How to Use the wall Command in Linux

What is wall

wall ("write all") sends a message to the terminals of all users who are logged in. It is useful for warnings about maintenance, reboots or emergencies.

Syntax

wall [options] [message | file]

• options change how the command works.
• message is the text to send.
• file is a file that holds the text.

Common options

• -n hides the banner ("Broadcast message from ...").
• -t timeout sets the time in seconds to try to deliver the message. The default is 300 seconds.
• -g group sends only to users in a group.
• -V shows the version.
• -h shows the help.

Examples

Send a short message

wall "The system will undergo maintenance at 3 PM."

All logged-in users see a banner with your user name, host and time, then the message.

Send a message from a file

wall /path/to/message.txt

Send without the banner

wall -n "Please save your work."

The -n option is for the root user only.

Send to a group

wall -g developers "Deployment starts in 10 minutes."

Pipe the message

echo "Server restarts in 5 minutes" | wall

Notes

• Users with mesg n set do not receive messages from normal users. Messages from root are always shown.
• shutdown uses wall to warn users, for example sudo shutdown -r +10 "Rebooting for updates".
• Messages go to terminals and do not reach people who are not logged in.

Quick recap

• wall "text" sends a message to all logged-in users.