Linux Shell Scripting Cookbook - Third Edition

Sending one message to one user

The write command will send a message to a single user:

    $ write USERNAME [device]

You can redirect a message from a file or an echo or write interactively. An interactive write is terminated with Ctrl-D.

The message can be directed to a specific session by appending the pseudo terminal identifier to the command:

    $ echo "Log off now. I'm rebooting the system" | write user1 pts/3