FreeBSD >Sending a Message to All Users on a System

You can use the wall command to send a message to every user on a system. General syntax of wall command is as follows:
wall
Message
Message
...
....
..
When the message is complete, press Control-D.

1) To display message "Disk failure system will be down for 30 minute" to all users use wall as follows:
# wall
Disk failure system will be down for 30 minute
--UNIX Admin
--MyCorp.com


When the message is complete, press Control-D (CTRL+D) to send message to all user.

2) To display message "Web server under DOS attack, come to IDC # 3" to all WHEEL group member use wall command with –g option as follows:
# wall –g wheel
Web server under DOS attack, come to IDC # 3 to investigate matter further.
-- IT HEAD

When the message is complete, press Control-D (CTRL+D) to send message to all user.