arguments, but even without parentheses!
+
+     a = length
+
+is the same as either of
+
+     a = length()
+     a = length($0)
+
+For example:
+
+     $ echo abcdef | awk '{ print length }'
+     -| 6
+
+This feature is marked as "deprecated" in the POSIX standard, and
+`gawk' will issue a warning about its use if `--lint' is specified on
+the command line.  (The ability to use `length' this way was actually
+an accident of the original Unix `awk' implementation.  If any built-in
+function used `$0' as its default argument, it was possible to call
+that function without the parentheses.  In particular, it was common
+practice to use the `length' function in this fashion, and this usage
+was documented in the `awk' manual page.)
+
+   The other historical feature is the use of either the `break'
+statement, or the `continue' statement outside the body of a `while',
+`for', or `do' loop.  Traditional `awk' implementations have treated
+such usage as equivalent to the `next' statement.  More recent versions
+of Unix `awk' do not allow it. `gawk' supports this usage if
+`--traditional' has been specified.
+
+   *Note Command Line Options: Options, for more information about the
+`--posix' and `--lint' options.
+
+
+File: gawk.info,  Node: Installation,  Next: Notes,  Prev: Gawk Summary,  Up: Top
+
+Installing `gawk'
+*****************
+
+   This appendix provides instructions for installing `gawk' on the
+various platforms that are supported by the developers.  The primary
+developers support Unix (and one day, GNU), while the other ports were
+contributed.  The file `ACKNOWLEDGMENT' in the `gawk' distribution
+lists the electronic mail addresses of the people who did the
+respective ports, and they are also provided in *Note Reporting
+Problems and Bugs: Bugs.
+
+* Menu:
+
+* Gawk Distribution::           What is in the `gawk' distribution.
+* Unix Installation::           Installing `gawk' under various versions
+                                of Unix.
+* VMS Installation::            Installing `gawk' on VMS.
+* PC Installation::             Installing and Compiling `gawk' on MS-DOS
+                                and OS/2
+* Atari Installation::          Installing `gawk' on the Atari ST.
+* Amiga Installation::          Installing `gawk' on an Amiga.
+* Bugs::                        Reporting Problems and Bugs.
+* Other Versions::              Other freely available `awk'
+                                implementations.
+
+
+File: gawk.info,  Node: Gawk Distribution,  Next: Unix Installation,  Prev: Installation,  Up: Installation
+
+The `gawk' Distribution
+=======================
+
+   This section first describes how to get the `gawk' distribution, how
+to extract it, and then what is in the various files and subdirectories.
+
+* Menu:
+
+* Getting::                     How to get the distribution.
+* Extracting::                  How to extract the distribution.
+* Distribution contents::       What is in the distribution.
+
+
+File: gawk.info,  Node: Getting,  Next: Extracting,  Prev: Gawk Distribution,  Up: Gawk Distribution
+
+Getting the `gawk' Distribution
+-------------------------------
+
+   There are three ways you can get GNU software.
+
+  1. You can copy it from someone else who already has it.
+
+  2. You can order `gawk' directly from the Free Software Foundation.
+     Software distributions are available for Unix, MS-DOS, and VMS, on
+     tape, CD-ROM, or floppies (MS-DOS only).  The address is:
+
+          Free Software Foundation
+          59 Temple Place--Suite 330
+          Boston, MA  02111-1307 USA
+          Phone: +1-617-542-5942
+          Fax (including Japan): +1-617-542-2652
+          E-mail: `gnu@prep.ai.mit.edu'
+
+     Ordering from the FSF directly contributes to the support of the
+     foundation and to the production of more free software.
+
+  3. You can get `gawk' by using anonymous `ftp' to the Internet host
+     `ftp.gnu.ai.mit.edu', in the directory `/pub/gnu'.
+
+     Here is a list of alternate `ftp' sites from which you can obtain
+     GNU software.  When a site is listed as "SITE`:'DIRECTORY" the
+     DIRECTORY indicates the directory where GNU software is kept.  You
+     should use a site that is geographically close to you.
+
+    Asia:
+
+         `cair-archive.kaist.ac.kr:/pub/gnu'
+         `ftp.cs.titech.ac.jp'
+         `ftp.nectec.or.th:/pub/mirrors/gnu'
+         `utsun.s.u-tokyo.ac.jp:/ftpsync/prep'
+
+    Australia:
+
+         `archie.au:/gnu'
+               (`archie.oz' or `archie.oz.au' for ACSnet)
+
+    Africa:
+
+         `ftp.sun.ac.za:/pub/gnu'
+
+    Middle East:
+
+         `ftp.technion.ac.il:/pub/unsupported/gnu'
+
+    Europe:
+
+         `archive.eu.net'
+         `ftp.denet.dk'
+         `ftp.eunet.ch'
+         `ftp.funet.fi:/pub/gnu'
+         `ftp.ieunet.ie:pub/gnu'
+         `ftp.informatik.rwth-aachen.de:/pub/gnu'
+         `ftp.informatik.tu-muenchen.de'
+         `ftp.luth.se:/pub/unix/gnu'
+         `ftp.mcc.ac.uk'
+         `ftp.stacken.kth.se'
+         `ftp.sunet.se:/pub/gnu'
+         `ftp.univ-lyon1.fr:pub/gnu'
+         `ftp.win.tue.nl:/pub/gnu'
+         `irisa.irisa.fr:/pub/gnu'
+         `isy.liu.se'
+         `nic.switch.ch:/mirror/gnu'
+         `src.doc.ic.ac.uk:/gnu'
+         `unix.hensa.ac.uk:/pub/uunet/systems/gnu'
+
+    South America:
+
+         `ftp.inf.utfsm.cl:/pub/gnu'
+         `ftp.unicamp.br:/pub/gnu'
+
+    Western Canada:
+
+         `ftp.cs.ubc.ca:/mirror2/gnu'
+
+    USA:
+
+         `col.hp.com:/mirrors/gnu'
+         `f.ms.uky.edu:/pub3/gnu'
+         `ftp.cc.gatech.edu:/pub/gnu'
+         `ftp.cs.columbia.edu:/archives/gnu/prep'
+         `ftp.digex.net:/pub/gnu'
+         `ftp.hawaii.edu:/mirrors/gnu'
+         `ftp.kpc.com:/pub/mirror/gnu'
+
+    USA (continued):
+         `ftp.uu.net:/systems/gnu'
+         `gatekeeper.dec.com:/pub/GNU'
+         `jaguar.utah.edu:/gnustuff'
+         `labrea.stanford.edu'
+         `mrcnext.cso.uiuc.edu:/pub/gnu'
+         `vixen.cso.uiuc.edu:/gnu'
+         `wuarchive.wustl.edu:/systems/gnu'
+
+
+File: gawk.info,  Node: Extracting,  Next: Distribution contents,  Prev: Getting,  Up: Gawk Distribution
+
+Extracting the Distribution
+---------------------------
+
+   `gawk' is distributed as a `tar' file compressed with the GNU Zip
+program, `gzip'.
+
+   Once you have the distribution (for example, `gawk-3.0.1.tar.gz'),
+first use `gzip' to expand the file, and then use `tar' to extract it.
+You can use the following pipeline to produce the `gawk' distribution:
+
+     # Under System V, add 'o' to the tar flags
+     gzip -d -c gawk-3.0.1.tar.gz | tar -xvpf -
+
+This will create a directory named `gawk-3.0.1' in the current
+directory.
+
+   The distribution file name is of the form `gawk-V.R.N.tar.gz'.  The
+V represents the major version of `gawk', the R represents the current
+release of version V, and the N represents a "patch level", meaning
+that minor bugs have been fixed in the release.  The current patch
+level is 0, but when retrieving distributions, you should get the
+version with the highest version, release, and patch level.  (Note that
+release levels greater than or equal to 90 denote "beta," or
+non-production software; you may not wish to retrieve such a version
+unless you don't mind experimenting.)
+
+   If you are not on a Unix system, you will need to make other
+arrangements for getting and extracting the `gawk' distribution.  You
+should consult a local expert.
+
+
+File: gawk.info,  Node: Distribution contents,  Prev: Extracting,  Up: Gawk Distribution
+
+Contents of the `gawk' Distribution
+-----------------------------------
+
+   The `gawk' distribution has a number of C source files,
+documentation files, subdirectories and files related to the
+configuration process (*note Compiling and Installing `gawk' on Unix:
+Unix Installation.), and several subdirectories related to different,
+non-Unix, operating systems.
+
+various `.c', `.y', and `.h' files
+     These files are the actual `gawk' source code.
+
+`README'
+`README_d/README.*'
+     Descriptive files: `README' for `gawk' under Unix, and the rest
+     for the various hardware and software combinations.
+
+`INSTALL'
+     A file providing an overview of the configuration and installation
+     process.
+
+`PORTS'
+     A list of systems to which `gawk' has been ported, and which have
+     successfully run the test suite.
+
+`ACKNOWLEDGMENT'
+     A list of the people who contributed major parts of the code or
+     documentation.
+
+`ChangeLog'
+     A detailed list of source code changes as bugs are fixed or
+     improvements made.
+
+`NEWS'
+     A list of changes to `gawk' since the last release or patch.
+
+`COPYING'
+     The GNU General Public License.
+
+`FUTURES'
+     A brief list of features and/or changes being contemplated for
+     future releases, with some indication of the time frame for the
+     feature, based on its difficulty.
+
+`LIMITATIONS'
+     A list of those factors that limit `gawk''s performance.  Most of
+     these depend on the hardware or operating system software, and are
+     not limits in `gawk' itself.
+
+`POSIX.STD'
+     A description of one area where the POSIX standard for `awk' is
+     incorrect, and how `gawk' handles the problem.
+
+`PROBLEMS'
+     A file describing known problems with the current release.
+
+`doc/awkforai.txt'
+     A short article describing why `gawk' is a good language for AI
+     (Artificial Intelligence) programming.
+
+`doc/README.card'
+`doc/ad.block'
+`doc/awkcard.in'
+`doc/cardfonts'
+`doc/colors'
+`doc/macros'
+`doc/no.colors'
+`doc/setter.outline'
+     The `troff' source for a five-color `awk' reference card.  A
+     modern version of `troff', such as GNU Troff (`groff') is needed
+     to produce the color version. See the file `README.card' for
+     instructions if you have an older `troff'.
+
+`doc/gawk.1'
+     The `troff' source for a manual page describing `gawk'.  This is
+     distributed for the convenience of Unix users.
+
+`doc/gawk.texi'
+     The Texinfo source file for this Info file.  It should be
+     processed with TeX to produce a printed document, and with
+     `makeinfo' to produce an Info file.
+
+`doc/gawk.info'
+     The generated Info file for this Info file.
+
+`doc/igawk.1'
+     The `troff' source for a manual page describing the `igawk'
+     program presented in *Note An Easy Way to Use Library Functions:
+     Igawk Program.
+
+`doc/Makefile.in'
+     The input file used during the configuration process to generate
+     the actual `Makefile' for creating the documentation.
+
+`Makefile.in'
+`acconfig.h'
+`aclocal.m4'
+`configh.in'
+`configure.in'
+`configure'
+`custom.h'
+`missing/*'
+     These files and subdirectory are used when configuring `gawk' for
+     various Unix systems.  They are explained in detail in *Note
+     Compiling and Installing `gawk' on Unix: Unix Installation.
+
+`awklib/extract.awk'
+`awklib/Makefile.in'
+     The `awklib' directory contains a copy of `extract.awk' (*note
+     Extracting Programs from Texinfo Source Files: Extract Program.),
+     which can be used to extract the sample programs from the Texinfo
+     source file for this Info file, and a `Makefile.in' file, which
+     `configure' uses to generate a `Makefile'.  As part of the process
+     of building `gawk', the library functions from *Note A Library of
+     `awk' Functions: Library Functions, and the `igawk' program from
+     *Note An Easy Way to Use Library Functions: Igawk Program, are
+     extracted into ready to use files.  They are installed as part of
+     the installation process.
+
+`amiga/*'
+     Files needed for building `gawk' on an Amiga.  *Note Installing
+     `gawk' on an Amiga: Amiga Installation, for details.
+
+`atari/*'
+     Files needed for building `gawk' on an Atari ST.  *Note Installing
+     `gawk' on the Atari ST: Atari Installation, for details.
+
+`pc/*'
+     Files needed for building `gawk' under MS-DOS and OS/2.  *Note
+     MS-DOS and OS/2 Installation and Compilation: PC Installation, for
+     details.
+
+`vms/*'
+     Files needed for building `gawk' under VMS.  *Note How to Compile
+     and Install `gawk' on VMS: VMS Installation, for details.
+
+`test/*'
+     A test suite for `gawk'.  You can use `make check' from the top
+     level `gawk' directory to run your version of `gawk' against the
+     test suite.  If `gawk' successfully passes `make check' then you
+     can be confident of a successful port.
+
+
+File: gawk.info,  Node: Unix Installation,  Next: VMS Installation,  Prev: Gawk Distribution,  Up: Installation
+
+Compiling and Installing `gawk' on Unix
+=======================================
+
+   Usually, you can compile and install `gawk' by typing only two
+commands.  However, if you do use an unusual system, you may need to
+configure `gawk' for your system yourself.
+
+* Menu:
+
+* Quick Installation::          Compiling `gawk' under Unix.
+* Configuration Philosophy::    How it's all supposed to work.
+
+
+File: gawk.info,  Node: Quick Installation,  Next: Configuration Philosophy,  Prev: Unix Installation,  Up: Unix Installation
+
+Compiling `gawk' for Unix
+-------------------------
+
+   After you have extracted the `gawk' distribution, `cd' to
+`gawk-3.0.1'.  Like most GNU software, `gawk' is configured
+automatically for your Unix system by running the `configure' program.
+This program is a Bourne shell script that was generated automatically
+using GNU `autoconf'.  (The `autoconf' software is described fully
+starting with *Note Introduction: (autoconf)Top.)
+
+   To configure `gawk', simply run `configure':
+
+     sh ./configure
+
+   This produces a `Makefile' and `config.h' tailored to your system.
+The `config.h' file describes various facts about your system.  You may
+wish to edit the `Makefile' to change the `CFLAGS' variable, which
+controls the command line options that are passed to the C compiler
+(such as optimization levels, or compiling for debugging).
+
+   Alternatively, you can add your own values for most `make'
+variables, such as `CC' and `CFLAGS', on the command line when running
+`configure':
+
+     CC=cc CFLAGS=-g sh ./configure
+
+See the file `INSTALL' in the `gawk' distribution for all the details.
+
+   After you have run `configure', and possibly edited the `Makefile',
+type:
+
+     make
+
+and shortly thereafter, you should have an executable version of `gawk'.
+That's all there is to it!  (If these steps do not work, please send in
+a bug report; *note Reporting Problems and Bugs: Bugs..)
+
+
+File: gawk.info,  Node: Configuration Philosophy,  Prev: Quick Installation,  Up: Unix Installation
+
+The Configuration Process
+-------------------------
+
+   (This section is of interest only if you know something about using
+the C language and the Unix operating system.)
+
+   The source code for `gawk' generally attempts to adhere to formal
+standards wherever possible.  This means that `gawk' uses library
+routines that are specified by the ANSI C standard and by the POSIX
+operating system interface standard.  When using an ANSI C compiler,
+function prototypes are used to help improve the compile-time checking.
+
+   Many Unix systems do not support all of either the ANSI or the POSIX
+standards.  The `missing' subdirectory in the `gawk' distribution
+contains replacement versions of those subroutines that are most likely
+to be missing.
+
+   The `config.h' file that is created by the `configure' program
+contains definitions that describe features of the particular operating
+system where you are attempting to compile `gawk'.  The three things
+described by this file are what header files are available, so that
+they can be correctly included, what (supposedly) standard functions
+are actually available in your C libraries, and other miscellaneous
+facts about your variant of Unix.  For example, there may not be an
+`st_blksize' element in the `stat' structure.  In this case
+`HAVE_ST_BLKSIZE' would be undefined.
+
+   It is possible for your C compiler to lie to `configure'. It may do
+so by not exiting with an error when a library function is not
+available.  To get around this, you can edit the file `custom.h'.  Use
+an `#ifdef' that is appropriate for your system, and either `#define'
+any constants that `configure' should have defined but didn't, or
+`#undef' any constants that `configure' defined and should not have.
+`custom.h' is automatically included by `config.h'.
+
+   It is also possible that the `configure' program generated by
+`autoconf' will not work on your system in some other fashion.  If you
+do have a problem, the file `configure.in' is the input for `autoconf'.
+You may be able to change this file, and generate a new version of
+`configure' that will work on your system.  *Note Reporting Problems
+and Bugs: Bugs, for information on how to report problems in
+configuring `gawk'.  The same mechanism may be used to send in updates
+to `configure.in' and/or `custom.h'.
+
+
+File: gawk.info,  Node: VMS Installation,  Next: PC Installation,  Prev: Unix Installation,  Up: Installation
+
+How to Compile and Install `gawk' on VMS
+========================================
+
+   This section describes how to compile and install `gawk' under VMS.
+
+* Menu:
+
+* VMS Compilation::             How to compile `gawk' under VMS.
+* VMS Installation Details::    How to install `gawk' under VMS.
+* VMS Running::                 How to run `gawk' under VMS.
+* VMS POSIX::                   Alternate instructions for VMS POSIX.
+
+
+File: gawk.info,  Node: VMS Compilation,  Next: VMS Installation Details,  Prev: VMS Installation,  Up: VMS Installation
+
+Compiling `gawk' on VMS
+-----------------------
+
+   To compile `gawk' under VMS, there is a `DCL' command procedure that
+will issue all the necessary `CC' and `LINK' commands, and there is
+also a `Makefile' for use with the `MMS' utility.  From the source
+directory, use either
+
+     $ @[.VMS]VMSBUILD.COM
+
+or
+
+     $ MMS/DESCRIPTION=[.VMS]DESCRIP.MMS GAWK
+
+   Depending upon which C compiler you are using, follow one of the sets
+of instructions in this table:
+
+VAX C V3.x
+     Use either `vmsbuild.com' or `descrip.mms' as is.  These use
+     `CC/OPTIMIZE=NOLINE', which is essential for Version 3.0.
+
+VAX C V2.x
+     You must have Version 2.3 or 2.4; older ones won't work.  Edit
+     either `vmsbuild.com' or `descrip.mms' according to the comments
+     in them.  For `vmsbuild.com', this just entails removing two `!'
+     delimiters.  Also edit `config.h' (which is a copy of file
+     `[.config]vms-conf.h') and comment out or delete the two lines
+     `#define __STDC__ 0' and `#define VAXC_BUILTINS' near the end.
+
+GNU C
+     Edit `vmsbuild.com' or `descrip.mms'; the changes are different
+     from those for VAX C V2.x, but equally straightforward.  No
+     changes to `config.h' should be needed.
+
+DEC C
+     Edit `vmsbuild.com' or `descrip.mms' according to their comments.
+     No changes to `config.h' should be needed.
+
+   `gawk' has been tested under VAX/VMS 5.5-1 using VAX C V3.2, GNU C
+1.40 and 2.3.  It should work without modifications for VMS V4.6 and up.
+
+
+File: gawk.info,  Node: VMS Installation Details,  Next: VMS Running,  Prev: VMS Compilation,  Up: VMS Installation
+
+Installing `gawk' on VMS
+------------------------
+
+   To install `gawk', all you need is a "foreign" command, which is a
+`DCL' symbol whose value begins with a dollar sign. For example:
+
+     $ GAWK :== $disk1:[gnubin]GAWK
+
+(Substitute the actual location of `gawk.exe' for `$disk1:[gnubin]'.)
+The symbol should be placed in the `login.com' of any user who wishes
+to run `gawk', so that it will be defined every time the user logs on.
+Alternatively, the symbol may be placed in the system-wide
+`sylogin.com' procedure, which will allow all users to run `gawk'.
+
+   Optionally, the help entry can be loaded into a VMS help library:
+
+     $ LIBRARY/HELP SYS$HELP:HELPLIB [.VMS]GAWK.HLP
+
+(You may want to substitute a site-specific help library rather than
+the standard VMS library `HELPLIB'.)  After loading the help text,
+
+     $ HELP GAWK
+
+will provide information about both the `gawk' implementation and the
+`awk' programming language.
+
+   The logical name `AWK_LIBRARY' can designate a default location for
+`awk' program files.  For the `-f' option, if the specified filename
+has no device or directory path information in it, `gawk' will look in
+the current directory first, then in the directory specified by the
+translation of `AWK_LIBRARY' if the file was not found.  If after
+searching in both directories, the file still is not found, then `gawk'
+appends the suffix `.awk' to the filename and the file search will be
+re-tried.  If `AWK_LIBRARY' is not defined, that portion of the file
+search will fail benignly.
+
+
+File: gawk.info,  Node: VMS Running,  Next: VMS POSIX,  Prev: VMS Installation Details,  Up: VMS Installation
+
+Running `gawk' on VMS
+---------------------
+
+   Command line parsing and quoting conventions are significantly
+different on VMS, so examples in this Info file or from other sources
+often need minor changes.  They _are_ minor though, and all `awk'
+programs should run correctly.
+
+   Here are a couple of trivial tests:
+
+     $ gawk -- "BEGIN {print ""Hello, World!""}"
+     $ gawk -"W" version
+     ! could also be -"W version" or "-W version"
+
+Note that upper-case and mixed-case text must be quoted.
+
+   The VMS port of `gawk' includes a `DCL'-style interface in addition
+to the original shell-style interface (see the help entry for details).
+One side-effect of dual command line parsing is that if there is only a
+single parameter (as in the quoted string program above), the command
+becomes ambiguous.  To work around this, the normally optional `--'
+flag is required to force Unix style rather than `DCL' parsing.  If any
+other dash-type options (or multiple parameters such as data files to be
+processed) are present, there is no ambiguity and `--' can be omitted.
+
+   The default search path when looking for `awk' program files
+specified by the `-f' option is `"SYS$DISK:[],AWK_LIBRARY:"'.  The
+logical name `AWKPATH' can be used to override this default.  The format
+of `AWKPATH' is a comma-separated list of directory specifications.
+When defining it, the value should be quoted so that it retains a single
