# MUTEX
echo -n ">>> Locking: " >&2
if mkdir "${LOCKDIR}"; then
    # lock succeeded
    echo "$$" >"${PIDFILE}"
    trap 'rm -rf "${LOCKDIR}"' 0
    trap trap 'exit ${ENO_RECVSIG}' 1 2 3 15
    echo "success, installed signal handlers"
else
    # lock failed
    OTHERPID="$(cat "${PIDFILE}")"
    echo "lock failed, PID ${OTHERPID} is active" >&2
    exit ${ENO_LOCKFAIL}
fi
# /MUTEX