Re: Value of $? after signal

[Bart Schaefer <schaefer@brasslantern.com>]

On Sep 10, 10:50am, David Korn wrote:
}
[Bart wrote:]
} > [I just sent a very similar message to the zsh-workers list.]
} > 
} >        The  return  value of a simple command is its exit status,
} >        or 128+n if the command is terminated by signal n.
} > 
} > What does ksh do?
} 
} First of all, ksh uses
} 	256+signo
} for processes that terminate due to a signal.  Otherwise, there
} is no way to distinguish between a process that does exit(130)
} and one that terminated due to a SIGINT.

I was looking at this a bit more.  There are a couple of places in exec.c
and jobs.c where zsh tests (the equivalent of) `lastval & 0200' to decide
whether a child process got a signal.  That means a child that explicitly
calls exit(130) can fool zsh into interrupting a loop (jobs.c:338) or (I
think) "propagating" a signal to the entire process group (exec.c:1070).

To see the jobs.c problem, compare:

    yes | for x in a b c; do echo $x; (exit 2); echo $?; done

    yes | for x in a b c; do echo $x; (exit 130); echo $?; done

I haven't come up with an example for the exec.c issue, but it should be
something similar to the above (requires a loop on the right of a pipe).

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net