+translation, and not a multi-translation `RMS' searchlist.
+
+
+File: gawk.info,  Node: VMS POSIX,  Prev: VMS Running,  Up: VMS Installation
+
+Building and Using `gawk' on VMS POSIX
+--------------------------------------
+
+   Ignore the instructions above, although `vms/gawk.hlp' should still
+be made available in a help library.  The source tree should be unpacked
+into a container file subsystem rather than into the ordinary VMS file
+system.  Make sure that the two scripts, `configure' and
+`vms/posix-cc.sh', are executable; use `chmod +x' on them if necessary.
+Then execute the following two commands:
+
+     psx> CC=vms/posix-cc.sh configure
+     psx> make CC=c89 gawk
+
+The first command will construct files `config.h' and `Makefile' out of
+templates, using a script to make the C compiler fit `configure''s
+expectations.  The second command will compile and link `gawk' using
+the C compiler directly; ignore any warnings from `make' about being
+unable to redefine `CC'.  `configure' will take a very long time to
+execute, but at least it provides incremental feedback as it runs.
+
+   This has been tested with VAX/VMS V6.2, VMS POSIX V2.0, and DEC C
+V5.2.
+
+   Once built, `gawk' will work like any other shell utility.  Unlike
+the normal VMS port of `gawk', no special command line manipulation is
+needed in the VMS POSIX environment.
+
+
+File: gawk.info,  Node: PC Installation,  Next: Atari Installation,  Prev: VMS Installation,  Up: Installation
+
+MS-DOS and OS/2 Installation and Compilation
+============================================
+
+   If you have received a binary distribution prepared by the DOS
+maintainers, then `gawk' and the necessary support files will appear
+under the `gnu' directory, with executables in `gnu/bin', libraries in
+`gnu/lib/awk', and manual pages under `gnu/man'.  This is designed for
+easy installation to a `/gnu' directory on your drive, but the files
+can be installed anywhere provided `AWKPATH' is set properly.
+Regardless of the installation directory, the first line of `igawk.cmd'
+and `igawk.bat' (in `gnu/bin') may need to be edited.
+
+   The binary distribution will contain a separate file describing the
+contents. In particular, it may include more than one version of the
+`gawk' executable. OS/2 binary distributions may have a different
+arrangement, but installation is similar.
+
+   The OS/2 and MS-DOS versions of `gawk' search for program files as
+described in *Note The `AWKPATH' Environment Variable: AWKPATH Variable.
+However, semicolons (rather than colons) separate elements in the
+`AWKPATH' variable. If `AWKPATH' is not set or is empty, then the
+default search path is `".;c:/lib/awk;c:/gnu/lib/awk"'.
+
+   An `sh'-like shell (as opposed to `command.com' under MS-DOS or
+`cmd.exe' under OS/2) may be useful for `awk' programming.  Ian
+Stewartson has written an excellent shell for MS-DOS and OS/2, and a
+`ksh' clone and GNU Bash are available for OS/2. The file
+`README_d/README.pc' in the `gawk' distribution contains information on
+these shells. Users of Stewartson's shell on DOS should examine its
+documentation on handling of command-lines. In particular, the setting
+for `gawk' in the shell configuration may need to be changed, and the
+`ignoretype' option may also be of interest.
+
+   `gawk' can be compiled for MS-DOS and OS/2 using the GNU development
+tools from DJ Delorie (DJGPP, MS-DOS-only) or Eberhard Mattes (EMX,
+MS-DOS and OS/2).  Microsoft C can be used to build 16-bit versions for
+MS-DOS and OS/2.  The file `README_d/README.pc' in the `gawk'
+distribution contains additional notes, and `pc/Makefile' contains
+important notes on compilation options.
+
+   To build `gawk', copy the files in the `pc' directory (_except_ for
+`ChangeLog') to the directory with the rest of the `gawk' sources. The
+`Makefile' contains a configuration section with comments, and may need
+to be edited in order to work with your `make' utility.
+
+   The `Makefile' contains a number of targets for building various
+MS-DOS and OS/2 versions. A list of targets will be printed if the
+`make' command is given without a target. As an example, to build `gawk'
+using the DJGPP tools, enter `make djgpp'.
+
+   Using `make' to run the standard tests and to install `gawk'
+requires additional Unix-like tools, including `sh', `sed', and `cp'.
+In order to run the tests, the `test/*.ok' files may need to be
+converted so that they have the usual DOS-style end-of-line markers.
+Most of the tests will work properly with Stewartson's shell along with
+the companion utilities or appropriate GNU utilities.  However, some
+editing of `test/Makefile' is required. It is recommended that the file
+`pc/Makefile.tst' be copied to `test/Makefile' as a replacement.
+Details can be found in `README_d/README.pc'.
+
+
+File: gawk.info,  Node: Atari Installation,  Next: Amiga Installation,  Prev: PC Installation,  Up: Installation
+
+Installing `gawk' on the Atari ST
+=================================
+
+   There are no substantial differences when installing `gawk' on
+various Atari models.  Compiled `gawk' executables do not require a
+large amount of memory with most `awk' programs and should run on all
+Motorola processor based models (called further ST, even if that is not
+exactly right).
+
+   In order to use `gawk', you need to have a shell, either text or
+graphics, that does not map all the characters of a command line to
+upper-case.  Maintaining case distinction in option flags is very
+important (*note Command Line Options: Options.).  These days this is
+the default, and it may only be a problem for some very old machines.
+If your system does not preserve the case of option flags, you will
+need to upgrade your tools.  Support for I/O redirection is necessary
+to make it easy to import `awk' programs from other environments.
+Pipes are nice to have, but not vital.
+
+* Menu:
+
+* Atari Compiling::           Compiling `gawk' on Atari
+* Atari Using::               Running `gawk' on Atari
+
+
+File: gawk.info,  Node: Atari Compiling,  Next: Atari Using,  Prev: Atari Installation,  Up: Atari Installation
+
+Compiling `gawk' on the Atari ST
+--------------------------------
+
+   A proper compilation of `gawk' sources when `sizeof(int)' differs
+from `sizeof(void *)' requires an ANSI C compiler. An initial port was
+done with `gcc'.  You may actually prefer executables where `int's are
+four bytes wide, but the other variant works as well.
+
+   You may need quite a bit of memory when trying to recompile the
+`gawk' sources, as some source files (`regex.c' in particular) are quite
+big.  If you run out of memory compiling such a file, try reducing the
+optimization level for this particular file; this may help.
+
+   With a reasonable shell (Bash will do), and in particular if you run
+Linux, MiNT or a similar operating system, you have a pretty good
+chance that the `configure' utility will succeed.  Otherwise sample
+versions of `config.h' and `Makefile.st' are given in the `atari'
+subdirectory and can be edited and copied to the corresponding files in
+the main source directory.  Even if `configure' produced something, it
+might be advisable to compare its results with the sample versions and
+possibly make adjustments.
+
+   Some `gawk' source code fragments depend on a preprocessor define
+`atarist'.  This basically assumes the TOS environment with `gcc'.
+Modify these sections as appropriate if they are not right for your
+environment.  Also see the remarks about `AWKPATH' and `envsep' in
+*Note Running `gawk' on the Atari ST: Atari Using.
+
+   As shipped, the sample `config.h' claims that the `system' function
+is missing from the libraries, which is not true, and an alternative
+implementation of this function is provided in `atari/system.c'.
+Depending upon your particular combination of shell and operating
+system, you may wish to change the file to indicate that `system' is
+available.
+
+
+File: gawk.info,  Node: Atari Using,  Prev: Atari Compiling,  Up: Atari Installation
+
+Running `gawk' on the Atari ST
+------------------------------
+
+   An executable version of `gawk' should be placed, as usual, anywhere
+in your `PATH' where your shell can find it.
+
+   While executing, `gawk' creates a number of temporary files.  When
+using `gcc' libraries for TOS, `gawk' looks for either of the
+environment variables `TEMP' or `TMPDIR', in that order.  If either one
+is found, its value is assumed to be a directory for temporary files.
+This directory must exist, and if you can spare the memory, it is a
+good idea to put it on a RAM drive.  If neither `TEMP' nor `TMPDIR' are
+found, then `gawk' uses the current directory for its temporary files.
+
+   The ST version of `gawk' searches for its program files as described
+in *Note The `AWKPATH' Environment Variable: AWKPATH Variable.  The
+default value for the `AWKPATH' variable is taken from `DEFPATH'
+defined in `Makefile'. The sample `gcc'/TOS `Makefile' for the ST in
+the distribution sets `DEFPATH' to `".,c:\lib\awk,c:\gnu\lib\awk"'.
+The search path can be modified by explicitly setting `AWKPATH' to
+whatever you wish.  Note that colons cannot be used on the ST to
+separate elements in the `AWKPATH' variable, since they have another,
+reserved, meaning.  Instead, you must use a comma to separate elements
+in the path.  When recompiling, the separating character can be
+modified by initializing the `envsep' variable in `atari/gawkmisc.atr'
+to another value.
+
+   Although `awk' allows great flexibility in doing I/O redirections
+from within a program, this facility should be used with care on the ST
+running under TOS.  In some circumstances the OS routines for file
+handle pool processing lose track of certain events, causing the
+computer to crash, and requiring a reboot.  Often a warm reboot is
+sufficient.  Fortunately, this happens infrequently, and in rather
+esoteric situations.  In particular, avoid having one part of an `awk'
+program using `print' statements explicitly redirected to
+`"/dev/stdout"', while other `print' statements use the default
+standard output, and a calling shell has redirected standard output to
+a file.
+
+   When `gawk' is compiled with the ST version of `gcc' and its usual
+libraries, it will accept both `/' and `\' as path separators.  While
+this is convenient, it should be remembered that this removes one,
+technically valid, character (`/') from your file names, and that it
+may create problems for external programs, called via the `system'
+function, which may not support this convention.  Whenever it is
+possible that a file created by `gawk' will be used by some other
+program, use only backslashes.  Also remember that in `awk',
+backslashes in strings have to be doubled in order to get literal
+backslashes (*note Escape Sequences::).
+
+
+File: gawk.info,  Node: Amiga Installation,  Next: Bugs,  Prev: Atari Installation,  Up: Installation
+
+Installing `gawk' on an Amiga
+=============================
+
+   You can install `gawk' on an Amiga system using a Unix emulation
+environment available via anonymous `ftp' from `wuarchive.wustl.edu' in
+the directory `pub/aminet/dev/gcc'.  This includes a shell based on
+`pdksh'.  The primary component of this environment is a Unix emulation
+library, `ixemul.lib'.
+
+   A more complete distribution for the Amiga is available on the
+FreshFish CD-ROM from:
+
+     CRONUS
+     1840 E. Warner Road #105-265
+     Tempe, AZ 85284  USA
+     US Toll Free: (800) 804-0833
+     Phone: +1-602-491-0442
+     FAX: +1-602-491-0048
+     Email:  `info@ninemoons.com'
+     WWW: `http://www.ninemoons.com'
+     Anonymous `ftp' site: `ftp.ninemoons.com'
+
+   Once you have the distribution, you can configure `gawk' simply by
+running `configure':
+
+     configure -v m68k-cbm-amigados
+
+   Then run `make', and you should be all set!  (If these steps do not
+work, please send in a bug report; *note Reporting Problems and Bugs:
+Bugs..)
+
+
+File: gawk.info,  Node: Bugs,  Next: Other Versions,  Prev: Amiga Installation,  Up: Installation
+
+Reporting Problems and Bugs
+===========================
+
+   If you have problems with `gawk' or think that you have found a bug,
+please report it to the developers; we cannot promise to do anything
+but we might well want to fix it.
+
+   Before reporting a bug, make sure you have actually found a real bug.
+Carefully reread the documentation and see if it really says you can do
+what you're trying to do.  If it's not clear whether you should be able
+to do something or not, report that too; it's a bug in the
+documentation!
+
+   Before reporting a bug or trying to fix it yourself, try to isolate
+it to the smallest possible `awk' program and input data file that
+reproduces the problem.  Then send us the program and data file, some
+idea of what kind of Unix system you're using, and the exact results
+`gawk' gave you.  Also say what you expected to occur; this will help
+us decide whether the problem was really in the documentation.
+
+   Once you have a precise problem, there are two e-mail addresses you
+can send mail to.
+
+Internet:
+     `bug-gnu-utils@prep.ai.mit.edu'
+
+UUCP:
+     `uunet!prep.ai.mit.edu!bug-gnu-utils'
+
+   Please include the version number of `gawk' you are using.  You can
+get this information with the command `gawk --version'.  You should
+send a carbon copy of your mail to Arnold Robbins, who can be reached
+at `arnold@gnu.ai.mit.edu'.
+
+   *Important!* Do _not_ try to report bugs in `gawk' by posting to the
+Usenet/Internet newsgroup `comp.lang.awk'.  While the `gawk' developers
+do occasionally read this newsgroup, there is no guarantee that we will
+see your posting.  The steps described above are the official,
+recognized ways for reporting bugs.
+
+   Non-bug suggestions are always welcome as well.  If you have
+questions about things that are unclear in the documentation or are
+just obscure features, ask Arnold Robbins; he will try to help you out,
+although he may not have the time to fix the problem.  You can send him
+electronic mail at the Internet address above.
+
+   If you find bugs in one of the non-Unix ports of `gawk', please send
+an electronic mail message to the person who maintains that port.  They
+are listed below, and also in the `README' file in the `gawk'
+distribution.  Information in the `README' file should be considered
+authoritative if it conflicts with this Info file.
+
+   The people maintaining the non-Unix ports of `gawk' are:
+
+MS-DOS
+     Scott Deifik, `scottd@amgen.com', and Darrel Hankerson,
+     `hankedr@mail.auburn.edu'.
+
+OS/2
+     Kai Uwe Rommel, `rommel@ars.de'.
+
+VMS
+     Pat Rankin, `rankin@eql.caltech.edu'.
+
+Atari ST
+     Michal Jaegermann, `michal@gortel.phys.ualberta.ca'.
+
+Amiga
+     Fred Fish, `fnf@ninemoons.com'.
+
+   If your bug is also reproducible under Unix, please send copies of
+your report to the general GNU bug list, as well as to Arnold Robbins,
+at the addresses listed above.
+
+
+File: gawk.info,  Node: Other Versions,  Prev: Bugs,  Up: Installation
+
+Other Freely Available `awk' Implementations
+============================================
+
+     It's kind of fun to put comments like this in your awk code.
+           `// Do C++ comments work? answer: yes! of course'
+     Michael Brennan
+
+   There are two other freely available `awk' implementations.  This
+section briefly describes where to get them.
+
+Unix `awk'
+     Brian Kernighan has been able to make his implementation of `awk'
+     freely available.  You can get it via anonymous `ftp' to the host
+     `netlib.att.com'.  Change directory to `/netlib/research'. Use
+     "binary" or "image" mode, and retrieve `awk.bundle.Z'.
+
+     This is a shell archive that has been compressed with the
+     `compress' utility. It can be uncompressed with either
+     `uncompress' or the GNU `gunzip' utility.
+
+     This version requires an ANSI C compiler; GCC (the GNU C compiler)
+     works quite nicely.
+
+`mawk'
+     Michael Brennan has written an independent implementation of `awk',
+     called `mawk'.  It is available under the GPL (*note GNU GENERAL
+     PUBLIC LICENSE: Copying.), just as `gawk' is.
+
+     You can get it via anonymous `ftp' to the host `ftp.whidbey.net'.
+     Change directory to `/pub/brennan'.  Use "binary" or "image" mode,
+     and retrieve `mawk1.3.3.tar.gz' (or the latest version that is
+     there).
+
+     `gunzip' may be used to decompress this file. Installation is
+     similar to `gawk''s (*note Compiling and Installing `gawk' on
+     Unix: Unix Installation.).
+
+
+File: gawk.info,  Node: Notes,  Next: Glossary,  Prev: Installation,  Up: Top
+
+Implementation Notes
+********************
+
+   This appendix contains information mainly of interest to
+implementors and maintainers of `gawk'.  Everything in it applies
+specifically to `gawk', and not to other implementations.
+
+* Menu:
+
+* Compatibility Mode::          How to disable certain `gawk' extensions.
+* Additions::                   Making Additions To `gawk'.
+* Future Extensions::           New features that may be implemented one day.
+* Improvements::                Suggestions for improvements by volunteers.
+
+
+File: gawk.info,  Node: Compatibility Mode,  Next: Additions,  Prev: Notes,  Up: Notes
+
+Downward Compatibility and Debugging
+====================================
+
+   *Note Extensions in `gawk' Not in POSIX `awk': POSIX/GNU, for a
+summary of the GNU extensions to the `awk' language and program.  All
+of these features can be turned off by invoking `gawk' with the
+`--traditional' option, or with the `--posix' option.
+
+   If `gawk' is compiled for debugging with `-DDEBUG', then there is
+one more option available on the command line:
+
+`-W parsedebug'
+`--parsedebug'
+     Print out the parse stack information as the program is being
+     parsed.
+
+   This option is intended only for serious `gawk' developers, and not
+for the casual user.  It probably has not even been compiled into your
+version of `gawk', since it slows down execution.
+
+
+File: gawk.info,  Node: Additions,  Next: Future Extensions,  Prev: Compatibility Mode,  Up: Notes
+
+Making Additions to `gawk'
+==========================
+
+   If you should find that you wish to enhance `gawk' in a significant
+fashion, you are perfectly free to do so.  That is the point of having
+free software; the source code is available, and you are free to change
+it as you wish (*note GNU GENERAL PUBLIC LICENSE: Copying.).
+
+   This section discusses the ways you might wish to change `gawk', and
+any considerations you should bear in mind.
+
+* Menu:
+
+* Adding Code::             Adding code to the main body of `gawk'.
+* New Ports::               Porting `gawk' to a new operating system.
+
+
+File: gawk.info,  Node: Adding Code,  Next: New Ports,  Prev: Additions,  Up: Additions
+
+Adding New Features
+-------------------
+
+   You are free to add any new features you like to `gawk'.  However,
+if you want your changes to be incorporated into the `gawk'
+distribution, there are several steps that you need to take in order to
+make it possible for me to include to your changes.
+
+  1. Get the latest version.  It is much easier for me to integrate
+     changes if they are relative to the most recent distributed
+     version of `gawk'.  If your version of `gawk' is very old, I may
+     not be able to integrate them at all.  *Note Getting the `gawk'
+     Distribution: Getting, for information on getting the latest
+     version of `gawk'.
+
+  2. See *note (Version)Top:: standards, GNU Coding Standards.  This
+     document describes how GNU software should be written. If you
+     haven't read it, please do so, preferably _before_ starting to
+     modify `gawk'.  (The `GNU Coding Standards' are available as part
+     of the Autoconf distribution, from the FSF.)
+
+  3. Use the `gawk' coding style.  The C code for `gawk' follows the
+     instructions in the `GNU Coding Standards', with minor exceptions.
+     The code is formatted using the traditional "K&R" style,
+     particularly as regards the placement of braces and the use of
+     tabs.  In brief, the coding rules for `gawk' are:
+
+        * Use old style (non-prototype) function headers when defining
+          functions.
+
+        * Put the name of the function at the beginning of its own line.
+
+        * Put the return type of the function, even if it is `int', on
+          the line above the line with the name and arguments of the
+          function.
+
+        * The declarations for the function arguments should not be
+          indented.
+
+        * Put spaces around parentheses used in control structures
+          (`if', `while', `for', `do', `switch' and `return').
+
+        * Do not put spaces in front of parentheses used in function
+          calls.
+
+        * Put spaces around all C operators, and after commas in
+          function calls.
+
+        * Do not use the comma operator to produce multiple
+          side-effects, except in `for' loop initialization and
+          increment parts, and in macro bodies.
+
+        * Use real tabs for indenting, not spaces.
+
+        * Use the "K&R" brace layout style.
+
+        * Use comparisons against `NULL' and `'\0'' in the conditions of
+          `if', `while' and `for' statements, and in the `case's of
+          `switch' statements, instead of just the plain pointer or
+          character value.
+
+        * Use the `TRUE', `FALSE', and `NULL' symbolic constants, and
+          the character constant `'\0'' where appropriate, instead of
+          `1' and `0'.
+
+        * Provide one-line descriptive comments for each function.
+
+        * Do not use `#elif'. Many older Unix C compilers cannot handle
+          it.
+
+        * Do not use the `alloca' function for allocating memory off
+          the stack.  Its use causes more portability trouble than the
+          minor benefit of not having to free the storage. Instead, use
+          `malloc' and `free'.
+
+     If I have to reformat your code to follow the coding style used in
+     `gawk', I may not bother.
+
+  4. Be prepared to sign the appropriate paperwork.  In order for the
+     FSF to distribute your changes, you must either place those
+     changes in the public domain, and submit a signed statement to that
+     effect, or assign the copyright in your changes to the FSF.  Both
