How to use the command "wall" (with examples)

The “wall” command is used to write a message on the terminals of users who are currently logged in. It allows users to send important system-wide announcements or messages to multiple users simultaneously.

Use case 1: Send a message

Code:

wall message

Motivation: Sending a message using the “wall” command is useful when you want to broadcast a message to all the users currently logged in on the system. For example, you can use it to announce a server maintenance window or inform users about an upcoming event.

Explanation: In this use case, the command “wall” is followed by the message that you want to send to all the users. This message will be displayed on the terminals of all logged-in users.

Example output:

Broadcast message from user@hostname
(/dev/pts/0) at 12:34 PM:

This is an important message for all users.
Please take note of the following information.

Use case 2: Send a message to users that belong to a specific group

Code:

wall --group group_name message

Motivation: Sometimes, you may want to send a message to users who belong to a specific group. This can be useful when you want to notify a particular team or department about a specific announcement or event.

Explanation: In this use case, the command “wall” is followed by the “–group” flag, which specifies the group to which the users belong. You need to replace “group_name” with the actual name of the group. After that, you provide the message that you want to send to the specified group of users.

Example output:

Broadcast message from user@hostname
(/dev/pts/0) at 12:34 PM:

This is an important message for all users in the "group_name" group.
Please take note of the following information.

Use case 3: Send a message from a file

Code:

wall file

Motivation: The ability to send a message from a file can be helpful when you have a longer or more complex message that you want to send to all users. Instead of typing the entire message in the command, you can prepare it in a separate file and pass the file as an argument to the “wall” command.

Explanation: In this use case, the command “wall” is followed by the name of the file from which you want to send the message. The content of the file will be displayed on the terminals of all logged-in users.

Example output:

Broadcast message from user@hostname
(/dev/pts/0) at 12:34 PM:

This is an important message for all users.
Please take note of the following information.

Use case 4: Send a message with timeout (default 300)

Code:

wall --timeout seconds file

Motivation: The “wall” command allows you to specify a timeout for displaying the message on the terminals of the users. This can be useful when you want to ensure that the message stays on the screen for a specific duration before disappearing.

Explanation: In this use case, the command “wall” is followed by the “–timeout” flag, which is used to specify the duration in seconds for which the message will be displayed. You need to replace “seconds” with the actual timeout duration. After that, you provide the name of the file containing the message.

Example output:

Broadcast message from user@hostname
(/dev/pts/0) at 12:34 PM:

This is an important message for all users.
Please take note of the following information.

Conclusion:

The “wall” command is a powerful tool for sending messages to multiple users who are currently logged in. With its various options, such as sending messages to specific groups and specifying timeouts, it provides flexibility and efficiency in system-wide communication.