Re: [PATCH] Fix exit status of signal handlers in shell scripts

[Ralf Wildenhues]

* Dmitry V. Levin wrote on Sun, Jan 31, 2010 at 01:04:01PM CET:
> On Sun, Jan 31, 2010 at 08:05:20AM +0100, Ralf Wildenhues wrote:
> > Can you please explain whose fault this is?  Is that a kernel issue, a
> > shell issue, or expected behavior given a POSIX system?
> 
> It is expected behaviour.

> > What are the "other cases"
> > you mention, where no process was terminated by the signal, but the
> > signal delivered somewhere nonethess?
> 
> A moment when the signal can be delivered to the shell process is not
> necessarily the moment when an external command is executed.  The signal
> can be delivered when a builtin is executed, or even when nothing is
> executed yet.  In this case, the exit status of the last command run
> before the trap has nothing related to the just delivered signal.

Thanks for the explanation.  As I understand SUSv3, the same should hold
for builtin commands as for external ones.  But I agree that nothing may
be executed, and there is no limitation for $? then.

However, SIGINT should not cause 128+TERM, so it would be more precise
to exit with a status that reflected the actual signal given, similar to
how configure scripts adjust the per-signal trap, for the scripts which
have more than one signal trapped.

Thanks,
Ralf