On 09/29/2011 02:51 AM, Stefano Lattarini wrote:
Some Korn shells, when a child process die due to signal number
n, can leave in $? an exit status of 256+n, instead of the "more
standard" 128+n. See also Austin Group issue 0000051:
<http://www.austingroupbugs.net/view.php?id=51>
* doc/autoconf.texi (Signal handling): Document the described Korn
Shell behaviour, and some of its possible shortcomings.
Assuming you already picked up Peter's good tweaks, I'll only add a
couple more:
+++ b/ChangeLog
@@ -1,9 +1,13 @@
-2011-09-26 Eric Blake<ebl...@redhat.com>
-
- docs: relax documentation license by dropping cover text
- * doc/autoconf.texi (copying): Drop front- and back-cover texts.
- * NEWS: Document this.
- Reported by Brian Gough.
+2011-09-29 Stefano Lattarini<stefano.lattar...@gmail.com>
+
+ docs: korn shells can have $?> 256 for signal-terminated children
+ Some Korn shells, when a child process die due to signal number
+ n, can leave in $? an exit status of 256+n, instead of the "more
+ standard" 128+n. See also Austin Group issue 0000051:
+ <http://www.austingroupbugs.net/view.php?id=51>
+ * doc/autoconf.texi (Signal handling): Document the described Korn
+ Shell behaviour, and some of its possible shortcomings.
+ Suggestion by Eric Blake.
Fix this. Don't know what happened here, but you don't want to nuke the
old entry when you rebase to add your entry on top.
+@noindent
+This @command{ksh} behaviour is allowed by POSIX, if implemented with
s/behaviour/behavior/ - the manual favors US spellings.
+due care; see this @uref{http://www.austingroupbugs.net/view.php?id=51,
+Austin Group discussion} for more background. However, if it is not
+implemented with proper care, such a behaviour might can cause problems
again.
+@noindent
+If @command{wrapped_command} is interrupted by a @code{SIGHUP} (which
+has signal number 1), @code{ret} will be set to 257. Unless the
+@command{exit} shell builtin is smart enough to understand that such
+a value can only have been originated from a signal, and adjust the
s/only have been originated/only have originated/
+final wait status of the shell appropriately, the value 257 will just
+get truncated to 1 by the closing @code{exit} call, so that a caller
+of the script will have no way to determine that termination by a
+signal was involved. Observe the different behaviour of AT&T
behavior, again
+@code{ksh93} (2011) and @code{bash} 4.1.5 on Debian:
+
+@example
+$ @kbd{cat> foo.sh}
I'd write this as @kbd{cat >foo.sh <<\EOF}
+#!/bin/sh
+sh -c 'kill -1 $$'
+ret=$?
+echo $ret
+exit $ret
and use EOF here, since that's easier than representing the ^D that
otherwise is needed to end the cat.
ACK with those additional fixes. And sorry for my delayed review.
--
Eric Blake ebl...@redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
