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author | Bruno Haible <bruno@clisp.org> | 2020-09-18 01:17:38 +0200 |
---|---|---|
committer | Zack Weinberg <zackw@panix.com> | 2020-09-18 09:22:10 -0400 |
commit | c1f55d8f0a72175ba7eecc3e132b618958b13a2f (patch) | |
tree | 2b0722cfd5f759eb74562cbfa7733b95985b0b75 | |
parent | 9b8e746a49085df1ccff255605411cf3ba2989e9 (diff) | |
download | autoconf-c1f55d8f0a72175ba7eecc3e132b618958b13a2f.tar.gz |
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.
-rw-r--r-- | doc/autoconf.texi | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/doc/autoconf.texi b/doc/autoconf.texi index 4bd6e9e7..38646a16 100644 --- a/doc/autoconf.texi +++ b/doc/autoconf.texi @@ -15656,6 +15656,18 @@ $ @kbd{dash -c ': 1<>file'; cat file} $ rm a @end example +Solaris 10 @code{/bin/sh} executes redirected compound commands +in a subshell, while other shells don't: + +@example +$ @kbd{/bin/sh -c 'foo=0; @{ foo=1; @} 2>/dev/null; echo $foo'} +0 +$ @kbd{ksh -c 'foo=0; @{ foo=1; @} 2>/dev/null; echo $foo'} +1 +$ @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. @@ -15756,8 +15768,8 @@ 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}: +@command{dash} and Solaris @command{ksh} don't understand any file +descriptor larger than @samp{9}: @example $ @kbd{bash -c 'exec 10>&-'; echo $?} @@ -15767,6 +15779,11 @@ $ @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> |