doc: clarify exit status

Reported by Santiago Ruano Rincón in: http://bugs.gnu.org/18651
* doc/grep.in.1 (EXIT STATUS):
* doc/grep.texi (Exit Status): Clarify.

2 files changed, 10 insertions, 23 deletions

diff --git a/doc/grep.in.1 b/doc/grep.in.1
index 00d030ac..16b94b28 100644
--- a/doc/grep.in.1
+++ b/doc/grep.in.1
@@ -1143,23 +1143,15 @@ when
 is not set.
 .
 .SH "EXIT STATUS"
-Normally, the exit status is 0 if selected lines are found and 1 otherwise.
-But the exit status is 2 if an error occurred, unless the
+Normally the exit status is 0 if a line is selected, 1 if no lines
+were selected, and 2 if an error occurred.  However, if the
 .B \-q
 or
 .B \-\^\-quiet
 or
 .B \-\^\-silent
-option is used and a selected line is found.
-Note, however, that \s-1POSIX\s0 only mandates, for programs such as
-.BR grep ,
-.BR cmp ,
-and
-.BR diff ,
-that the exit status in case of error be greater than 1;
-it is therefore advisable, for the sake of portability,
-to use logic that tests for this general condition
-instead of strict equality with\ 2.
+is used and a line is selected, the exit status is 0 even if an error
+occurred.
 .
 .SH COPYRIGHT
 Copyright 1998-2000, 2002, 2005-2014 Free Software Foundation, Inc.
diff --git a/doc/grep.texi b/doc/grep.texi
index d7adcadd..da9a1bee 100644
--- a/doc/grep.texi
+++ b/doc/grep.texi
@@ -1025,17 +1025,12 @@ and only when @env{POSIXLY_CORRECT} is not set.
 @cindex exit status
 @cindex return status
 
-Normally, the exit status is 0 if selected lines are found and 1 otherwise.
-But the exit status is 2 if an error occurred, unless the @option{-q} or
-@option{--quiet} or @option{--silent} option is used and a selected line
-is found.
-Note, however, that POSIX only mandates,
-for programs such as @command{grep}, @command{cmp}, and @command{diff},
-that the exit status in case of error be greater than 1;
-it is therefore advisable, for the sake of portability,
-to use logic that tests for this general condition
-instead of strict equality with@ 2.
-
+Normally the exit status is 0 if a line is selected, 1 if no lines
+were selected, and 2 if an error occurred.  However, if the
+@option{-q} or @option{--quiet} or @option{--silent} option is used
+and a line is selected, the exit status is 0 even if an error
+occurred.  Other @command{grep} implementations may exit with status
+greater than 2 on error.
 
 @node grep Programs
 @section @command{grep} Programs