Mailinglist Archive: opensuse (3378 mails)

[Keith Winston <kwinston@xxxxxxxxxxx>]

For all you shell programmers out there, I ran across what I think is a
bug in bash using traps.  I wrote a script to trap signal 1 (SIGHUP) to
make it behave like a daemon (reread a config file).  If you trap exit,
signal 0 AFTER trapping signal 1, the trap on signal 1 no longer works
and the process is killed.  For example,

conf=~/daemon.conf
tempfile=/tmp/DAEMON_$$
trap 'work=`cat $conf`' 1
trap 'rm -f $tempfile; exit' 0 15

Then, if you run the process and send signal 1, it dies.
If you reverse the order of the trap statements...

trap trap 'rm -f $tempfile; exit' 0 15
trap 'work=`cat $conf`' 1

Now, it works correctly, signal 1 is trapped and the process continues
running.

I originally posted this on comp.unix.shell and the bug was confirmed on
Solaris and RH.  It has since been posted to gnu.bash.bug and awaiting a
reply.  In the meantime, the work around seems to be to trap signal 0
first.

Best Regards,
Keith
-- 
LPIC-2, MCSE, N+
I can C for miles and miles
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