Jeknins intercepts signals

# Jenkins "Execute shell" build step to see signals blocked by Jenkins and
# so not-caught by child processes, such as apparently SIGQUIT (3).
# Note this may behave slightly differently in different system shells -
# e.g. bash did not block SIGINT (2) for me, but dash and ksh did.
# You may want a shebang on top for deterministic behavior of a specific
# shell, rather than current build agent's /bin/sh implementation.
RES=0

for SIG in 1 2 3 15 ; do
    echo "SIG = $SIG"
    ( trap "echo 'Got hit by $SIG' >&2 ; exit 0 ;" $SIG
      sleep 5
      echo "ERROR: Did not get SIG = $SIG" >&2
      exit 1 ) &
    sleep 1
    kill -$SIG $! || RES=$?
    wait $! || RES=$?
done

exit $RES