Send message to all linux users

Linux for freshers

Wall displays the contents of a file or, by default, its standard input, on the terminals of all currently logged-in users. The command will cut over 79 character long lines to new lines. Short lines are white space padded to have 79 characters. The command will always put the carriage return and new line at the end of each line.

Only the super-user can write on the terminals of users who have chosen to deny messages or are using a program that automatically denies messages.

Reading from a file is refused when the invoker is not a superuser and the program is suid or sgid.

Usually, system administrators send messages to announce maintenance and ask users to log out and close all open programs. The messages are shown to all logged-in users with a terminal open.

wall [-n] [-t timeout] [message | file]

The most straightforward way to broadcast a message is to invoke the wall command with the message as the argument:

wall «The system will be restarted in 10 minutes.»

Broadcast message fromroot@linuxforfreshers (pts/0) (Mon Jan 4 13:22:07 2021):

The system will be restarted in 10 minutes.

The message will be broadcasted to all users that are currently logged in.

To suppress the banner and show only the text you types to the logged-in users, invoke the command with the -n (—nobanner) option:

wall -n «The system will be restarted in 10 minutes.»

The system will be restarted in 10 minutes.

If you want to write multi-line messages, invoke the command without an argument:

The wall command will wait for you to enter text. When you’re done typing the message, press Ctrl+D to end the program and broadcast the message.

You can also use the here-string redirection or pipe the output of another command to wall. Here is an example showing how to use the echo command to broadcast multi-line messages:

echo «The system will be restarted in 10 minutes. \nPlease save your work.» | wall

Broadcast Message from root@linuxforfreshers

The system will be restarted in 10 minutes. \nPlease save your work.

Broadcasting a Message From a File

If you are regularly sending the same messages, you can write each one of them to a file, so that you don’t need to re-type the same text. wall reads from the file only when invoked as root.

To broadcast the contents of a file, invoke the wall command followed by the file name:

The system will be restarted in 10 minutes.

Broadcast message from root@linuxforfreshers (pts/0) (Mon Jan 4 13:30:07 2021):

The system will be restarted in 10 minutes.

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Wall Command in Linux with Examples

In a Linux environment, there are scenarios when multiple users are working on the server simultaneously through SSH. However, sometimes system admin needs to restart or shut down the system due to e.g. system maintenance, kernel upgrade, adding or removing hardware from the server. If this is the case, the system admin should inform all logged-in users to save their work. Email does not fit in this situation, as you first have to find out who is logged in and then sending emails to them. Also, you do not know when the user will read the email. Luckily, there is a Linux command “wall” that allows you to do this easily.

Here, we are going to describe the usage of wall command in Linux. Remember, the wall command works the same for all Linux distributions.

Note: Wall command only displays the message on the Terminal window of logged-in users. Users working only on GUI, with no Terminal window open will not be able to see the messages.

Linux Wall Command

Linux Wall command allows you to send a message or the contents of a file to all the currently logged-in users. If no file or message is specified, wall command reads the message from the stdin (standard input).

Wall Command Syntax

The syntax for wall command is as follows:

Send a Message to All Users

To send a message to all the currently logged-in users, type wall followed by the message you want to send.

This command will send the message to all the logged-in users with a Terminal window open.

Note: For some Linux distributions, you have to execute the above command as super user. Also, if a user has chosen to deny messages to their Terminals (like using the mesg command), then only a sudo user will be able to send messages to their Terminals.

Following are the outputs displayed to two users “linuxways” and “ummara” who are logged-in to the server via SSH. These users are working from the system running Ubuntu and Debian.


The wall command also reads the message from stdin (standard input). To do so, simply type wall and hit Enter.

After that, type any message or messages you want to send to logged-in users. Once you are done typing the messages, press Ctrl+D to send those messages.

Here is the output which all logged-in users received on their Terminal.

Send a Message from a File

If there are some messages that you have to repeat often, you can simply type them in a file. When you have to send those messages to the logged-in users, simply call that file with wall command. Remember, you will require sudo privileges if you want to send a message from a file.

For example in the following output, file content has been first shown using the cat command. Then to send the message contained in the file, the filename is passed to the wall command.

These are the outputs (from the file msg.txt) received by the logged-in users.

Send a Message to a Group

Instead of sending the message to all logged-in users, you can send it to only the members of a group who are currently logged in to your system. The syntax is as follows:

For example, to send a message to a group named “sshusers”, the command would be:

All the members of the “sshusers” group who are currently logged in to the server will receive the specified message.

Suppress Banner

The wall command displays a banner before displaying a message as can be seen in the following screenshot.

To suppress this banner, use the -n option with the wall command:

For example, the following command will only display the specified message while suppressing the banner.

All the logged-in Terminal users will receive the message without a banner.

View Version Information

To view the version of the wall command, use the following command:

The following output shows the version of the wall utility is 2.34.

Wall is a handy utility that helps a multi-user system admin to quickly notify other users to save their work before a system shutdown or reboots. In this article, we covered how to use the wall command to communicate with logged-in users. Hope you find it interesting and useful.

About the author

LinuxWays Team

We create HowTos and Tutorials for Sys Admins. Visit us on LinuxWays.net

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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:

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".

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

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

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

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:

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.

Conclusion

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.

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How to Send a Message to Logged Users in Linux Terminal

How can I send a messages to logged on users in a Linux server? If you are asking this question, then this guide will help you learn how to do that. We will demonstrate how to send a message to all or a specific logged on user, on the terminal in Linux.

Linux offers a variety of means for sending messages to users logged on to a server as explained in the two methods below.

In the first method, we will use wall command – write a message to all currently logged in users on the terminal as shown.

# wall "System will go down for 2 hours maintenance at 13:00 PM"

To disable the normal banner printed by wall, for example:

Broadcast message from [email protected] (pts/2) (Sat Dec 9 13:27:24 2017):

Add the -n (Suppress the banner) flag, this however, can only be used by the root user.

# wall -n "System will go down for 2 hours maintenance at 13:00 PM"

In the second method, we will use write command, which comes pre-installed on all if not most Linux distributions. It allows you to send a message to another user in the terminal using tty.

First check the all logged on users with the who command as shown.

There are currently two users are active on the system (tecmint and root), now the user aaronkilik is sending a message to the root user.

$ write root pts/2 #press Ctrl+D after typing the message.

That’s all! Do share with us other methods or commands for sending messages to all logged on users through the terminal in Linux. If you have any queries, please use the feedback form below.

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