gazelle@shell.xmission.com (Kenny McCormack):
Note: This thread is entirely about bash. No other shells or "POSIX" are relevant here. But comparisons between various versions of bash may be relevant, since I think the behavior may have changed over the versions.
That said, suppose I have something like:
trap 'date > /tmp/somefile' EXIT
# Rest of script
Now, if during "Rest of script", say I hit ^C. Or ^\. Or, say I send a signal via "kill" from another terminal. Does my exit trap get executed?
I've had varying results. I am pretty sure that at one point, the answer
was "no", but recently, I've noticed that when I exit via ^C, the EXIT trap does execute. I'm curious what the "official" answer is.
The "official" answer should be in the "bash" documentation, but
anyone who would like to investigate it, might let "bash" run the
following script ("the_script")
#!/bin/sh
trap_command()
{
cat <<EOF
printf 'Executing %s trap at ' ${1:?} &&
date -- '+%F %T'
EOF
}
command="$( trap_command EXIT )" &&
trap "$command" EXIT &&
for signal
do
(
sleep -- 1 &&
printf 'Sending signal %s at ' "$signal" &&
date -- '+%F %T' &&
kill -s "$signal" -- "$$"
) &
sleep -- 3
done
providing signal names as parameters and observe what the shell
will do, for example
(
for signal in INT QUIT HUP TERM
do
bash ./the_script "$signal"
printf 'Script exited returning status %s\n' "$?"
done
)
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