(bash) Does the EXIT trap fire if/when bash is exited via a signal?

[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.

[Helmut Waitzmann]

Post by 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.
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
)