busybox/shell/ash_test/ash-signals/signal3.tests

#!/bin/sh

$THIS_SH -c '
hup() {
    echo "child got HUP"
}
trap hup HUP
echo "child sleeps"
sleep 1
echo "child exits"
' &

child=$!
sleep 0.1 # let child install handler first
kill -HUP $child
wait
echo "parent exits"