+     of these actions are easy to do, and _many_ people have done so
+     already. If you have questions, please contact me (*note Reporting
+     Problems and Bugs: Bugs.), or `gnu@prep.ai.mit.edu'.
+
+  5. Update the documentation.  Along with your new code, please supply
+     new sections and or chapters for this Info file.  If at all
+     possible, please use real Texinfo, instead of just supplying
+     unformatted ASCII text (although even that is better than no
+     documentation at all).  Conventions to be followed in `The GNU Awk
+     User's Guide' are provided after the `@bye' at the end of the
+     Texinfo source file.  If possible, please update the man page as
+     well.
+
+     You will also have to sign paperwork for your documentation
+     changes.
+
+  6. Submit changes as context diffs or unified diffs.  Use `diff -c -r
+     -N' or `diff -u -r -N' to compare the original `gawk' source tree
+     with your version.  (I find context diffs to be more readable, but
+     unified diffs are more compact.)  I recommend using the GNU
+     version of `diff'.  Send the output produced by either run of
+     `diff' to me when you submit your changes.  *Note Reporting
+     Problems and Bugs: Bugs, for the electronic mail information.
+
+     Using this format makes it easy for me to apply your changes to the
+     master version of the `gawk' source code (using `patch').  If I
+     have to apply the changes manually, using a text editor, I may not
+     do so, particularly if there are lots of changes.
+
+   Although this sounds like a lot of work, please remember that while
+you may write the new code, I have to maintain it and support it, and
+if it isn't possible for me to do that with a minimum of extra work,
+then I probably will not.
+
+
+File: gawk.info,  Node: New Ports,  Prev: Adding Code,  Up: Additions
+
+Porting `gawk' to a New Operating System
+----------------------------------------
+
+   If you wish to port `gawk' to a new operating system, there are
+several steps to follow.
+
+  1. Follow the guidelines in *Note Adding New Features: Adding Code,
+     concerning coding style, submission of diffs, and so on.
+
+  2. When doing a port, bear in mind that your code must co-exist
+     peacefully with the rest of `gawk', and the other ports. Avoid
+     gratuitous changes to the system-independent parts of the code. If
+     at all possible, avoid sprinkling `#ifdef's just for your port
+     throughout the code.
+
+     If the changes needed for a particular system affect too much of
+     the code, I probably will not accept them.  In such a case, you
+     will, of course, be able to distribute your changes on your own,
+     as long as you comply with the GPL (*note GNU GENERAL PUBLIC
+     LICENSE: Copying.).
+
+  3. A number of the files that come with `gawk' are maintained by other
+     people at the Free Software Foundation.  Thus, you should not
+     change them unless it is for a very good reason. I.e. changes are
+     not out of the question, but changes to these files will be
+     scrutinized extra carefully.  The files are `alloca.c',
+     `getopt.h', `getopt.c', `getopt1.c', `regex.h', `regex.c', `dfa.h',
+     `dfa.c', `install-sh', and `mkinstalldirs'.
+
+  4. Be willing to continue to maintain the port.  Non-Unix operating
+     systems are supported by volunteers who maintain the code needed
+     to compile and run `gawk' on their systems. If no-one volunteers
+     to maintain a port, that port becomes unsupported, and it may be
+     necessary to remove it from the distribution.
+
+  5. Supply an appropriate `gawkmisc.???' file.  Each port has its own
+     `gawkmisc.???' that implements certain operating system specific
+     functions. This is cleaner than a plethora of `#ifdef's scattered
+     throughout the code.  The `gawkmisc.c' in the main source
+     directory includes the appropriate `gawkmisc.???' file from each
+     subdirectory.  Be sure to update it as well.
+
+     Each port's `gawkmisc.???' file has a suffix reminiscent of the
+     machine or operating system for the port. For example,
+     `pc/gawkmisc.pc' and `vms/gawkmisc.vms'. The use of separate
+     suffixes, instead of plain `gawkmisc.c', makes it possible to move
+     files from a port's subdirectory into the main subdirectory,
+     without accidentally destroying the real `gawkmisc.c' file.
+     (Currently, this is only an issue for the MS-DOS and OS/2 ports.)
+
+  6. Supply a `Makefile' and any other C source and header files that
+     are necessary for your operating system.  All your code should be
+     in a separate subdirectory, with a name that is the same as, or
+     reminiscent of, either your operating system or the computer
+     system.  If possible, try to structure things so that it is not
+     necessary to move files out of the subdirectory into the main
+     source directory.  If that is not possible, then be sure to avoid
+     using names for your files that duplicate the names of files in
+     the main source directory.
+
+  7. Update the documentation.  Please write a section (or sections)
+     for this Info file describing the installation and compilation
+     steps needed to install and/or compile `gawk' for your system.
+
+  8. Be prepared to sign the appropriate paperwork.  In order for the
+     FSF to distribute your code, you must either place your code in
+     the public domain, and submit a signed statement to that effect,
+     or assign the copyright in your code to the FSF.  Both of these
+     actions are easy to do, and _many_ people have done so already. If
+     you have questions, please contact me, or `gnu@prep.ai.mit.edu'.
+
+   Following these steps will make it much easier to integrate your
+changes into `gawk', and have them co-exist happily with the code for
+other operating systems that is already there.
+
+   In the code that you supply, and that you maintain, feel free to use
+a coding style and brace layout that suits your taste.
+
+
+File: gawk.info,  Node: Future Extensions,  Next: Improvements,  Prev: Additions,  Up: Notes
+
+Probable Future Extensions
+==========================
+
+     AWK is a language similar to PERL, only considerably more elegant.
+     Arnold Robbins
+     
+     Hey!
+     Larry Wall
+
+   This section briefly lists extensions and possible improvements that
+indicate the directions we are currently considering for `gawk'.  The
+file `FUTURES' in the `gawk' distributions lists these extensions as
+well.
+
+   This is a list of probable future changes that will be usable by the
+`awk' language programmer.
+
+Localization
+     The GNU project is starting to support multiple languages.  It
+     will at least be possible to make `gawk' print its warnings and
+     error messages in languages other than English.  It may be
+     possible for `awk' programs to also use the multiple language
+     facilities, separate from `gawk' itself.
+
+Databases
+     It may be possible to map a GDBM/NDBM/SDBM file into an `awk'
+     array.
+
+A `PROCINFO' Array
+     The special files that provide process-related information (*note
+     Special File Names in `gawk': Special Files.)  may be superseded
+     by a `PROCINFO' array that would provide the same information, in
+     an easier to access fashion.
+
+More `lint' warnings
+     There are more things that could be checked for portability.
+
+Control of subprocess environment
+     Changes made in `gawk' to the array `ENVIRON' may be propagated to
+     subprocesses run by `gawk'.
+
+   This is a list of probable improvements that will make `gawk'
+perform better.
+
+An Improved Version of `dfa'
+     The `dfa' pattern matcher from GNU `grep' has some problems.
+     Either a new version or a fixed one will deal with some important
+     regexp matching issues.
+
+Use of GNU `malloc'
+     The GNU version of `malloc' could potentially speed up `gawk',
+     since it relies heavily on the use of dynamic memory allocation.
+
+Use of the `rx' regexp library
+     The `rx' regular expression library could potentially speed up all
+     regexp operations that require knowing the exact location of
+     matches.  This includes record termination, field and array
+     splitting, and the `sub', `gsub', `gensub' and `match' functions.
+
+
+File: gawk.info,  Node: Improvements,  Prev: Future Extensions,  Up: Notes
+
+Suggestions for Improvements
+============================
+
+   Here are some projects that would-be `gawk' hackers might like to
+take on.  They vary in size from a few days to a few weeks of
+programming, depending on which one you choose and how fast a
+programmer you are.  Please send any improvements you write to the
+maintainers at the GNU project.  *Note Adding New Features: Adding Code,
+for guidelines to follow when adding new features to `gawk'.  *Note
+Reporting Problems and Bugs: Bugs, for information on contacting the
+maintainers.
+
+  1. Compilation of `awk' programs: `gawk' uses a Bison (YACC-like)
+     parser to convert the script given it into a syntax tree; the
+     syntax tree is then executed by a simple recursive evaluator.
+     This method incurs a lot of overhead, since the recursive
+     evaluator performs many procedure calls to do even the simplest
+     things.
+
+     It should be possible for `gawk' to convert the script's parse tree
+     into a C program which the user would then compile, using the
+     normal C compiler and a special `gawk' library to provide all the
+     needed functions (regexps, fields, associative arrays, type
+     coercion, and so on).
+
+     An easier possibility might be for an intermediate phase of `awk'
+     to convert the parse tree into a linear byte code form like the
+     one used in GNU Emacs Lisp.  The recursive evaluator would then be
+     replaced by a straight line byte code interpreter that would be
+     intermediate in speed between running a compiled program and doing
+     what `gawk' does now.
+
+  2. The programs in the test suite could use documenting in this
+     Info file.
+
+  3. See the `FUTURES' file for more ideas.  Contact us if you would
+     seriously like to tackle any of the items listed there.
+
+
+File: gawk.info,  Node: Glossary,  Next: Copying,  Prev: Notes,  Up: Top
+
+Glossary
+********
+
+Action
+     A series of `awk' statements attached to a rule.  If the rule's
+     pattern matches an input record, `awk' executes the rule's action.
+     Actions are always enclosed in curly braces.  *Note Overview of
+     Actions: Action Overview.
+
+Amazing `awk' Assembler
+     Henry Spencer at the University of Toronto wrote a retargetable
+     assembler completely as `awk' scripts.  It is thousands of lines
+     long, including machine descriptions for several eight-bit
+     microcomputers.  It is a good example of a program that would have
+     been better written in another language.
+
+Amazingly Workable Formatter (`awf')
+     Henry Spencer at the University of Toronto wrote a formatter that
+     accepts a large subset of the `nroff -ms' and `nroff -man'
+     formatting commands, using `awk' and `sh'.
+
+ANSI
+     The American National Standards Institute.  This organization
+     produces many standards, among them the standards for the C and
+     C++ programming languages.
+
+Assignment
+     An `awk' expression that changes the value of some `awk' variable
+     or data object.  An object that you can assign to is called an
+     "lvalue".  The assigned values are called "rvalues".  *Note
+     Assignment Expressions: Assignment Ops.
+
+`awk' Language
+     The language in which `awk' programs are written.
+
+`awk' Program
+     An `awk' program consists of a series of "patterns" and "actions",
+     collectively known as "rules".  For each input record given to the
+     program, the program's rules are all processed in turn.  `awk'
+     programs may also contain function definitions.
+
+`awk' Script
+     Another name for an `awk' program.
+
+Bash
+     The GNU version of the standard shell (the Bourne-Again shell).
+     See "Bourne Shell."
+
+BBS
+     See "Bulletin Board System."
+
+Boolean Expression
+     Named after the English mathematician Boole. See "Logical
+     Expression."
+
+Bourne Shell
+     The standard shell (`/bin/sh') on Unix and Unix-like systems,
+     originally written by Steven R. Bourne.  Many shells (Bash, `ksh',
+     `pdksh', `zsh') are generally upwardly compatible with the Bourne
+     shell.
+
+Built-in Function
+     The `awk' language provides built-in functions that perform various
+     numerical, time stamp related, and string computations.  Examples
+     are `sqrt' (for the square root of a number) and `substr' (for a
+     substring of a string).  *Note Built-in Functions: Built-in.
+
+Built-in Variable
+     `ARGC', `ARGIND', `ARGV', `CONVFMT', `ENVIRON', `ERRNO',
+     `FIELDWIDTHS', `FILENAME', `FNR', `FS', `IGNORECASE', `NF', `NR',
+     `OFMT', `OFS', `ORS', `RLENGTH', `RSTART', `RS', `RT', and
+     `SUBSEP', are the variables that have special meaning to `awk'.
+     Changing some of them affects `awk''s running environment.
+     Several of these variables are specific to `gawk'.  *Note Built-in
+     Variables::.
+
+Braces
+     See "Curly Braces."
+
+Bulletin Board System
+     A computer system allowing users to log in and read and/or leave
+     messages for other users of the system, much like leaving paper
+     notes on a bulletin board.
+
+C
+     The system programming language that most GNU software is written
+     in.  The `awk' programming language has C-like syntax, and this
+     Info file points out similarities between `awk' and C when
+     appropriate.
+
+Character Set
+     The set of numeric codes used by a computer system to represent the
+     characters (letters, numbers, punctuation, etc.) of a particular
+     country or place. The most common character set in use today is
+     ASCII (American Standard Code for Information Interchange).  Many
+     European countries use an extension of ASCII known as ISO-8859-1
+     (ISO Latin-1).
+
+CHEM
+     A preprocessor for `pic' that reads descriptions of molecules and
+     produces `pic' input for drawing them.  It was written in `awk' by
+     Brian Kernighan and Jon Bentley, and is available from
+     `netlib@research.att.com'.
+
+Compound Statement
+     A series of `awk' statements, enclosed in curly braces.  Compound
+     statements may be nested.  *Note Control Statements in Actions:
+     Statements.
+
+Concatenation
+     Concatenating two strings means sticking them together, one after
+     another, giving a new string.  For example, the string `foo'
+     concatenated with the string `bar' gives the string `foobar'.
+     *Note String Concatenation: Concatenation.
+
+Conditional Expression
+     An expression using the `?:' ternary operator, such as `EXPR1 ?
+     EXPR2 : EXPR3'.  The expression EXPR1 is evaluated; if the result
+     is true, the value of the whole expression is the value of EXPR2,
+     otherwise the value is EXPR3.  In either case, only one of EXPR2
+     and EXPR3 is evaluated.  *Note Conditional Expressions:
+     Conditional Exp.
+
+Comparison Expression
+     A relation that is either true or false, such as `(a < b)'.
+     Comparison expressions are used in `if', `while', `do', and `for'
+     statements, and in patterns to select which input records to
+     process.  *Note Variable Typing and Comparison Expressions: Typing
+     and Comparison.
+
+Curly Braces
+     The characters `{' and `}'.  Curly braces are used in `awk' for
+     delimiting actions, compound statements, and function bodies.
+
+Dark Corner
+     An area in the language where specifications often were (or still
+     are) not clear, leading to unexpected or undesirable behavior.
+     Such areas are marked in this Info file with "(d.c.)" in the text,
+     and are indexed under the heading "dark corner."
+
+Data Objects
+     These are numbers and strings of characters.  Numbers are
+     converted into strings and vice versa, as needed.  *Note
+     Conversion of Strings and Numbers: Conversion.
+
+Double Precision
+     An internal representation of numbers that can have fractional
+     parts.  Double precision numbers keep track of more digits than do
+     single precision numbers, but operations on them are more
+     expensive.  This is the way `awk' stores numeric values.  It is
+     the C type `double'.
+
+Dynamic Regular Expression
+     A dynamic regular expression is a regular expression written as an
+     ordinary expression.  It could be a string constant, such as
+     `"foo"', but it may also be an expression whose value can vary.
+     *Note Using Dynamic Regexps: Computed Regexps.
+
+Environment
+     A collection of strings, of the form NAME`='VAL, that each program
+     has available to it. Users generally place values into the
+     environment in order to provide information to various programs.
+     Typical examples are the environment variables `HOME' and `PATH'.
+
+Empty String
+     See "Null String."
+
+Escape Sequences
+     A special sequence of characters used for describing non-printing
+     characters, such as `\n' for newline, or `\033' for the ASCII ESC
+     (escape) character.  *Note Escape Sequences::.
+
+Field
+     When `awk' reads an input record, it splits the record into pieces
+     separated by whitespace (or by a separator regexp which you can
+     change by setting the built-in variable `FS').  Such pieces are
+     called fields.  If the pieces are of fixed length, you can use the
+     built-in variable `FIELDWIDTHS' to describe their lengths.  *Note
+     Specifying How Fields are Separated: Field Separators, and also see
+     *Note Reading Fixed-width Data: Constant Size.
+
+Floating Point Number
+     Often referred to in mathematical terms as a "rational" number,
+     this is just a number that can have a fractional part.  See
+     "Double Precision" and "Single Precision."
+
+Format
+     Format strings are used to control the appearance of output in the
+     `printf' statement.  Also, data conversions from numbers to strings
+     are controlled by the format string contained in the built-in
+     variable `CONVFMT'.  *Note Format-Control Letters: Control Letters.
+
+Function
+     A specialized group of statements used to encapsulate general or
+     program-specific tasks.  `awk' has a number of built-in functions,
+     and also allows you to define your own.  *Note Built-in Functions:
+     Built-in, and *Note User-defined Functions: User-defined.
+
+FSF
+     See "Free Software Foundation."
+
+Free Software Foundation
+     A non-profit organization dedicated to the production and
+     distribution of freely distributable software.  It was founded by
+     Richard M. Stallman, the author of the original Emacs editor.  GNU
+     Emacs is the most widely used version of Emacs today.
+
+`gawk'
+     The GNU implementation of `awk'.
+
+General Public License
+     This document describes the terms under which `gawk' and its source
+     code may be distributed. (*note GNU GENERAL PUBLIC LICENSE:
+     Copying.)
+
+GNU
+     "GNU's not Unix".  An on-going project of the Free Software
+     Foundation to create a complete, freely distributable,
+     POSIX-compliant computing environment.
+
+GPL
+     See "General Public License."
+
+Hexadecimal
+     Base 16 notation, where the digits are `0'-`9' and `A'-`F', with
+     `A' representing 10, `B' representing 11, and so on up to `F' for
+     15.  Hexadecimal numbers are written in C using a leading `0x', to
+     indicate their base.  Thus, `0x12' is 18 (one times 16 plus 2).
+
+I/O
+     Abbreviation for "Input/Output," the act of moving data into and/or
+     out of a running program.
+
+Input Record
+     A single chunk of data read in by `awk'.  Usually, an `awk' input
+     record consists of one line of text.  *Note How Input is Split
+     into Records: Records.
+
+Integer
+     A whole number, i.e. a number that does not have a fractional part.
+
+Keyword
+     In the `awk' language, a keyword is a word that has special
+     meaning.  Keywords are reserved and may not be used as variable
+     names.
+
+     `gawk''s keywords are: `BEGIN', `END', `if', `else', `while',
+     `do...while', `for', `for...in', `break', `continue', `delete',
+     `next', `nextfile', `function', `func', and `exit'.
+
+Logical Expression
+     An expression using the operators for logic, AND, OR, and NOT,
+     written `&&', `||', and `!' in `awk'. Often called Boolean
+     expressions, after the mathematician who pioneered this kind of
+     mathematical logic.
+
+Lvalue
+     An expression that can appear on the left side of an assignment
+     operator.  In most languages, lvalues can be variables or array
+     elements.  In `awk', a field designator can also be used as an
+     lvalue.
+
+Null String
+     A string with no characters in it.  It is represented explicitly in
+     `awk' programs by placing two double-quote characters next to each
+     other (`""').  It can appear in input data by having two successive
+     occurrences of the field separator appear next to each other.
+
+Number
+     A numeric valued data object.  The `gawk' implementation uses
+     double precision floating point to represent numbers.  Very old
+     `awk' implementations use single precision floating point.
+
+Octal
+     Base-eight notation, where the digits are `0'-`7'.  Octal numbers
+     are written in C using a leading `0', to indicate their base.
+     Thus, `013' is 11 (one times 8 plus 3).
+
+Pattern
+     Patterns tell `awk' which input records are interesting to which
+     rules.
+
+     A pattern is an arbitrary conditional expression against which
+     input is tested.  If the condition is satisfied, the pattern is
+     said to "match" the input record.  A typical pattern might compare
+     the input record against a regular expression.  *Note Pattern
+     Elements: Pattern Overview.
+
+POSIX
+     The name for a series of standards being developed by the IEEE
+     that specify a Portable Operating System interface.  The "IX"
+     denotes the Unix heritage of these standards.  The main standard
+     of interest for `awk' users is `IEEE Standard for Information
+     Technology, Standard 1003.2-1992, Portable Operating System
+     Interface (POSIX) Part 2: Shell and Utilities'.  Informally, this
