Home Linux Commandline Tips How to Send Broadcast Message to Logged-in Users on Linux Terminals

How to Send Broadcast Message to Logged-in Users on Linux Terminals

Linux is a multi-user operating system that allows multiple users to log in and use the system. This implies that at any given time, you might have several users logged in.

Sometimes, you might need to send a message or notification to all the users without necessarily placing a phone call or sending them emails. This is mostly when you want to announce a maintenance task or instruct them to log out.

In this guide, we will demonstrate how you can send messages to all logged-in users in the system. This only applies to users who are logged in via a terminal window using an SSH client such as PuTTY.

Send Messages to Logged-in Users Using the Wall Command

The wall command is a command-line utility that displays messages to all logged-in users on the terminal.

The wall command takes the following basic syntax:

$ wall OPTION { file | message }

If no file is specified, then the wall command reads the message from standard input and broadcasts it to all logged-in users.

For example, the following command reads the message enclosed in quotation marks as the argument and sends it to all logged-in users

# wall "The system will be shutting down at 1500HRS for maintenance. Apologies for any inconvenience caused".
Send Broadcast Message to Users in Terminal
Send Broadcast Messages to Users in Terminal

When viewed from a logged-in user (in this case bob), the message appears as shown on the terminal window.

Broadcast Message from Root
Broadcast Message from Root

To display a message from a file, invoke the wall command followed by the file name as shown.

$ wall sample_msg.txt
View Broadcast Message from File
View Broadcast Message from File

This is how the user receives the message on the terminal.

Broadcast Message To User
Broadcast Message To User

Send Messages to a Specific Logged-in User

Alternatively, you can use the write command to send a message to a specific user. To list all the currently logged-in users, invoke the who command:

$ who
Show Logged-In Users on Linux
Show Logged-In Users on Linux

For example, to send a message to a user called winnie and notify her about a system restarting in the next 3 hours, run the following write command with the echo command.

$ echo "This system will be restarted in 3 hours" | write winnie  

On the user’s terminal, the message will appear as shown.

Send Message to User in Terminal
Send a Message to the User in the Terminal

We have covered various ways of sending a message or notification to logged-in users using the wall and write commands. We hope that you can now send messages to logged-in users without a problem.

Winnie Ondara
My name is Winnie, a Linux enthusiast and passionate tech writer in Linux and DevOPs topics. I enjoy keeping abreast with the latest technologies in the Linux ecosystem and trying out new tools provided by the FOSS community.

Each tutorial at UbuntuMint is created by a team of experienced writers so that it meets our high-quality standards.

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