Here's a patch to mention two shell portability problems, that I noticed during gnulib work <https://lists.gnu.org/archive/html/bug-gnulib/2020-09/msg00080.html>.
doc: Mention two more shell portability problems. * doc/autoconf.texi (File Descriptors): Mention a problem of Solaris 10. Mention that a known problem also occurs in dash.
>From e41b8b2b2a59ee765e2c7b583be68101c2da52eb Mon Sep 17 00:00:00 2001 From: Bruno Haible <[email protected]> Date: Fri, 18 Sep 2020 01:17:38 +0200 Subject: [PATCH] doc: Mention two more shell portability problems. * doc/autoconf.texi (File Descriptors): Mention a problem of Solaris 10. Mention that a known problem also occurs in dash. --- doc/autoconf.texi | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/doc/autoconf.texi b/doc/autoconf.texi index 43df8f3..164175b 100644 --- a/doc/autoconf.texi +++ b/doc/autoconf.texi @@ -15645,6 +15645,18 @@ $ @kbd{dash -c ': 1<>file'; cat file} $ rm a @end example +Solaris 10 @code{sh} executes redirected compound commands in a subshell, +while other shells don't: + +@example +$ @kbd{sh -c 'foo=0; foo=1 2>/dev/null; echo $foo'} +1 +$ @kbd{sh -c 'foo=0; @{ foo=1; @} 2>/dev/null; echo $foo'} +0 +$ @kbd{bash -c 'foo=0; @{ foo=1; @} 2>/dev/null; echo $foo'} +1 +@end example + When catering to old systems, don't redirect the same file descriptor several times, as you are doomed to failure under Ultrix. @@ -15745,8 +15757,8 @@ obsolete, so it's now safe to treat file descriptors 3 and 4 like any other file descriptors. On the other hand, you can't portably use multi-digit file descriptors. -Solaris @command{ksh} doesn't understand any file descriptor larger than -@samp{9}: +Solaris @command{ksh} and @command{dash} 0.5.8 don't understand any file +descriptor larger than @samp{9}: @example $ @kbd{bash -c 'exec 10>&-'; echo $?} @@ -15756,6 +15768,11 @@ $ @kbd{ksh -c 'exec 9>&-'; echo $?} $ @kbd{ksh -c 'exec 10>&-'; echo $?} ksh[1]: exec: 10: not found 127 +$ @kbd{dash -c 'exec 9>&-'; echo $?} +0 +$ @kbd{dash -c 'exec 10>&-'; echo $?} +exec: 1: 10: not found +2 @end example @c <https://lists.gnu.org/archive/html/bug-autoconf/2011-09/msg00004.html> -- 2.7.4