+     standard is often referred to as simply "P1003.2."
+
+Private
+     Variables and/or functions that are meant for use exclusively by
+     library functions, and not for the main `awk' program. Special
+     care must be taken when naming such variables and functions.
+     *Note Naming Library Function Global Variables: Library Names.
+
+Range (of input lines)
+     A sequence of consecutive lines from the input file.  A pattern
+     can specify ranges of input lines for `awk' to process, or it can
+     specify single lines.  *Note Pattern Elements: Pattern Overview.
+
+Recursion
+     When a function calls itself, either directly or indirectly.  If
+     this isn't clear, refer to the entry for "recursion."
+
+Redirection
+     Redirection means performing input from other than the standard
+     input stream, or output to other than the standard output stream.
+
+     You can redirect the output of the `print' and `printf' statements
+     to a file or a system command, using the `>', `>>', and `|'
+     operators.  You can redirect input to the `getline' statement using
+     the `<' and `|' operators.  *Note Redirecting Output of `print'
+     and `printf': Redirection, and *Note Explicit Input with
+     `getline': Getline.
+
+Regexp
+     Short for "regular expression".  A regexp is a pattern that
+     denotes a set of strings, possibly an infinite set.  For example,
+     the regexp `R.*xp' matches any string starting with the letter `R'
+     and ending with the letters `xp'.  In `awk', regexps are used in
+     patterns and in conditional expressions.  Regexps may contain
+     escape sequences.  *Note Regular Expressions: Regexp.
+
+Regular Expression
+     See "regexp."
+
+Regular Expression Constant
+     A regular expression constant is a regular expression written
+     within slashes, such as `/foo/'.  This regular expression is chosen
+     when you write the `awk' program, and cannot be changed doing its
+     execution.  *Note How to Use Regular Expressions: Regexp Usage.
+
+Rule
+     A segment of an `awk' program that specifies how to process single
+     input records.  A rule consists of a "pattern" and an "action".
+     `awk' reads an input record; then, for each rule, if the input
+     record satisfies the rule's pattern, `awk' executes the rule's
+     action.  Otherwise, the rule does nothing for that input record.
+
+Rvalue
+     A value that can appear on the right side of an assignment
+     operator.  In `awk', essentially every expression has a value.
+     These values are rvalues.
+
+`sed'
+     See "Stream Editor."
+
+Short-Circuit
+     The nature of the `awk' logical operators `&&' and `||'.  If the
+     value of the entire expression can be deduced from evaluating just
+     the left-hand side of these operators, the right-hand side will not
+     be evaluated (*note Boolean Expressions: Boolean Ops.).
+
+Side Effect
+     A side effect occurs when an expression has an effect aside from
+     merely producing a value.  Assignment expressions, increment and
+     decrement expressions and function calls have side effects.  *Note
+     Assignment Expressions: Assignment Ops.
+
+Single Precision
+     An internal representation of numbers that can have fractional
+     parts.  Single precision numbers keep track of fewer digits than
+     do double precision numbers, but operations on them are less
+     expensive in terms of CPU time.  This is the type used by some
+     very old versions of `awk' to store numeric values.  It is the C
+     type `float'.
+
+Space
+     The character generated by hitting the space bar on the keyboard.
+
+Special File
+     A file name interpreted internally by `gawk', instead of being
+     handed directly to the underlying operating system.  For example,
+     `/dev/stderr'.  *Note Special File Names in `gawk': Special Files.
+
+Stream Editor
+     A program that reads records from an input stream and processes
+     them one or more at a time.  This is in contrast with batch
+     programs, which may expect to read their input files in entirety
+     before starting to do anything, and with interactive programs,
+     which require input from the user.
+
+String
+     A datum consisting of a sequence of characters, such as `I am a
+     string'.  Constant strings are written with double-quotes in the
+     `awk' language, and may contain escape sequences.  *Note Escape
+     Sequences::.
+
+Tab
+     The character generated by hitting the `TAB' key on the keyboard.
+     It usually expands to up to eight spaces upon output.
+
+Unix
+     A computer operating system originally developed in the early
+     1970's at AT&T Bell Laboratories.  It initially became popular in
+     universities around the world, and later moved into commercial
+     evnironments as a software development system and network server
+     system. There are many commercial versions of Unix, as well as
+     several work-alike systems whose source code is freely available
+     (such as Linux, NetBSD, and FreeBSD).
+
+Whitespace
+     A sequence of space, tab, or newline characters occurring inside
+     an input record or a string.
+
+
+File: gawk.info,  Node: Copying,  Next: Index,  Prev: Glossary,  Up: Top
+
+GNU GENERAL PUBLIC LICENSE
+**************************
+
+                         Version 2, June 1991
+
+     Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+     59 Temple Place --- Suite 330, Boston, MA 02111-1307, USA
+     
+     Everyone is permitted to copy and distribute verbatim copies
+     of this license document, but changing it is not allowed.
+
+Preamble
+========
+
+   The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.)  You can apply it to
+your programs, too.
+
+   When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it in
+new free programs; and that you know you can do these things.
+
+   To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+   For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+   We protect your rights with two steps: (1) copyright the software,
+and (2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+   Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
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+
+   Finally, any free program is threatened constantly by software
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+
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+
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+
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+
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+  7. If, as a consequence of a court judgment or allegation of patent
+     infringement or for any other reason (not limited to patent
+     issues), conditions are imposed on you (whether by court order,
+     agreement or otherwise) that contradict the conditions of this
+     License, they do not excuse you from the conditions of this
+     License.  If you cannot distribute so as to satisfy simultaneously
+     your obligations under this License and any other pertinent
+     obligations, then as a consequence you may not distribute the
+     Program at all.  For example, if a patent license would not permit
+     royalty-free redistribution of the Program by all those who
+     receive copies directly or indirectly through you, then the only
+     way you could satisfy both it and this License would be to refrain
+     entirely from distribution of the Program.
+
+     If any portion of this section is held invalid or unenforceable
+     under any particular circumstance, the balance of the section is
+     intended to apply and the section as a whole is intended to apply
+     in other circumstances.
+
+     It is not the purpose of this section to induce you to infringe any
+     patents or other property right claims or to contest validity of
+     any such claims; this section has the sole purpose of protecting
+     the integrity of the free software distribution system, which is
+     implemented by public license practices.  Many people have made
+     generous contributions to the wide range of software distributed
+     through that system in reliance on consistent application of that
+     system; it is up to the author/donor to decide if he or she is
+     willing to distribute software through any other system and a
+     licensee cannot impose that choice.
+
+     This section is intended to make thoroughly clear what is believed
+     to be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+     certain countries either by patents or by copyrighted interfaces,
+     the original copyright holder who places the Program under this
+     License may add an explicit geographical distribution limitation
+     excluding those countries, so that distribution is permitted only
+     in or among countries not thus excluded.  In such case, this
+     License incorporates the limitation as if written in the body of
+     this License.
+
+  9. The Free Software Foundation may publish revised and/or new
+     versions of the General Public License from time to time.  Such
+     new versions will be similar in spirit to the present version, but
+     may differ in detail to address new problems or concerns.
+
+     Each version is given a distinguishing version number.  If the
+     Program specifies a version number of this License which applies
+     to it and "any later version", you have the option of following
+     the terms and conditions either of that version or of any later
+     version published by the Free Software Foundation.  If the Program
+     does not specify a version number of this License, you may choose
+     any version ever published by the Free Software Foundation.
+
+ 10. If you wish to incorporate parts of the Program into other free
+     programs whose distribution conditions are different, write to the
+     author to ask for permission.  For software which is copyrighted
+     by the Free Software Foundation, write to the Free Software
+     Foundation; we sometimes make exceptions for this.  Our decision
+     will be guided by the two goals of preserving the free status of
+     all derivatives of our free software and of promoting the sharing
+     and reuse of software generally.
+
+                                NO WARRANTY
+
+ 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
+     WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
+     LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+     HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT
+     WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT
+     NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+     FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS TO THE
+     QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+     PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
+     SERVICING, REPAIR OR CORRECTION.
+
+ 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
+     WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
+     MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
+     LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
+     INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
+     INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+     DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
+     OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY
+     OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
+     ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+
+                      END OF TERMS AND CONDITIONS
+
+How to Apply These Terms to Your New Programs
+=============================================
+
+   If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these
+terms.
+
+   To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+     ONE LINE TO GIVE THE PROGRAM'S NAME AND AN IDEA OF WHAT IT DOES.
+     Copyright (C) 19YY  NAME OF AUTHOR
+     
+     This program is free software; you can redistribute it and/or
+     modify it under the terms of the GNU General Public License
+     as published by the Free Software Foundation; either version 2
+     of the License, or (at your option) any later version.
+     
+     This program is distributed in the hope that it will be useful,
+     but WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+     GNU General Public License for more details.
+     
+     You should have received a copy of the GNU General Public License
+     along with this program; if not, write to the Free Software
+     Foundation, Inc., 59 Temple Place --- Suite 330, Boston, MA 02111-1307, USA.
+
+   Also add information on how to contact you by electronic and paper
+mail.
+
+   If the program is interactive, make it output a short notice like
+this when it starts in an interactive mode:
+
+     Gnomovision version 69, Copyright (C) 19YY NAME OF AUTHOR
+     Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
+     type `show w'.  This is free software, and you are welcome
+     to redistribute it under certain conditions; type `show c'
+     for details.
+
+   The hypothetical commands `show w' and `show c' should show the
+appropriate parts of the General Public License.  Of course, the
+commands you use may be called something other than `show w' and `show
+c'; they could even be mouse-clicks or menu items--whatever suits your
+program.
+
+   You should also get your employer (if you work as a programmer) or
+your school, if any, to sign a "copyright disclaimer" for the program,
+if necessary.  Here is a sample; alter the names:
+
+     Yoyodyne, Inc., hereby disclaims all copyright
+     interest in the program `Gnomovision'
+     (which makes passes at compilers) written
+     by James Hacker.
+     
+     SIGNATURE OF TY COON, 1 April 1989
+     Ty Coon, President of Vice
+
+   This General Public License does not permit incorporating your
+program into proprietary programs.  If your program is a subroutine
+library, you may consider it more useful to permit linking proprietary
+applications with the library.  If this is what you want to do, use the
+GNU Library General Public License instead of this License.
+
+
+File: gawk.info,  Node: Index,  Prev: Copying,  Up: Top
+
+Index
+*****
+
+* Menu:
+
+* ! operator:                            Boolean Ops.
+* != operator:                           Typing and Comparison.
+* !~ operator <1>:                       Typing and Comparison.
+* !~ operator <2>:                       Regexp Constants.
+* !~ operator <3>:                       Computed Regexps.
+* !~ operator <4>:                       Case-sensitivity.
+* !~ operator:                           Regexp Usage.
+* # (comment):                           Comments.
+* #! (executable scripts):               Executable Scripts.
+* $ (field operator):                    Fields.
+* && operator:                           Boolean Ops.
+* --assign option:                       Options.
+* --compat option:                       Options.
+* --copyleft option:                     Options.
+* --copyright option:                    Options.
+* --field-separator option:              Options.
+* --file option:                         Options.
+* --help option:                         Options.
+* --lint option:                         Options.
+* --lint-old option:                     Options.
+* --posix option:                        Options.
+* --source option:                       Options.
+* --traditional option:                  Options.
+* --usage option:                        Options.
+* --version option:                      Options.
+* -f option:                             Options.
+* -F option <1>:                         Options.
+* -F option:                             Command Line Field Separator.
+* -f option:                             Long.
+* -v option:                             Options.
+* -W option:                             Options.
+* /dev/fd:                               Special Files.
+* /dev/pgrpid:                           Special Files.
+* /dev/pid:                              Special Files.
+* /dev/ppid:                             Special Files.
+* /dev/stderr:                           Special Files.
+* /dev/stdin:                            Special Files.
+* /dev/stdout:                           Special Files.
+* /dev/user <1>:                         Passwd Functions.
+* /dev/user:                             Special Files.
+* < operator:                            Typing and Comparison.
+* <= operator:                           Typing and Comparison.
+* == operator:                           Typing and Comparison.
+* > operator:                            Typing and Comparison.
+* >= operator:                           Typing and Comparison.
+* \' regexp operator:                    GNU Regexp Operators.
+* \< regexp operator:                    GNU Regexp Operators.
+* \> regexp operator:                    GNU Regexp Operators.
+* \` regexp operator:                    GNU Regexp Operators.
+* \B regexp operator:                    GNU Regexp Operators.
+* \W regexp operator:                    GNU Regexp Operators.
+* \w regexp operator:                    GNU Regexp Operators.
+* \y regexp operator:                    GNU Regexp Operators.
+* _gr_init:                              Group Functions.
+* _pw_init:                              Passwd Functions.
+* _tm_addup:                             Mktime Function.
+* _tm_isleap:                            Mktime Function.
+* accessing fields:                      Fields.
+* account information <1>:               Group Functions.
+* account information:                   Passwd Functions.
+* acronym:                               History.
+* action, curly braces:                  Action Overview.
+* action, default:                       Very Simple.
+* action, definition of:                 Action Overview.
+* action, empty:                         Very Simple.
+* action, separating statements:         Action Overview.
+* adding new features:                   Adding Code.
+* addition:                              Arithmetic Ops.
+* Aho, Alfred:                           History.
+* AI programming, using gawk:            Distribution contents.
+* alarm.awk:                             Alarm Program.
+* amiga:                                 Amiga Installation.
+* anchors in regexps:                    Regexp Operators.
+* and operator:                          Boolean Ops.
+* anonymous ftp <1>:                     Other Versions.
+* anonymous ftp:                         Getting.
+* applications of awk:                   When.
+* ARGC:                                  Auto-set.
+* ARGIND <1>:                            Other Arguments.
+* ARGIND:                                Auto-set.
+* argument processing:                   Getopt Function.
+* arguments in function call:            Function Calls.
+* arguments, command line:               Invoking Gawk.
+* ARGV <1>:                              Other Arguments.
+* ARGV:                                  Auto-set.
+* arithmetic operators:                  Arithmetic Ops.
+* array assignment:                      Assigning Elements.
+* array reference:                       Reference to Elements.
+* array subscripts, uninitialized variables: Uninitialized Subscripts.
+* arrays:                                Array Intro.
+* arrays, associative:                   Array Intro.
+* arrays, definition of:                 Array Intro.
+* arrays, deleting an element:           Delete.
+* arrays, deleting entire contents:      Delete.
+* arrays, multi-dimensional subscripts:  Multi-dimensional.
+* arrays, presence of elements:          Reference to Elements.
+* arrays, sparse:                        Array Intro.
+* arrays, special for statement:         Scanning an Array.
+* arrays, the in operator:               Reference to Elements.
+* artificial intelligence, using gawk:   Distribution contents.
+* ASCII:                                 Ordinal Functions.
+* assert:                                Assert Function.
+* assert, C version:                     Assert Function.
+* assertions:                            Assert Function.
+* assignment operators:                  Assignment Ops.
+* assignment to fields:                  Changing Fields.
+* associative arrays:                    Array Intro.
+* atan2:                                 Numeric Functions.
+* atari:                                 Atari Installation.
+* automatic initialization:              More Complex.
+* awk language, POSIX version <1>:       Definition Syntax.
+* awk language, POSIX version <2>:       String Functions.
+* awk language, POSIX version <3>:       User-modified.
+* awk language, POSIX version <4>:       Next Statement.
+* awk language, POSIX version <5>:       Continue Statement.
+* awk language, POSIX version <6>:       Break Statement.
+* awk language, POSIX version <7>:       Precedence.
+* awk language, POSIX version <8>:       Assignment Ops.
+* awk language, POSIX version <9>:       Arithmetic Ops.
+* awk language, POSIX version <10>:      Conversion.
+* awk language, POSIX version <11>:      Format Modifiers.
+* awk language, POSIX version <12>:      OFMT.
+* awk language, POSIX version <13>:      Field Splitting Summary.
+* awk language, POSIX version <14>:      Regexp Operators.
+* awk language, POSIX version:           Escape Sequences.
+* awk language, V.4 version <1>:         SVR4.
+* awk language, V.4 version:             Escape Sequences.
+* AWKPATH environment variable:          AWKPATH Variable.
+* awksed:                                Simple Sed.
+* backslash continuation <1>:            Egrep Program.
+* backslash continuation:                Statements/Lines.
+* backslash continuation and comments:   Statements/Lines.
+* backslash continuation in csh <1>:     Statements/Lines.
+* backslash continuation in csh:         More Complex.
+* basic function of awk:                 Getting Started.
+* BBS-list file:                         Sample Data Files.
+* BEGIN special pattern:                 BEGIN/END.
+* beginfile:                             Filetrans Function.
+* body of a loop:                        While Statement.
+* book, using this:                      This Manual.
+* boolean expressions:                   Boolean Ops.
+* boolean operators:                     Boolean Ops.
+* break statement:                       Break Statement.
+* break, outside of loops:               Break Statement.
