a "replacement" for awk and sedperl-1.0

[  Perl is kind of designed to make awk and sed semi-obsolete.  This posting
   will include the first 10 patches after the main source.  The following
   description is lifted from Larry's manpage. --r$  ]

   Perl is a interpreted language optimized for scanning arbitrary text
   files, extracting information from those text files, and printing
   reports based on that information.  It's also a good language for many
   system management tasks.  The language is intended to be practical
   (easy to use, efficient, complete) rather than beautiful (tiny,
   elegant, minimal).  It combines (in the author's opinion, anyway) some
   of the best features of C, sed, awk, and sh, so people familiar with
   those languages should have little difficulty with it.  (Language
   historians will also note some vestiges of csh, Pascal, and even
   BASIC-PLUS.) Expression syntax corresponds quite closely to C
   expression syntax.  If you have a problem that would ordinarily use sed
   or awk or sh, but it exceeds their capabilities or must run a little
   faster, and you don't want to write the silly thing in C, then perl may
   be for you.  There are also translators to turn your sed and awk
   scripts into perl scripts.

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+.rn '' }`
+''' $Header: a2p.man,v 1.0 87/12/18 17:23:56 root Exp $
+''' 
+''' $Log:	a2p.man,v $
+''' Revision 1.0  87/12/18  17:23:56  root
+''' Initial revision
+''' 
+''' 
+.de Sh
+.br
+.ne 5
+.PP
+\fB\\$1\fR
+.PP
+..
+.de Sp
+.if t .sp .5v
+.if n .sp
+..
+.de Ip
+.br
+.ie \\n.$>=3 .ne \\$3
+.el .ne 3
+.IP "\\$1" \\$2
+..
+'''
+'''     Set up \*(-- to give an unbreakable dash;
+'''     string Tr holds user defined translation string.
+'''     Bell System Logo is used as a dummy character.
+'''
+.tr \(bs-|\(bv\*(Tr
+.ie n \{\
+.ds -- \(bs-
+.if (\n(.H=4u)&(1m=24u) .ds -- \(bs\h'-12u'\(bs\h'-12u'-\" diablo 10 pitch
+.if (\n(.H=4u)&(1m=20u) .ds -- \(bs\h'-12u'\(bs\h'-8u'-\" diablo 12 pitch
+.ds L" ""
+.ds R" ""
+.ds L' '
+.ds R' '
+'br\}
+.el\{\
+.ds -- \(em\|
+.tr \*(Tr
+.ds L" ``
+.ds R" ''
+.ds L' `
+.ds R' '
+'br\}
+.TH A2P 1 LOCAL
+.SH NAME
+a2p - Awk to Perl translator
+.SH SYNOPSIS
+.B a2p [options] filename
+.SH DESCRIPTION
+.I A2p
+takes an awk script specified on the command line (or from standard input)
+and produces a comparable
+.I perl
+script on the standard output.
+.Sh "Options"
+Options include:
+.TP 5
+.B \-D<number>
+sets debugging flags.
+.TP 5
+.B \-F<character>
+tells a2p that this awk script is always invoked with this -F switch.
+.TP 5
+.B \-n<fieldlist>
+specifies the names of the input fields if input does not have to be split into
+an array.
+If you were translating an awk script that processes the password file, you
+might say:
+.sp
+	a2p -7 -nlogin.password.uid.gid.gcos.shell.home
+.sp
+Any delimiter will do to separate the field names.
+.TP 5
+.B \-<number>
+causes a2p to assume that input will always have that many fields.
+.Sh "Considerations"
+A2p cannot do as good a job translating as a human would, but it usually
+does pretty well.
+There are some areas where you may want to examine the perl script produced
+and tweak it some.
+Here are some of them, in no particular order.
+.PP
+The split operator in perl always strips off all null fields from the end.
+Awk does NOT do this, if you've set FS.
+If the perl script splits to an array, the field count may not reflect
+what you expect.
+Ordinarily this isn't a problem, since nonexistent array elements have a null
+value, but if you rely on NF in awk, you could be in for trouble.
+Either force the number of fields with \-<number>, or count the number of
+delimiters another way, e.g. with y/:/:/.
+Or add something non-null to the end before you split, and then pop it off
+the resulting array.
+.PP
+There is an awk idiom of putting int() around a string expression to force
+numeric interpretation, even though the argument is always integer anyway.
+This is generally unneeded in perl, but a2p can't tell if the argument
