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wall – Output Information to All Currently Open Terminals on the System

The wall command is a Linux utility that allows users to broadcast messages to all currently logged-in users on a system. It sends the message to every open terminal on the system, including both physical terminals and terminal emulators. The wall command is useful for sending important announcements or notifications to all users at once.

Overview

The wall command is easy to use. Simply type wall followed by the message you want to send. The message can be typed directly into the command line, or it can be piped in from another command. For example, the following command sends a message to all users on the system:

$ wall "The system will be going down for maintenance in 15 minutes."

This will send the message “The system will be going down for maintenance in 15 minutes.” to all currently logged-in users.

The wall command can also be used to send messages from a file. To do this, use the input redirection operator (<) to specify the file that contains the message. For example:

$ wall < message.txt

This will send the contents of the message.txt file to all users on the system.

Options

The wall command has several options that can be used to modify its behavior. The following table lists all available options:

Option Description
-n Do not prepend the message with the sender’s username.
-t Timeout in seconds after which the message will be sent.
-g Send the message to all users in the specified group.
-u Send the message only to the specified user.

Troubleshooting Tips

If the wall command is not working as expected, there are a few things you can check:

  • Make sure you have permission to send messages to other users. Only users with root privileges can send messages to users who are not logged in as root.
  • Check that the message is being formatted correctly. The wall command expects the message to be enclosed in quotes.
  • If you are sending a message from a file, make sure the file exists and is readable by the user running the wall command.

Notes

  • The wall command can be used in conjunction with other commands to create more complex messages. For example, you can use the echo command to create a message and then pipe it into the wall command.
  • Be careful when using the wall command, as it can be disruptive to other users. Only use it for important announcements or notifications.

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