+* Brennan, Michael <1>:                  Other Versions.
+* Brennan, Michael <2>:                  Simple Sed.
+* Brennan, Michael:                      Delete.
+* buffer matching operators:             GNU Regexp Operators.
+* buffering output:                      I/O Functions.
+* buffering, interactive vs. non-interactive: I/O Functions.
+* buffering, non-interactive vs. interactive: I/O Functions.
+* buffers, flushing:                     I/O Functions.
+* bugs, known in gawk:                   Known Bugs.
+* built-in functions:                    Built-in.
+* built-in variables:                    Built-in Variables.
+* built-in variables, convey information: Auto-set.
+* built-in variables, user modifiable:   User-modified.
+* call by reference:                     Function Caveats.
+* call by value:                         Function Caveats.
+* calling a function <1>:                Function Caveats.
+* calling a function:                    Function Calls.
+* case conversion:                       String Functions.
+* case sensitivity:                      Case-sensitivity.
+* changing contents of a field:          Changing Fields.
+* changing the record separator:         Records.
+* character classes:                     Regexp Operators.
+* character encodings:                   Ordinal Functions.
+* character list:                        Regexp Operators.
+* character list, complemented:          Regexp Operators.
+* character sets:                        Ordinal Functions.
+* chr:                                   Ordinal Functions.
+* close <1>:                             I/O Functions.
+* close:                                 Close Files And Pipes.
+* closing input files and pipes:         Close Files And Pipes.
+* closing output files and pipes:        Close Files And Pipes.
+* coding style used in gawk:             Adding Code.
+* collating elements:                    Regexp Operators.
+* collating symbols:                     Regexp Operators.
+* command line:                          Invoking Gawk.
+* command line formats:                  Running gawk.
+* command line, setting FS on:           Command Line Field Separator.
+* comments:                              Comments.
+* comments and backslash continuation:   Statements/Lines.
+* common mistakes <1>:                   Typing and Comparison.
+* common mistakes <2>:                   Print Examples.
+* common mistakes <3>:                   Basic Field Splitting.
+* common mistakes:                       Computed Regexps.
+* comp.lang.awk:                         Bugs.
+* comparison expressions:                Typing and Comparison.
+* comparisons, string vs. regexp:        Typing and Comparison.
+* compatibility mode <1>:                POSIX/GNU.
+* compatibility mode:                    Options.
+* complemented character list:           Regexp Operators.
+* compound statement:                    Statements.
+* computed regular expressions:          Computed Regexps.
+* concatenation:                         Concatenation.
+* conditional expression:                Conditional Exp.
+* configuring gawk:                      Configuration Philosophy.
+* constants, types of:                   Constants.
+* continuation of lines:                 Statements/Lines.
+* continue statement:                    Continue Statement.
+* continue, outside of loops:            Continue Statement.
+* control statement:                     Statements.
+* conversion of case:                    String Functions.
+* conversion of strings and numbers:     Conversion.
+* conversions, during subscripting:      Numeric Array Subscripts.
+* converting dates to timestamps:        Mktime Function.
+* CONVFMT <1>:                           Numeric Array Subscripts.
+* CONVFMT <2>:                           User-modified.
+* CONVFMT:                               Conversion.
+* cos:                                   Numeric Functions.
+* csh, backslash continuation <1>:       Statements/Lines.
+* csh, backslash continuation:           More Complex.
+* curly braces:                          Action Overview.
+* custom.h configuration file:           Configuration Philosophy.
+* cut utility:                           Cut Program.
+* cut.awk:                               Cut Program.
+* d.c., see "dark corner":               This Manual.
+* dark corner <1>:                       Other Arguments.
+* dark corner <2>:                       Invoking Gawk.
+* dark corner <3>:                       String Functions.
+* dark corner <4>:                       Uninitialized Subscripts.
+* dark corner <5>:                       Auto-set.
+* dark corner <6>:                       Exit Statement.
+* dark corner <7>:                       Continue Statement.
+* dark corner <8>:                       Break Statement.
+* dark corner <9>:                       Using BEGIN/END.
+* dark corner <10>:                      Truth Values.
+* dark corner <11>:                      Conversion.
+* dark corner <12>:                      Assignment Options.
+* dark corner <13>:                      Using Constant Regexps.
+* dark corner <14>:                      Format Modifiers.
+* dark corner <15>:                      Control Letters.
+* dark corner <16>:                      OFMT.
+* dark corner <17>:                      Getline Summary.
+* dark corner <18>:                      Plain Getline.
+* dark corner <19>:                      Multiple Line.
+* dark corner <20>:                      Field Splitting Summary.
+* dark corner <21>:                      Single Character Fields.
+* dark corner <22>:                      Records.
+* dark corner <23>:                      Escape Sequences.
+* dark corner:                           This Manual.
+* data-driven languages:                 Getting Started.
+* dates, converting to timestamps:       Mktime Function.
+* decrement operators:                   Increment Ops.
+* default action:                        Very Simple.
+* default pattern:                       Very Simple.
+* defining functions:                    Definition Syntax.
+* Deifik, Scott <1>:                     Bugs.
+* Deifik, Scott:                         Acknowledgements.
+* delete statement:                      Delete.
+* deleting elements of arrays:           Delete.
+* deleting entire arrays:                Delete.
+* deprecated features:                   Obsolete.
+* deprecated options:                    Obsolete.
+* differences between gawk and awk <1>:  AWKPATH Variable.
+* differences between gawk and awk <2>:  String Functions.
+* differences between gawk and awk <3>:  Calling Built-in.
+* differences between gawk and awk <4>:  Delete.
+* differences between gawk and awk <5>:  Nextfile Statement.
+* differences between gawk and awk <6>:  I/O And BEGIN/END.
+* differences between gawk and awk <7>:  Conditional Exp.
+* differences between gawk and awk <8>:  Arithmetic Ops.
+* differences between gawk and awk <9>:  Using Constant Regexps.
+* differences between gawk and awk <10>: Scalar Constants.
+* differences between gawk and awk <11>: Close Files And Pipes.
+* differences between gawk and awk <12>: Special Files.
+* differences between gawk and awk <13>: Redirection.
+* differences between gawk and awk <14>: Getline Summary.
+* differences between gawk and awk <15>: Getline Intro.
+* differences between gawk and awk <16>: Single Character Fields.
+* differences between gawk and awk <17>: Records.
+* differences between gawk and awk:      Case-sensitivity.
+* directory search:                      AWKPATH Variable.
+* division:                              Arithmetic Ops.
+* documenting awk programs <1>:          Library Names.
+* documenting awk programs:              Comments.
+* dupword.awk:                           Dupword Program.
+* dynamic regular expressions:           Computed Regexps.
+* EBCDIC:                                Ordinal Functions.
+* egrep <1>:                             Regexp Operators.
+* egrep:                                 One-shot.
+* egrep utility:                         Egrep Program.
+* egrep.awk:                             Egrep Program.
+* element assignment:                    Assigning Elements.
+* element of array:                      Reference to Elements.
+* empty action:                          Very Simple.
+* empty pattern:                         Empty.
+* empty program:                         Invoking Gawk.
+* empty string <1>:                      Truth Values.
+* empty string <2>:                      Conversion.
+* empty string <3>:                      Regexp Field Splitting.
+* empty string:                          Records.
+* END special pattern:                   BEGIN/END.
+* endfile:                               Filetrans Function.
+* endgrent:                              Group Functions.
+* endpwent:                              Passwd Functions.
+* ENVIRON:                               Auto-set.
+* environment variable, AWKPATH:         AWKPATH Variable.
+* environment variable, POSIXLY_CORRECT: Options.
+* equivalence classes:                   Regexp Operators.
+* ERRNO <1>:                             Auto-set.
+* ERRNO <2>:                             Close Files And Pipes.
+* ERRNO:                                 Getline Intro.
+* errors, common <1>:                    Typing and Comparison.
+* errors, common <2>:                    Print Examples.
+* errors, common <3>:                    Basic Field Splitting.
+* errors, common:                        Computed Regexps.
+* escape processing, sub et. al.:        String Functions.
+* escape sequence notation:              Escape Sequences.
+* evaluation, order of:                  Calling Built-in.
+* examining fields:                      Fields.
+* executable scripts:                    Executable Scripts.
+* exit statement:                        Exit Statement.
+* exp:                                   Numeric Functions.
+* explicit input:                        Getline.
+* exponentiation:                        Arithmetic Ops.
+* expression:                            Expressions.
+* expression, assignment:                Assignment Ops.
+* expression, boolean:                   Boolean Ops.
+* expression, comparison:                Typing and Comparison.
+* expression, conditional:               Conditional Exp.
+* expression, matching:                  Typing and Comparison.
+* extract.awk:                           Extract Program.
+* features, adding:                      Adding Code.
+* fflush:                                I/O Functions.
+* field operator $:                      Fields.
+* field separator, choice of:            Basic Field Splitting.
+* field separator, FS:                   Basic Field Splitting.
+* field separator, on command line:      Command Line Field Separator.
+* field, changing contents of:           Changing Fields.
+* fields:                                Fields.
+* fields, separating:                    Basic Field Splitting.
+* FIELDWIDTHS:                           User-modified.
+* file descriptors:                      Special Files.
+* file, awk program:                     Long.
+* FILENAME <1>:                          Auto-set.
+* FILENAME <2>:                          Getline Summary.
+* FILENAME:                              Reading Files.
+* FILENAME, being set by getline:        Getline Summary.
+* Fish, Fred:                            Bugs.
+* flushing buffers:                      I/O Functions.
+* FNR <1>:                               Auto-set.
+* FNR:                                   Records.
+* for (x in ...):                        Scanning an Array.
+* for statement:                         For Statement.
+* format specifier:                      Control Letters.
+* format string:                         Basic Printf.
+* format, numeric output:                OFMT.
+* formatted output:                      Printf.
+* formatted timestamps:                  Gettimeofday Function.
+* Free Software Foundation <1>:          Getting.
+* Free Software Foundation:              Manual History.
+* FreeBSD:                               Manual History.
+* Friedl, Jeffrey:                       Acknowledgements.
+* FS <1>:                                User-modified.
+* FS:                                    Basic Field Splitting.
+* ftp, anonymous <1>:                    Other Versions.
+* ftp, anonymous:                        Getting.
+* function call <1>:                     Function Caveats.
+* function call:                         Function Calls.
+* function definition:                   Definition Syntax.
+* function, recursive:                   Definition Syntax.
+* functions, undefined:                  Function Caveats.
+* functions, user-defined:               User-defined.
+* gawk coding style:                     Adding Code.
+* gensub:                                String Functions.
+* getgrent:                              Group Functions.
+* getgrent, C version:                   Group Functions.
+* getgrgid:                              Group Functions.
+* getgrnam:                              Group Functions.
+* getgruser:                             Group Functions.
+* getline:                               Getline.
+* getline, return values:                Getline Intro.
+* getline, setting FILENAME:             Getline Summary.
+* getopt:                                Getopt Function.
+* getopt, C version:                     Getopt Function.
+* getpwent:                              Passwd Functions.
+* getpwent, C version:                   Passwd Functions.
+* getpwnam:                              Passwd Functions.
+* getpwuid:                              Passwd Functions.
+* gettimeofday:                          Gettimeofday Function.
+* getting gawk:                          Getting.
+* GNU Project:                           Manual History.
+* grcat program:                         Group Functions.
+* grcat.c:                               Group Functions.
+* group file:                            Group Functions.
+* group information:                     Group Functions.
+* gsub:                                  String Functions.
+* gsub, third argument of:               String Functions.
+* Hankerson, Darrel <1>:                 Bugs.
+* Hankerson, Darrel:                     Acknowledgements.
+* historical features <1>:               Historical Features.
+* historical features <2>:               String Functions.
+* historical features <3>:               Continue Statement.
+* historical features <4>:               Break Statement.
+* historical features:                   Command Line Field Separator.
+* history of awk:                        History.
+* histsort.awk:                          History Sorting.
+* how awk works:                         Two Rules.
+* Hughes, Phil:                          Acknowledgements.
+* I/O from BEGIN and END:                I/O And BEGIN/END.
+* id utility:                            Id Program.
+* id.awk:                                Id Program.
+* if-else statement:                     If Statement.
+* igawk.sh:                              Igawk Program.
+* IGNORECASE <1>:                        User-modified.
+* IGNORECASE:                            Case-sensitivity.
+* ignoring case:                         Case-sensitivity.
+* implementation limits <1>:             Redirection.
+* implementation limits:                 Getline Summary.
+* in operator:                           Typing and Comparison.
+* increment operators:                   Increment Ops.
+* index:                                 String Functions.
+* initialization, automatic:             More Complex.
+* input:                                 Reading Files.
+* input file, sample:                    Sample Data Files.
+* input files, skipping:                 Nextfile Function.
+* input pipeline:                        Getline/Pipe.
+* input redirection:                     Getline/File.
+* input, explicit:                       Getline.
+* input, getline command:                Getline.
+* input, multiple line records:          Multiple Line.
+* input, standard:                       Read Terminal.
+* installation, amiga:                   Amiga Installation.
+* installation, atari:                   Atari Installation.
+* installation, MS-DOS and OS/2:         PC Installation.
+* installation, unix:                    Quick Installation.
+* installation, vms:                     VMS Installation.
+* int:                                   Numeric Functions.
+* interaction, awk and other programs:   I/O Functions.
+* interactive buffering vs. non-interactive: I/O Functions.
+* interval expressions:                  Regexp Operators.
+* inventory-shipped file:                Sample Data Files.
+* invocation of gawk:                    Invoking Gawk.
+* ISO 8601:                              Time Functions.
+* ISO 8859-1 <1>:                        Glossary.
+* ISO 8859-1:                            Case-sensitivity.
+* ISO Latin-1 <1>:                       Glossary.
+* ISO Latin-1:                           Case-sensitivity.
+* Jaegermann, Michal <1>:                Bugs.
+* Jaegermann, Michal:                    Acknowledgements.
+* join:                                  Join Function.
+* Kernighan, Brian <1>:                  Other Versions.
+* Kernighan, Brian <2>:                  BTL.
+* Kernighan, Brian <3>:                  Acknowledgements.
+* Kernighan, Brian:                      History.
+* known bugs:                            Known Bugs.
+* labels.awk:                            Labels Program.
+* language, awk:                         This Manual.
+* language, data-driven:                 Getting Started.
+* language, procedural:                  Getting Started.
+* leftmost longest match <1>:            Multiple Line.
+* leftmost longest match:                Leftmost Longest.
+* length:                                String Functions.
+* limitations <1>:                       Redirection.
+* limitations:                           Getline Summary.
+* line break:                            Statements/Lines.
+* line continuation <1>:                 Conditional Exp.
+* line continuation <2>:                 Boolean Ops.
+* line continuation <3>:                 Print Examples.
+* line continuation:                     Statements/Lines.
+* Linux <1>:                             Atari Compiling.
+* Linux:                                 Manual History.
+* locale, definition of:                 Time Functions.
+* log:                                   Numeric Functions.
+* logical false:                         Truth Values.
+* logical operations:                    Boolean Ops.
+* logical true:                          Truth Values.
+* login information:                     Passwd Functions.
+* long options:                          Invoking Gawk.
+* loop:                                  While Statement.
+* loops, exiting:                        Break Statement.
+* lvalue:                                Assignment Ops.
+* mark parity:                           Ordinal Functions.
+* match:                                 String Functions.
+* matching ranges of lines:              Ranges.
+* matching, leftmost longest <1>:        Multiple Line.
+* matching, leftmost longest:            Leftmost Longest.
+* mawk:                                  Other Versions.
+* merging strings:                       Join Function.
+* metacharacters:                        Regexp Operators.
+* mistakes, common <1>:                  Typing and Comparison.
+* mistakes, common <2>:                  Print Examples.
+* mistakes, common <3>:                  Basic Field Splitting.
+* mistakes, common:                      Computed Regexps.
+* mktime:                                Mktime Function.
+* modifiers (in format specifiers):      Format Modifiers.
+* multi-dimensional subscripts:          Multi-dimensional.
+* multiple line records:                 Multiple Line.
+* multiple passes over data:             Other Arguments.
+* multiple statements on one line:       Statements/Lines.
+* multiplication:                        Arithmetic Ops.
+* names, use of:                         Definition Syntax.
+* namespace issues in awk:               Library Names.
+* namespaces:                            Definition Syntax.
+* NetBSD:                                Manual History.
+* new awk:                               History.
+* new awk vs. old awk:                   Names.
+* newline:                               Statements/Lines.
+* next file statement:                   Nextfile Statement.
+* next statement:                        Next Statement.
+* next, inside a user-defined function:  Next Statement.
+* nextfile function:                     Nextfile Function.
+* nextfile statement:                    Nextfile Statement.
+* NF <1>:                                Auto-set.
+* NF:                                    Fields.
+* non-interactive buffering vs. interactive: I/O Functions.
+* not operator:                          Boolean Ops.
+* NR <1>:                                Auto-set.
+* NR:                                    Records.
+* null string <1>:                       Truth Values.
+* null string <2>:                       Conversion.
+* null string:                           Regexp Field Splitting.
+* null string, as array subscript:       Uninitialized Subscripts.
+* number of fields, NF:                  Fields.
+* number of records, NR, FNR:            Records.
+* numbers, used as subscripts:           Numeric Array Subscripts.
+* numeric character values:              Ordinal Functions.
+* numeric constant:                      Scalar Constants.
+* numeric output format:                 OFMT.
+* numeric string:                        Typing and Comparison.
+* numeric value:                         Scalar Constants.
+* obsolete features:                     Obsolete.
+* obsolete options:                      Obsolete.
+* OFMT <1>:                              User-modified.
+* OFMT <2>:                              Conversion.
+* OFMT:                                  OFMT.
+* OFS <1>:                               User-modified.
+* OFS:                                   Output Separators.
+* old awk:                               History.
+* old awk vs. new awk:                   Names.