+is always going to be integer, so it leaves it in.
+You may wish to remove it.
+.PP
+Perl differentiates numeric comparison from string comparison.
+Awk has one operator for both that decides at run time which comparison
+to do.
+A2p does not try to do a complete job of awk emulation at this point.
+Instead it guesses which one you want.
+It's almost always right, but it can be spoofed.
+All such guesses are marked with the comment \*(L"#???\*(R".
+You should go through and check them.
+.PP
+Perl does not attempt to emulate the behavior of awk in which nonexistent
+array elements spring into existence simply by being referenced.
+If somehow you are relying on this mechanism to create null entries for
+a subsequent for...in, they won't be there in perl.
+.PP
+If a2p makes a split line that assigns to a list of variables that looks
+like (Fld1, Fld2, Fld3...) you may want
+to rerun a2p using the \-n option mentioned above.
+This will let you name the fields throughout the script.
+If it splits to an array instead, the script is probably referring to the number
+of fields somewhere.
+.PP
+The exit statement in awk doesn't necessarily exit; it goes to the END
+block if there is one.
+Awk scripts that do contortions within the END block to bypass the block under
+such circumstances can be simplified by removing the conditional
+in the END block and just exiting directly from the perl script.
+.PP
+Perl has two kinds of array, numerically-indexed and associative.
+Awk arrays are usually translated to associative arrays, but if you happen
+to know that the index is always going to be numeric you could change
+the {...} to [...].
+Iteration over an associative array is done with each(), but
+iteration over a numeric array is NOT.
+You need a for loop, or while loop with a pop() or shift(), so you might
+need to modify any loop that is iterating over the array in question.
+.PP
+Arrays which have been split into are assumed to be numerically indexed.
+The usual perl idiom for iterating over such arrays is to use pop() or shift()
+and assign the resulting value to a variable inside the conditional of the
+while loop.
+This is destructive to the array, however, so a2p can't assume this is
+reasonable.
+A2p will write a standard for loop with a scratch variable.
+You may wish to change it to a pop() loop for more efficiency, presuming
+you don't want to keep the array around.
+.PP
+Awk starts by assuming OFMT has the value %.6g.
+Perl starts by assuming its equivalent, $#, to have the value %.20g.
+You'll want to set $# explicitly if you use the default value of OFMT.
+.PP
+Near the top of the line loop will be the split operation that is implicit in
+the awk script.
+There are times when you can move this down past some conditionals that
+test the entire record so that the split is not done as often.
+.PP
+There may occasionally be extra parentheses that you can remove.
+.PP
+For aesthetic reasons you may wish to change the array base $[ from 1 back
+to the default of 0, but remember to change all array subscripts AND
+all substr() and index() operations to match.
+.PP
+Cute comments that say "# Here is a workaround because awk is dumb" are not
+translated.
+.PP
+Awk scripts are often embedded in a shell script that pipes stuff into and
+out of awk.
+Often the shell script wrapper can be incorporated into the perl script, since
+perl can start up pipes into and out of itself, and can do other things that
+awk can't do by itself.
+.SH ENVIRONMENT
+A2p uses no environment variables.
+.SH AUTHOR
+Larry Wall <lwall@devvax.Jpl.Nasa.Gov>
+.SH FILES
+.SH SEE ALSO
+perl	The perl compiler/interpreter
+.br
+s2p	sed to perl translator
+.SH DIAGNOSTICS
+.SH BUGS
+It would be possible to emulate awk's behavior in selecting string versus
+numeric operations at run time by inspection of the operands, but it would
+be gross and inefficient.
+Besides, a2p almost always guesses right.
+.PP
+Storage for the awk syntax tree is currently static, and can run out.
+.rn }` ''