Plan 9 from Bell Labs’s /usr/web/sources/contrib/nemo/rc/bin/msgs
#!/bin/rc echo msgs >/dev/label >[2]/dev/null test -e /who/$user/msgs || { cp /dev/null /who/$user/msgs chmod a+w /who/$user/msgs chmod +a /who/$user/msgs } date >/who/$user/msgs echo scroll >/dev/wctl >[2]/dev/null exec tail -1 -f /who/$user/msgs