+* one-liners:                            One-liners.
+* operations, logical:                   Boolean Ops.
+* operator precedence:                   Precedence.
+* operators, arithmetic:                 Arithmetic Ops.
+* operators, assignment:                 Assignment Ops.
+* operators, boolean:                    Boolean Ops.
+* operators, decrement:                  Increment Ops.
+* operators, increment:                  Increment Ops.
+* operators, regexp matching:            Regexp Usage.
+* operators, relational:                 Typing and Comparison.
+* operators, short-circuit:              Boolean Ops.
+* operators, string:                     Concatenation.
+* operators, string-matching:            Regexp Usage.
+* options, command line:                 Invoking Gawk.
+* options, long:                         Invoking Gawk.
+* or operator:                           Boolean Ops.
+* ord:                                   Ordinal Functions.
+* order of evaluation:                   Calling Built-in.
+* ORS <1>:                               User-modified.
+* ORS:                                   Output Separators.
+* output:                                Printing.
+* output field separator, OFS:           Output Separators.
+* output format specifier, OFMT:         OFMT.
+* output record separator, ORS:          Output Separators.
+* output redirection:                    Redirection.
+* output, buffering:                     I/O Functions.
+* output, formatted:                     Printf.
+* output, piping:                        Redirection.
+* passes, multiple:                      Other Arguments.
+* password file:                         Passwd Functions.
+* path, search:                          AWKPATH Variable.
+* pattern, BEGIN:                        BEGIN/END.
+* pattern, default:                      Very Simple.
+* pattern, definition of:                Patterns and Actions.
+* pattern, empty:                        Empty.
+* pattern, END:                          BEGIN/END.
+* pattern, range:                        Ranges.
+* pattern, regular expressions:          Regexp.
+* patterns, types of:                    Kinds of Patterns.
+* per file initialization and clean-up:  Filetrans Function.
+* PERL:                                  Future Extensions.
+* pipeline, input:                       Getline/Pipe.
+* pipes for output:                      Redirection.
+* portability issues <1>:                Portability Notes.
+* portability issues <2>:                Definition Syntax.
+* portability issues <3>:                I/O Functions.
+* portability issues <4>:                String Functions.
+* portability issues <5>:                Delete.
+* portability issues <6>:                Close Files And Pipes.
+* portability issues <7>:                Escape Sequences.
+* portability issues:                    Statements/Lines.
+* porting gawk:                          New Ports.
+* POSIX awk <1>:                         Definition Syntax.
+* POSIX awk <2>:                         String Functions.
+* POSIX awk <3>:                         User-modified.
+* POSIX awk <4>:                         Next Statement.
+* POSIX awk <5>:                         Continue Statement.
+* POSIX awk <6>:                         Break Statement.
+* POSIX awk <7>:                         Precedence.
+* POSIX awk <8>:                         Assignment Ops.
+* POSIX awk <9>:                         Arithmetic Ops.
+* POSIX awk <10>:                        Conversion.
+* POSIX awk <11>:                        Format Modifiers.
+* POSIX awk <12>:                        OFMT.
+* POSIX awk <13>:                        Field Splitting Summary.
+* POSIX awk <14>:                        Regexp Operators.
+* POSIX awk:                             Escape Sequences.
+* POSIX mode:                            Options.
+* POSIXLY_CORRECT environment variable:  Options.
+* precedence:                            Precedence.
+* precedence, regexp operators:          Regexp Operators.
+* print statement:                       Print.
+* printf statement, syntax of:           Basic Printf.
+* printf, format-control characters:     Control Letters.
+* printf, modifiers:                     Format Modifiers.
+* printing:                              Printing.
+* procedural languages:                  Getting Started.
+* process information:                   Special Files.
+* processing arguments:                  Getopt Function.
+* program file:                          Long.
+* program, awk:                          This Manual.
+* program, definition of:                Getting Started.
+* program, self contained:               Executable Scripts.
+* programs, documenting <1>:             Library Names.
+* programs, documenting:                 Comments.
+* pwcat program:                         Passwd Functions.
+* pwcat.c:                               Passwd Functions.
+* quotient:                              Arithmetic Ops.
+* quoting, shell <1>:                    Long.
+* quoting, shell:                        Read Terminal.
+* Rakitzis, Byron:                       History Sorting.
+* rand:                                  Numeric Functions.
+* random numbers, seed of:               Numeric Functions.
+* range pattern:                         Ranges.
+* Rankin, Pat <1>:                       Bugs.
+* Rankin, Pat <2>:                       Assignment Ops.
+* Rankin, Pat:                           Acknowledgements.
+* reading files:                         Reading Files.
+* reading files, getline command:        Getline.
+* reading files, multiple line records:  Multiple Line.
+* record separator, RS:                  Records.
+* record terminator, RT:                 Records.
+* record, definition of:                 Records.
+* records, multiple line:                Multiple Line.
+* recursive function:                    Definition Syntax.
+* redirection of input:                  Getline/File.
+* redirection of output:                 Redirection.
+* reference to array:                    Reference to Elements.
+* regexp:                                Regexp.
+* regexp as expression:                  Typing and Comparison.
+* regexp comparison vs. string comparison: Typing and Comparison.
+* regexp constant:                       Regexp Usage.
+* regexp constants, difference between slashes and quotes: Computed Regexps.
+* regexp match/non-match operators <1>:  Typing and Comparison.
+* regexp match/non-match operators:      Regexp Usage.
+* regexp matching operators:             Regexp Usage.
+* regexp operators:                      Regexp Operators.
+* regexp operators, GNU specific:        GNU Regexp Operators.
+* regexp operators, precedence of:       Regexp Operators.
+* regexp, anchors:                       Regexp Operators.
+* regexp, dynamic:                       Computed Regexps.
+* regexp, effect of command line options: GNU Regexp Operators.
+* regular expression:                    Regexp.
+* regular expression metacharacters:     Regexp Operators.
+* regular expressions as field separators: Basic Field Splitting.
+* regular expressions as patterns:       Regexp.
+* regular expressions as record separators: Records.
+* regular expressions, computed:         Computed Regexps.
+* relational operators:                  Typing and Comparison.
+* remainder:                             Arithmetic Ops.
+* removing elements of arrays:           Delete.
+* return statement:                      Return Statement.
+* RFC-1036:                              Time Functions.
+* RFC-822:                               Time Functions.
+* RLENGTH <1>:                           String Functions.
+* RLENGTH:                               Auto-set.
+* Robbins, Miriam:                       Acknowledgements.
+* Rommel, Kai Uwe <1>:                   Bugs.
+* Rommel, Kai Uwe:                       Acknowledgements.
+* round:                                 Round Function.
+* rounding:                              Round Function.
+* RS <1>:                                User-modified.
+* RS:                                    Records.
+* RSTART <1>:                            String Functions.
+* RSTART:                                Auto-set.
+* RT <1>:                                Auto-set.
+* RT <2>:                                Multiple Line.
+* RT:                                    Records.
+* rule, definition of:                   Getting Started.
+* running awk programs:                  Running gawk.
+* running long programs:                 Long.
+* rvalue:                                Assignment Ops.
+* sample input file:                     Sample Data Files.
+* scanning an array:                     Scanning an Array.
+* script, definition of:                 Getting Started.
+* scripts, executable:                   Executable Scripts.
+* scripts, shell:                        Executable Scripts.
+* search path:                           AWKPATH Variable.
+* search path, for source files:         AWKPATH Variable.
+* sed utility <1>:                       Igawk Program.
+* sed utility <2>:                       Simple Sed.
+* sed utility:                           Field Splitting Summary.
+* seed for random numbers:               Numeric Functions.
+* self contained programs:               Executable Scripts.
+* shell quoting <1>:                     Long.
+* shell quoting:                         Read Terminal.
+* shell scripts:                         Executable Scripts.
+* short-circuit operators:               Boolean Ops.
+* side effect:                           Assignment Ops.
+* simple stream editor:                  Simple Sed.
+* sin:                                   Numeric Functions.
+* single character fields:               Single Character Fields.
+* single quotes, why needed:             One-shot.
+* skipping input files:                  Nextfile Function.
+* skipping lines between markers:        Ranges.
+* sparse arrays:                         Array Intro.
+* split:                                 String Functions.
+* split utility:                         Split Program.
+* split.awk:                             Split Program.
+* sprintf:                               String Functions.
+* sqrt:                                  Numeric Functions.
+* srand:                                 Numeric Functions.
+* Stallman, Richard <1>:                 Acknowledgements.
+* Stallman, Richard:                     Manual History.
+* standard error output:                 Special Files.
+* standard input <1>:                    Special Files.
+* standard input <2>:                    Reading Files.
+* standard input:                        Read Terminal.
+* standard output:                       Special Files.
+* statement, compound:                   Statements.
+* stream editor:                         Field Splitting Summary.
+* stream editor, simple:                 Simple Sed.
+* strftime:                              Time Functions.
+* string comparison vs. regexp comparison: Typing and Comparison.
+* string constants:                      Constants.
+* string operators:                      Concatenation.
+* string-matching operators:             Regexp Usage.
+* sub:                                   String Functions.
+* sub, third argument of:                String Functions.
+* subscripts in arrays:                  Multi-dimensional.
+* SUBSEP <1>:                            Multi-dimensional.
+* SUBSEP:                                User-modified.
+* substr:                                String Functions.
+* subtraction:                           Arithmetic Ops.
+* system:                                I/O Functions.
+* systime:                               Time Functions.
+* Tcl:                                   Library Names.
+* tee utility:                           Tee Program.
+* tee.awk:                               Tee Program.
+* terminator, record:                    Records.
+* time of day:                           Time Functions.
+* timestamps:                            Time Functions.
+* timestamps, converting from dates:     Mktime Function.
+* timestamps, formatted:                 Gettimeofday Function.
+* tolower:                               String Functions.
+* toupper:                               String Functions.
+* translate.awk:                         Translate Program.
+* Trueman, David:                        Acknowledgements.
+* truth values:                          Truth Values.
+* type conversion:                       Conversion.
+* types of variables <1>:                Typing and Comparison.
+* types of variables:                    Assignment Ops.
+* undefined functions:                   Function Caveats.
+* undocumented features:                 Undocumented.
+* uninitialized variables, as array subscripts: Uninitialized Subscripts.
+* uniq utility:                          Uniq Program.
+* uniq.awk:                              Uniq Program.
+* use of comments:                       Comments.
+* user information:                      Passwd Functions.
+* user-defined functions:                User-defined.
+* user-defined variables:                Using Variables.
+* uses of awk:                           What Is Awk.
+* using this book:                       This Manual.
+* values of characters as numbers:       Ordinal Functions.
+* variable shadowing:                    Definition Syntax.
+* variable typing:                       Typing and Comparison.
+* variables, user-defined:               Using Variables.
+* Wall, Larry:                           Future Extensions.
+* wc utility:                            Wc Program.
+* wc.awk:                                Wc Program.
+* Weinberger, Peter:                     History.
+* when to use awk:                       When.
+* while statement:                       While Statement.
+* word boundaries, matching:             GNU Regexp Operators.
+* word, regexp definition of:            GNU Regexp Operators.
+* wordfreq.sh:                           Word Sorting.
+* || operator:                           Boolean Ops.
+* ~ operator <1>:                        Typing and Comparison.
+* ~ operator <2>:                        Regexp Constants.
+* ~ operator <3>:                        Computed Regexps.
+* ~ operator <4>:                        Case-sensitivity.
+* ~ operator:                            Regexp Usage.
+
+
+
+Tag Table:
+Node: Top1197
+Node: Preface20700
+Ref: Preface-Footnote-121817
+Node: History22049
+Node: Manual History23407
+Node: Acknowledgements26997
+Node: What Is Awk30624
+Node: This Manual32278
+Node: Conventions34919
+Node: Sample Data Files36211
+Node: Getting Started39294
+Node: Names41602
+Ref: Names-Footnote-143099
+Node: Running gawk43171
+Node: One-shot44332
+Node: Read Terminal45719
+Node: Long47331
+Node: Executable Scripts48724
+Ref: Executable Scripts-Footnote-150374
+Ref: Executable Scripts-Footnote-250523
+Node: Comments50977
+Node: Very Simple52137
+Node: Two Rules54184
+Node: More Complex56363
+Node: Statements/Lines59479
+Node: Other Features63752
+Node: When64478
+Node: One-liners66412
+Node: Regexp69299
+Node: Regexp Usage70625
+Node: Escape Sequences72775
+Node: Regexp Operators78227
+Node: GNU Regexp Operators89260
+Node: Case-sensitivity92965
+Node: Leftmost Longest96080
+Node: Computed Regexps97615
+Node: Reading Files100272
+Node: Records102039
+Node: Fields108534
+Ref: Fields-Footnote-1111516
+Node: Non-Constant Fields111602
+Node: Changing Fields113888
+Node: Field Separators118295
+Node: Basic Field Splitting118997
+Node: Regexp Field Splitting122226
+Node: Single Character Fields124792
+Node: Command Line Field Separator125869
+Node: Field Splitting Summary129109
+Ref: Field Splitting Summary-Footnote-1131028
+Node: Constant Size131129
+Node: Multiple Line135166
+Node: Getline140574
+Node: Getline Intro141648
+Node: Plain Getline142611
+Node: Getline/Variable144875
+Node: Getline/File146017
+Node: Getline/Variable/File147327
+Node: Getline/Pipe149301
+Node: Getline/Variable/Pipe151391
+Node: Getline Summary152509
+Node: Printing154103
+Node: Print155171
+Node: Print Examples157271
+Node: Output Separators159882
+Node: OFMT161780
+Node: Printf163182
+Node: Basic Printf164086
+Node: Control Letters165620
+Node: Format Modifiers168308
+Node: Printf Examples172457
+Node: Redirection175236
+Node: Special Files179874
+Node: Close Files And Pipes185111
+Node: Expressions189172
+Node: Constants191378
+Node: Scalar Constants191857
+Ref: Scalar Constants-Footnote-1192717
+Node: Regexp Constants192861
+Node: Using Constant Regexps193323
+Node: Variables196524
+Node: Using Variables197178
+Node: Assignment Options198613
+Node: Conversion200557
+Node: Arithmetic Ops203738
+Node: Concatenation205872
+Node: Assignment Ops207227
+Node: Increment Ops212822
+Node: Truth Values215350
+Node: Typing and Comparison216398
+Node: Boolean Ops222298
+Node: Conditional Exp225991
+Node: Function Calls227668
+Node: Precedence230548
+Node: Patterns and Actions233936
+Node: Pattern Overview234362
+Node: Kinds of Patterns235137
+Node: Regexp Patterns236274
+Node: Expression Patterns236828
+Node: Ranges240480
+Node: BEGIN/END243199
+Node: Using BEGIN/END243668
+Node: I/O And BEGIN/END246630
+Node: Empty248646
+Node: Action Overview248945
+Node: Statements251516
+Node: If Statement253222
+Node: While Statement254725
+Node: Do Statement256756
+Node: For Statement257858
+Node: Break Statement261115
+Node: Continue Statement263386
+Node: Next Statement265382
+Node: Nextfile Statement267879
+Node: Exit Statement269793
+Node: Built-in Variables271803
+Node: User-modified272899
+Ref: User-modified-Footnote-1277688
+Node: Auto-set277750
+Ref: Auto-set-Footnote-1284073
+Node: ARGC and ARGV284279
+Node: Arrays286981
+Node: Array Intro288444
+Node: Reference to Elements292320
+Node: Assigning Elements294270
+Node: Array Example294772
+Node: Scanning an Array296491
+Node: Delete298821
+Node: Numeric Array Subscripts300881
+Node: Uninitialized Subscripts302787
+Node: Multi-dimensional304427
+Node: Multi-scanning307522
+Node: Built-in309165
+Node: Calling Built-in310154
+Node: Numeric Functions312125
+Ref: Numeric Functions-Footnote-1315673
+Node: String Functions315943
+Ref: String Functions-Footnote-1334729
+Ref: String Functions-Footnote-2334780
+Node: I/O Functions334873
+Ref: I/O Functions-Footnote-1340366
+Node: Time Functions340457
+Ref: Time Functions-Footnote-1348776
+Ref: Time Functions-Footnote-2348887
+Ref: Time Functions-Footnote-3349163
+Node: User-defined349307
+Node: Definition Syntax350019
+Node: Function Example354268
+Node: Function Caveats356598
+Node: Return Statement360469
+Node: Invoking Gawk363124
+Node: Options364359
+Ref: Options-Footnote-1373162
+Node: Other Arguments373187
+Node: AWKPATH Variable375833
+Ref: AWKPATH Variable-Footnote-1378281
+Node: Obsolete378581
+Node: Undocumented379247
+Node: Known Bugs379455
+Node: Library Functions380593
+Node: Portability Notes383012
+Node: Nextfile Function384296
+Ref: Nextfile Function-Footnote-1389001
+Node: Assert Function389171
+Node: Round Function392510
+Node: Ordinal Functions394155
+Ref: Ordinal Functions-Footnote-1397387
+Node: Join Function397606
+Node: Mktime Function399658
+Ref: Mktime Function-Footnote-1411149
+Node: Gettimeofday Function411232
+Node: Filetrans Function415244
+Node: Getopt Function418921
+Node: Passwd Functions430277
+Node: Group Functions438612
+Node: Library Names446509
+Node: Sample Programs450434
+Node: Clones450925
+Node: Cut Program452019
+Node: Egrep Program462048
+Node: Id Program469710
+Node: Split Program472981
+Node: Tee Program476359
+Node: Uniq Program479155
+Node: Wc Program486700
+Ref: Wc Program-Footnote-1490936
+Node: Miscellaneous Programs491117
+Node: Dupword Program492027
+Node: Alarm Program493698
+Node: Translate Program498243
+Ref: Translate Program-Footnote-1502730
+Ref: Translate Program-Footnote-2502873
+Node: Labels Program503053
+Ref: Labels Program-Footnote-1506512
+Node: Word Sorting506596
+Node: History Sorting510940
+Node: Extract Program512909
+Node: Simple Sed519866
+Node: Igawk Program523210
+Node: Language History536353
+Node: V7/SVR3.1537586
+Node: SVR4540239
+Node: POSIX541759
+Node: BTL543378
+Node: POSIX/GNU544142
+Node: Gawk Summary548573
+Node: Command Line Summary549397
+Node: Language Summary552373
+Ref: Language Summary-Footnote-1554630
+Node: Variables/Fields554753
+Node: Fields Summary555487
+Ref: Fields Summary-Footnote-1557215
+Node: Built-in Summary557273
+Node: Arrays Summary560918
+Node: Data Type Summary562211
+Node: Rules Summary564037
+Node: Pattern Summary565565
+Node: Regexp Summary567750
+Node: Actions Summary571132
+Node: Operator Summary572964
+Node: Control Flow Summary574191
+Node: I/O Summary574748
+Node: Printf Summary577737
+Node: Special File Summary581075
+Node: Built-in Functions Summary582753
+Node: Time Functions Summary586753
+Node: String Constants Summary587644
+Node: Functions Summary588964
+Node: Historical Features590025
+Node: Installation591523
+Node: Gawk Distribution592738
+Node: Getting593241
+Node: Extracting596226
+Node: Distribution contents597613
+Node: Unix Installation602527
+Node: Quick Installation603036
+Node: Configuration Philosophy604554
+Node: VMS Installation606956
+Node: VMS Compilation607495
+Node: VMS Installation Details609099
+Node: VMS Running610741
+Node: VMS POSIX612331
+Node: PC Installation613611
+Node: Atari Installation617014
+Node: Atari Compiling618198
+Node: Atari Using620107
+Node: Amiga Installation622953
+Node: Bugs624071
+Node: Other Versions627040
+Node: Notes628614
+Node: Compatibility Mode629221
+Node: Additions630064
+Node: Adding Code630762
+Node: New Ports636102
+Node: Future Extensions640270
+Node: Improvements642519
+Node: Glossary644387
+Node: Copying661452
+Node: Index680644
+
+End Tag Table
diff --git a/doc/gawk.texi b/doc/gawk.texi
index 75bf11f0..cf7c4ed5 100644
--- a/doc/gawk.texi
+++ b/doc/gawk.texi
@@ -21,9 +21,9 @@
 @c applies to, and when the document was updated.
 @set TITLE The GNU Awk User's Guide
 @set SUBTITLE Effective AWK Programming
-@set EDITION 1.0.1
+@set PATCHLEVEL 2
+@set EDITION 1.0.@value{PATCHLEVEL}
 @set VERSION 3.0
-@set PATCHLEVEL 1
 @set UPDATE-MONTH December 1996
 @iftex
 @set DOCUMENT book
@@ -2718,11 +2718,15 @@ program as it runs.  Case is significant by default because
 @code{IGNORECASE} (like most variables) is initialized to zero.
 
