docs: mention ksh file descriptor limitation

* doc/autoconf.texi (File Descriptors): Document issue with fd 10
and above.
Reported by Ralf Wildenhues.

diff --git a/ChangeLog b/ChangeLog
index 278a56564913c4ecbfe725adfdd377956322ded8..0ef1fd3d4f0b3335adc767aeabe8f50269b5975d 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2010-07-29  Eric Blake  <eblake@redhat.com>
 
+       docs: mention ksh file descriptor limitation
+       * doc/autoconf.texi (File Descriptors): Document issue with fd 10
+       and above.
+       Reported by Ralf Wildenhues.
+
        docs: mention cd limitation
        * doc/autoconf.texi (Limitations of Builtins) <cd>: Document
        issues with empty argument.

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 493b9dcc85f2ef95c0d4393d70eab56680d8c854..7e804a7345a6409ab9d2e29fd889f1d5485eb3c6 100644 (file)
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -15041,6 +15041,20 @@ descriptor 4 had a special use on the Stardent/Kubota Titan (circa
 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}:
+
+@example
+$ @kbd{bash -c 'exec 10>&-'; echo $?}
+0
+$ @kbd{ksh -c 'exec 9>&-'; echo $?}
+0
+$ @kbd{ksh -c 'exec 10>&-'; echo $?}
+ksh[1]: exec: 10: not found
+127
+@end example
+
 @node File System Conventions
 @section File System Conventions
 @cindex File system conventions