Linux and Unix wall command
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Wall sends a message to everybody logged in with their mesg permission set to yes. The message can be given as an argument to wall, or it can be sent to wall's standard input. When using the standard input from a terminal, the message should be terminated with the EOF key (usually Control-D).
The length of the message is limited to 22 lines. For every invocation of wall a notifica tion will be written to syslog, with facility LOG_USER and level LOG_INFO.
wall [-n] [ message ]
| -n | Suppresses the normal banner printed by wall, changing it to "Remote broadcast message". This option is only available for root if wall is installed set-group-id, and is used by rpc.walld. |
Typing the above command from root would broadcast "there is hope" to all other users termial who are logged into the computer. Below is an example of what each terminal would show after the wall post.
Broadcast message from root (pts/1) (Thu May 23 08:28:21 2013):
there is hope
there is hope