 @example
+@group
 x = "aB"
 if (x ~ /ab/) @dots{}   # this test will fail
+@end group
 
+@group
 IGNORECASE = 1
 if (x ~ /ab/) @dots{}   # now it will succeed
+@end group
 @end example
 
 In general, you cannot use @code{IGNORECASE} to make certain rules
@@ -3617,23 +3621,18 @@ of a record separately.  In @code{gawk}, this is easy to do, you
 simply assign the null string (@code{""}) to @code{FS}. In this case,
 each individual character in the record will become a separate field.
 Here is an example:
-@c extra verbiage due to page boundaries
-
-@example
-echo a b | gawk 'BEGIN @{ FS = "" @}
-                 @{ 
-                     for (i = 1; i <= NF; i = i + 1)
-                         print "Field", i, "is", $i
-                 @}'
-@end example
-
-@noindent
-The output from this is:
 
 @example
-Field 1 is a
-Field 2 is
-Field 3 is b
+@group
+$ echo a b | gawk 'BEGIN @{ FS = "" @}
+>                  @{ 
+>                      for (i = 1; i <= NF; i = i + 1)
+>                          print "Field", i, "is", $i
+>                  @}'
+@print{} Field 1 is a
+@print{} Field 2 is
+@print{} Field 3 is b
+@end group
 @end example
 
