Sending a message to logged in users in Bash
This article explores methods to send data to another logged in user in Bash. This article discusses methods to find active users and send them messages.
Finding Online Users in Bash
Before sending data to an online user, you must verify whether the user is online. You can use any of the following commands to get the online users of the system.
- w Command: Shows who is logged in and what they are doing.
- id with the -un flag: When used with the -u and -n flags, the id command displays the effective user name.
- who with the a flag: Displays all logged-in users.
To demonstrate, let's look at who -athe output of the command.
root@abdullah:/home/abdullah# abdullah
pts/0 2022-01-08 12:56 (:0.0)
root@abdullah:/home/abdullah# root
pts/1 2022-01-08 12:56 (:0.0)
pts/0 is a special file for the first terminal (the second output line). Data written to this console will be displayed on the first terminal.
For more information on the above command, use the following command.
man w
man id
man who
A man page (short for man pages) is a Unix utility that displays information about system calls, library calls, formal standards and conventions, and even abstract concepts. Since man pages are downloaded with the kernel, no internet connection is required.
Writing to Online Users Using Bash
Now that we've explored methods for finding logged-in users, we'll look at methods for sending them messages.
The commands below will show you how to send messages to online users through different terminals.
root@abdullah:/home/abdullah# write abdullah pts/0
The above command writes a message to user abdullah on console pts/0. After entering the above command, the terminal will ask you to provide a message prompt.
Type the message (let's say we type: Hello Abdullah) and press CTRL+Z to exit the prompt.
Now, if you see another terminal logged in as user abdullah, it will contain the following:
abdullah@abdullah:~$ Message from root@abdullah on pts/1 at 12:20...
abdullah@abdullah:~$ Hello Abdullah
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