#!/bin/sh
# My current understanding about
# how to clean up temp files in POSIX shell.
# (NB: mktemp is reasonably portable… yet not POSIX)

tmpfile=$(mktemp)
echo "Creating temporary file ${tmpfile}…"
>"$tmpfile"
if test -f "$tmpfile"; then
	echo "… ok"
else
	echo "… problem, stopping"
	exit 1
fi

cleanup () {
	echo "removing $tmpfile" >&2
	rm "$tmpfile"
}

# cleaning up when the script exits normally
trap cleanup EXIT

# cleaning up when the script receives a termination signal,
# and killing itself with the same signal.
# * HUP = hangup
# * INT = user interrupt (^C)
# * TERM = normal termination signal
# Not included:
# * QUIT, which is the user interrupt (^\) used for debugging,
#   so we want to keep the temp file
# * PIPE (write on a pipe that no one reads) : I'm not sure
#   what to do yet
# * others?
# NB: it seems that this signal format is the only POSIX-compliant
#     one for both trap and kill
for signal in HUP INT TERM; do
	trap "cleanup; trap - $signal; kill -s $signal $$" $signal
done

echo "Here are the traps that were set:"
trap

while :; do
	echo "coucou" | tee -a "$tmpfile"
	sleep 1
done

echo "This will never get printed"