 @cindex dark corner
@@ -10312,7 +10311,7 @@ $ awk '@{ print $1 + $2 @}' | cat
 @end example
 
 @noindent
-Here, no output is printed until after the @kbd{Control-D} is typed, since
+Here, no output is printed until after the @kbd{Control-d} is typed, since
 it is all buffered, and sent down the pipe to @code{cat} in one shot.
 
 @c fakenode --- for prepinfo
@@ -14548,8 +14547,10 @@ BEGIN    \
                 split(pw, a, ":")
                 printf("(%s)", a[1])
             @}
+@group
             if (i < NF)
                 printf(",")
+@end group
         @}
     @}
     print ""
@@ -14599,8 +14600,7 @@ is used as the prefix for the output file names.
 
 # usage: split [-num] [file] [outname]
 
-BEGIN    \
-@{
+BEGIN @{
     outfile = "x"    # default
     count = 1000
     if (ARGC > 4)
@@ -14720,33 +14720,41 @@ Finally, @code{awk} is forced to read the standard input by setting
 
 @findex tee.awk
 @example
-@c @group
+@group
 @c file eg/prog/tee.awk
 # tee.awk --- tee in awk
 # Arnold Robbins, arnold@@gnu.ai.mit.edu, Public Domain
 # May 1993
 # Revised December 1995
+@end group
 
+@group
 BEGIN    \
 @{
     for (i = 1; i < ARGC; i++)
         copy[i] = ARGV[i]
+@end group
 
+@group
     if (ARGV[1] == "-a") @{
         append = 1
         delete ARGV[1]
         delete copy[1]
         ARGC--
     @}
+@end group
+@group
     if (ARGC < 2) @{
         print "usage: tee [-a] file ..." > "/dev/stderr"
         exit 1
     @}
+@end group
+@group
     ARGV[1] = "-"
     ARGC = 2
 @}
 @c endfile
-@c @end group
+@end group
 @end example
 
 The single rule does all the work.  Since there is no pattern, it is
@@ -18398,7 +18406,7 @@ You can copy it from someone else who already has it.
 @item
 You can order @code{gawk} directly from the Free Software Foundation.
 Software distributions are available for Unix, MS-DOS, and VMS, on
-tape, CD-ROM, or floppies (MS-DOS only).  The address is:
+tape and CD-ROM.  The address is:
 
 @quotation
 Free Software Foundation @*
diff --git a/getopt.c b/getopt.c
index 7306888b..cdd5a965 100644
--- a/getopt.c
+++ b/getopt.c
@@ -49,8 +49,10 @@
    program understand `configure --with-gnu-libc' and omit the object files,
    it is simpler to just do this in the source for each such file.  */
 
+/* Unfortunately, for gawk, this version is New And Improved, and must
+   be used. This will be fixed for GNU LIBC 2 
 #if defined (_LIBC) || !defined (__GNU_LIBRARY__)
-
+*/
 
 /* This needs to come after some library #include
    to get __GNU_LIBRARY__ defined.  */
@@ -659,6 +661,7 @@ _getopt_internal (argc, argv, optstring, longopts, longind, long_only)
 	      c = ':';
 	    else
 	      c = '?';
+	    return c;
 	  }
 	else
 	  /* We already incremented `optind' once;
@@ -812,6 +815,7 @@ getopt (argc, argv, optstring)
 			   0);
 }
 
+/* no close on purpose (gawk)
 #endif	/* _LIBC or not __GNU_LIBRARY__.  */
 
 #ifdef TEST
diff --git a/getopt1.c b/getopt1.c
index 6fea28c1..628bfd63 100644
--- a/getopt1.c
+++ b/getopt1.c
@@ -47,7 +47,10 @@
    program understand `configure --with-gnu-libc' and omit the object files,
    it is simpler to just do this in the source for each such file.  */
 
+/* Unfortunately, for gawk, this version is New And Improved, and must
+   be used. This will be fixed for GNU LIBC 2 
 #if defined (_LIBC) || !defined (__GNU_LIBRARY__)
+*/
 
 
 /* This needs to come after some library #include
@@ -90,6 +93,7 @@ getopt_long_only (argc, argv, options, long_options, opt_index)
 }
 
 
+/* no close on purpose (gawk)
 #endif	/* _LIBC or not __GNU_LIBRARY__.  */
 
 #ifdef TEST
diff --git a/patchlevel.h b/patchlevel.h
index 131713a8..c6161a1f 100644
--- a/patchlevel.h
+++ b/patchlevel.h
@@ -1 +1 @@
-#define PATCHLEVEL	1
+#define PATCHLEVEL	2
diff --git a/pc/ChangeLog b/pc/ChangeLog
index 04e5b419..b750e922 100644
--- a/pc/ChangeLog
+++ b/pc/ChangeLog
@@ -1,3 +1,11 @@
+Wed Dec 25 11:25:22 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.2: Release tar file made.
+
+Tue Dec 10 23:09:26 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.1: Release tar file made.
+
 Thu Aug  1 19:46:00 1996  Scott Deifik       <scottd@amgen.com>
 
 	* Makefile: Changes for MSC 8.
diff --git a/posix/ChangeLog b/posix/ChangeLog
index 570c031b..e025b89d 100644
--- a/posix/ChangeLog
+++ b/posix/ChangeLog
@@ -1,3 +1,11 @@
+Wed Dec 25 11:25:22 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.2: Release tar file made.
+
+Tue Dec 10 23:09:26 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.1: Release tar file made.
+
 Wed Jan 10 22:58:55 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
 
 	* ChangeLog created.
diff --git a/stamp-h.in b/stamp-h.in
index 6d7105ef..1fee4d60 100644
--- a/stamp-h.in
+++ b/stamp-h.in
@@ -1 +1 @@
-Tue Dec 10 22:48:08 EST 1996
+Wed Dec 18 10:27:30 EST 1996
diff --git a/test/ChangeLog b/test/ChangeLog
index 53a1b541..722d2e6a 100644
--- a/test/ChangeLog
+++ b/test/ChangeLog
@@ -1,3 +1,11 @@
+Wed Dec 25 11:25:22 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.2: Release tar file made.
+
+Tue Dec 10 23:09:26 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.1: Release tar file made.
+
 Thu Nov  7 09:12:20 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
 
 	* Makefile.in (splitvar): new test case.
diff --git a/vms/ChangeLog b/vms/ChangeLog
index 4d5a0918..d8992bb4 100644
--- a/vms/ChangeLog
+++ b/vms/ChangeLog
@@ -1,3 +1,31 @@
+Wed Dec 25 11:25:22 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.2: Release tar file made.
+
+Mon Dec 23 20:51:27 1996  Pat Rankin  <rankin@eql.caltech.edu>
+
+	* vms_misc.c (vms_bcopy):  `bcopy' is defined as this in redirect.h.
+
+Thu Dec 19 17:49:31 1996  Pat Rankin  <rankin@eql.caltech.edu>
+
+	* redirect.h (strcasecmp, strncasecmp, tzset, tzname,
+	  daylight, timezone, altzone, bcopy, popen, pclose, unlink):
+	  New macros to avoid conflict with VMS V7.x DECC$SHR symbols.
+	  (close, dup, dup2, read):  Declare with full prototypes.
+	  (fstat, stat):  Ditto, and guard against conflicting DEC C
+	  declarations (which might have trailing elipsis).
+	* vms_misc.c (tzset, tzname, daylight, timezone, altzone):
+	  Suppress these if compiled with VMS_V7 defined [not supported].
+
+Mon Dec 16 14:32:08 1996  Pat Rankin  <rankin@eql.caltech.edu>
+
+	* vms_popen (popen):  Delete unprototyped declaration of strcmp()
+	  to avoid conflict with a strcmp macro in DEC C V5.0 header files.
+
+Tue Dec 10 23:09:26 1996  Arnold D. Robbins  <arnold@skeeve.atl.ga.us>
+
+	* Release 3.0.1: Release tar file made.
+
 Fri Dec  6 20:55:57 1996  Pat Rankin  <rankin@eql.caltech.edu>
 
 	* redirect.h, vms-conf.h:  Refine Sep 20th change:  include
diff --git a/vms/redirect.h b/vms/redirect.h
index ce58901d..18659b5e 100644
--- a/vms/redirect.h
+++ b/vms/redirect.h
@@ -42,6 +42,15 @@
 #define regerror	gnu_regerror
 #ifndef VMS_POSIX
 #define strftime	gnu_strftime	/* always use missing/strftime.c */
+#define strcasecmp	gnu_strcasecmp
+#define strncasecmp	gnu_strncasecmp
+#ifndef VMS_V7
+#define tzset		fake_tzset
+#define tzname		fake_tzname
+#define daylight	fake_daylight
+#define timezone	fake_timezone
+#define altzone		fake_altzone
+#endif
 #endif
 
 #ifdef STDC_HEADERS
@@ -54,10 +63,16 @@
 #else	/* awk.h, not POSIX */
 
 /* some macros to redirect to code in vms/vms_misc.c */
+#ifndef bcopy
+#define bcopy		vms_bcopy
+#endif
 #define exit		vms_exit
 #define open		vms_open
+#define popen		vms_popen
+#define pclose		vms_pclose
 #define strerror	vms_strerror
 #define strdup		vms_strdup
+#define unlink		vms_unlink
 extern void  exit P((int));
 extern int   open P((const char *,int,...));
 extern char *strerror P((int));
@@ -80,7 +95,15 @@ extern int isatty P((int));
 #ifndef fileno
 extern int fileno P((FILE *));
 #endif
-extern int close(), dup(), dup2(), fstat(), read(), stat();
+extern int close P((int));
+extern int dup P((int));
+extern int dup2 P((int, int));
+extern int read P((int, void *, int));
+#if defined(__DECC) && !defined(__CAN_USE_EXTERN_PREFIX)
+struct stat;
+extern int fstat P((int, struct stat *));
+extern int stat P((const char *, struct stat *));
+#endif
 extern int getpgrp P((void));
 
 #endif	/* not VMS_POSIX and not IN_CONFIG_H */
diff --git a/vms/vms_misc.c b/vms/vms_misc.c
index d876534c..8e12c154 100644
--- a/vms/vms_misc.c
+++ b/vms/vms_misc.c
@@ -169,6 +169,8 @@ vms_devopen( const char *name, int mode )
     return (file && *file && *name == '\0') ? fileno(file) : -1;
 }
 
+
+#ifndef VMS_V7
     /*
      * VMS prior to V7.x has no timezone support unless DECnet/OSI is used.
      */
@@ -181,6 +183,8 @@ void tzset(void)
 {
     return;
 }
+#endif	/*VMS_V7*/
+
 
 /* getpgrp() -- there's no such thing as process group under VMS;
  *		job tree might be close enough to be useful though.
@@ -191,10 +195,7 @@ int getpgrp(void)
 }
 
 #ifndef __GNUC__
-# ifdef bcopy
-#  undef bcopy
-# endif
-void bcopy( const char *src, char *dst, int len )
+void vms_bcopy( const char *src, char *dst, int len )
 {
     (void) memcpy(dst, src, len);
 }
diff --git a/vms/vms_popen.c b/vms/vms_popen.c
index d92dca90..e5829442 100644
--- a/vms/vms_popen.c
+++ b/vms/vms_popen.c
@@ -47,7 +47,7 @@ pclose( FILE *current )
 }
 
 int
-fork()
+fork( void )
 {
     fatal(" Internal error ('fork' not implemented)");
     /* NOT REACHED */
@@ -70,6 +70,11 @@ fork()
 #include <errno.h>
 #include <lnmdef.h>	/* logical name definitions */
 
+#ifndef STDC_HEADERS
+extern int strcmp P((const char*, const char *));
+#endif
+extern char *mktemp P((char *));
+
 static void push_logicals P((void));
 static void pop_logicals P((void));
 static Itm *save_translation P((const Dsc *));
@@ -97,8 +102,8 @@ FILE *
 popen( const char *command, const char *mode )
 {
     FILE *current;
-    char *name, *mktemp();
-    int   cur, strcmp();
+    char *name;
+    int   cur;
     pipemode curmode;
 
     if (strcmp(mode, "r") == 0)