Thanks for the quick reply.
Unfortunately it made no difference putting #!/bin/bash
This works on every other system I've tried.
Message
From: redhat-list-bounces (AT) redhat (DOT) com
[mailto:redhat-list-bounces (AT) redhat (DOT) com] Behalf Miskell, Craig
Sent: 29 January 2007 00:07
To: General Red Hat Linux discussion list
Subject: RE: Simple bash problem.
Anyone know why the following simple bash script fails
on RHEL3 (fully patched)? It seems the "trap" command
is being silently ignored.
--
#!/bin/sh
sigtrap () {
echo "Caught signal!"
exit 0
}
trap sigtrap 1 2 3 15
while read X; do
echo $X
done
I'm not 100% sure, but I think it might be because of the #! Line. Bash
might be seeing that you've invoked with "/bin/sh", and is deciding to
operate in limited PSIX shell mode (sorry, the exact terminology for
that escapes me). Try #!/bin/bash and see how that goes,
Craig
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1/28/07, Simon Ashford <Simon.Ashford (AT) npl (DOT) co.ukwrote:

Thanks for the quick reply.

Unfortunately it made no difference putting #!/bin/bash

This works on every other system I've tried.

I just tested on RHEL3 and RHEL4 here. Worked as I guess you would
expect on RHEL4 but on RHEL3 the SIGQUIT was ignored. Looking in the
manpage I'm not sure I understand why it isn't being ignored in
RHEL4?!

John

1/28/07, inode0 <inode0 (AT) gmail (DOT) comwrote:
1/28/07, Simon Ashford <Simon.Ashford (AT) npl (DOT) co.ukwrote:

Thanks for the quick reply.

Unfortunately it made no difference putting #!/bin/bash

This works on every other system I've tried.

I just tested on RHEL3 and RHEL4 here. Worked as I guess you would
expect on RHEL4 but on RHEL3 the SIGQUIT was ignored. Looking in the
manpage I'm not sure I understand why it isn't being ignored in
RHEL4?!

Adding a "trap -p" to the script shows that none of the signals are
being trapped on RHEL3 by this script. Curious.

John

1/28/07, inode0 <inode0 (AT) gmail (DOT) comwrote:
1/28/07, inode0 <inode0 (AT) gmail (DOT) comwrote:
1/28/07, Simon Ashford <Simon.Ashford (AT) npl (DOT) co.ukwrote:

Thanks for the quick reply.

Unfortunately it made no difference putting #!/bin/bash

This works on every other system I've tried.

I just tested on RHEL3 and RHEL4 here. Worked as I guess you would
expect on RHEL4 but on RHEL3 the SIGQUIT was ignored. Looking in the
manpage I'm not sure I understand why it isn't being ignored in
RHEL4?!

Adding a "trap -p" to the script shows that none of the signals are
being trapped on RHEL3 by this script. Curious.

trap "sigtrap " 1 2 3 15

seems to get it to work on RHEL3 but this seems pretty buggy to me.

John

1/28/07, inode0 <inode0 (AT) gmail (DOT) comwrote:
1/28/07, inode0 <inode0 (AT) gmail (DOT) comwrote:
1/28/07, inode0 <inode0 (AT) gmail (DOT) comwrote:
1/28/07, Simon Ashford <Simon.Ashford (AT) npl (DOT) co.ukwrote:

Thanks for the quick reply.

Unfortunately it made no difference putting #!/bin/bash

This works on every other system I've tried.

I just tested on RHEL3 and RHEL4 here. Worked as I guess you would
expect on RHEL4 but on RHEL3 the SIGQUIT was ignored. Looking in the
manpage I'm not sure I understand why it isn't being ignored in
RHEL4?!

Adding a "trap -p" to the script shows that none of the signals are
being trapped on RHEL3 by this script. Curious.

trap "sigtrap " 1 2 3 15

seems to get it to work on RHEL3 but this seems pretty buggy to me.

, this is really my last followup to myself. Giving this a little
more thought leads me to observe that sigtrap is being caught as part
of your sigspec changing the name of your function to something
that isn't legal in the sigspec would probably be a good idea in any
event and then RHEL3 works as you expect.

John

inode0 wrote:

, this is really my last followup to myself. Giving this a little
more thought leads me to observe that sigtrap is being caught as part
of your sigspec changing the name of your function to something
that isn't legal in the sigspec would probably be a good idea in any
event and then RHEL3 works as you expect.

Reminds me of when I wrote a test shell script called "test" and
couldn't for the life of me get it to work correctly. :)