The wall command can be used to send a message to other Terminals. In this example, John Doe sends the message Hello World to every other Terminal.

[john.doe@server1 ~]# wall "Hello World"
Broadcast message from john.doe@example.com (pts/0) (Tue May 9 13:12:56 2017):

Hello World

If Jane Doe is signed into the system, Jane will receive the message in her Terminal.

[jane.doe@server1 ~]#
Broadcast message from john.doe@example.com (pts/0) (Tue May 9 13:12:56 2017):

Hello World

Send the contents of a file

The contents of a file can be sent to every other Terminal. For example, let's say /home/john.doe/example.file contain the test How are you today.

[john.doe@server1 ~]# wall example.file
Broadcast message from john.doe@example.com (pts/0) (Tue May 9 13:12:56 2017):

How are you today

Change default message

By default, the first line of the wall message will begin with Broadcast message from. The -n option can be used to change this to begin with Remote broadcast message. This will also remove the from sender@domain.com from the message.

[john.doe@server1 ~]# wall -n "Hello World"
Remote broadcast message (Tue May 9 13:12:56 2017):

Hello World