Dan Manthey <[EMAIL PROTECTED]> writes:
> By the way, Noah pointed out that grep -q wasn't portable. This is not
> mentioned in the autoconf docs.
Ouch. I thought everybody already knew that grep -q wasn't portable. :-)
It is mentioned in the grep manual, of all places, but I've installed this:
2005-02-09 Paul Eggert <[EMAIL PROTECTED]>
* doc/autoconf.texi (Limitations of Usual Tools): Document that
grep -q isn't portable. Improve grep -s explanation.
Problem reported by Dan Manthey.
--- autoconf.texi 8 Feb 2005 17:27:04 -0000 1.877
+++ autoconf.texi 10 Feb 2005 00:41:24 -0000 1.878
@@ -11702,8 +11702,12 @@ while @acronym{GNU} @command{find} repor
@item @command{grep}
@c -----------------
@prindex @command{grep}
-Don't use @samp{grep -s} to suppress output, because @samp{grep -s} on
-System V does not suppress output, only error messages. Instead,
+Don't use @samp{grep -q} to suppress output, because many @command{grep}
+implementations (e.g., Solaris 10) do not support @option{-q}.
+Don't use @samp{grep -s} to suppress output either, because Posix
+says @option{-s} does not suppress output, only some error messages;
+also, the @option{-s} option of traditional @command{grep} behaved
+like @option{-q} does in most modern implementations. Instead,
redirect the standard output and standard error (in case the file
doesn't exist) of @code{grep} to @file{/dev/null}. Check the exit
status of @code{grep} to determine whether it found a match.
@@ -11711,7 +11715,7 @@ status of @code{grep} to determine wheth
Some traditional @command{grep} implementations do not work on long
input lines. Also, many implementations do not support multiple regexps
with @option{-e}: they either reject @samp{-e} entirely (e.g., Solaris
-9) or honor only the last pattern (e.g., @acronym{IRIX} 6.5). To
+10) or honor only the last pattern (e.g., @acronym{IRIX} 6.5). To
work around these problems, invoke @code{AC_PROG_GREP} and then use
@code{$GREP}.
