Subject: Re: sh exit trap problem
To: J Chapman Flack <>
From: Greywolf <>
List: current-users
Date: 01/10/2005 14:48:55
[Thus spake J Chapman Flack ("JCF: ") 3:09pm...]

JCF: Wolfgang Rupprecht wrote:
JCF: > Under bash, when [the shell executing the following script exits on an
JCF: > untrapped SIGINT, the EXIT trap is taken].  Under sh, nothing happens other
JCF: > than the shell script terminating immediately.  Is this a bug or
JCF: > simply undefined behavior that sh is implementing differently?
JCF: >
JCF: >     #!/bin/sh
JCF: >     # this sets the handler correctly in bash, but not in /bin/sh
JCF: >     trap "echo caught pseudo-sig EXIT" 0
JCF: >     sleep 3
JCF: That's a good question - I just tried in a few shells in a few OSs and it
JCF: does seem to vary.  bash takes the EXIT trap.  real ksh does, pdksh doesn't.
JCF: Solaris and OpenServer sh do not.  By the plain language in man pages and
JCF: POLA, it seems to me that the shells that don't take the trap are buggy, but
JCF: they're widespread and probably not going to be fixed.  SUSv3 is amazingly
JCF: silent on the question.  Can you accomplish what you want by directly
JCF: trapping SIGINT also?

I have found that if I want the trap 0 after an INT, I must tell the INT
handler to 'exit' as well.

JCF: -Chap

When will people learn how to think!??  I long for the day to come when
software is purchased on the basis of technical merit and usefulness and not
on the basis of marketing bullsh*t.  And when is intelligence going to become
a prerequisite for survival?