There was a time on some UNIXes where you could just write to other people's ttys, no write/wall needed, just echo >/dev/... Making write/wall sgid, and restri

There was a time on some UNIXes where you could just write to other people's ttys, no write/wall needed, just echo >/dev/... Making write/wall sgid, and restricting tty write access to that group, was a significant security upgrade back in the day.