It's a rather archaic command: Code: $ write -h Usage: write [options] <user> [<ttyname>] Options: -V, --version output version information and exit -h, --help display this help and exit It's like a pipeline between different users' terminals! You can write stuff into a terminal in one X session, and copy it from a terminal in another; e.g. copy and paste between a main X session and a Xephyr window. Edit: or not. It seems that messages get permanently disabled on pts? Argh!