The “screen” Command in Linux [13 Practical Examples]

The screen command in Linux is used to run multiple sessions in a single terminal. For instance, you are working on a server remotely and you have only one terminal. But you want to run multiple processes simultaneously. The screen command makes it possible. Moreover, it minimizes the chances of abruptly closing a task midway that might be sensitive or takes a lot of time to complete. In this article, I will show you the usage of the screen command in Linux with several practical examples as simple as possible.

A. Description

The screen command in Linux comes by default in most Linux Distributions. The command was developed so that a user can run a process even though he is not connected to the terminal. Oliver Laumann and Carsten Bormann designed it first for Unix and published it in 1987. The command gained a lot of popularity later and went through a lot of changes. The screen command in Linux is particularly important for SSH(Secure Shell) sessions. A remote server user can run multiple processes on a single terminal by using the screen command.

B. Syntax

The syntax of the screen command in Linux is simple and it goes like the following:

screen [OPTION]... [COMMAND [ARGUMENT]]...

Note: The OPTION and ARGUMENT enclosed by square brackets and followed by three dots denote you can provide multiple options and arguments at the same time. Moreover, the COMMAND denotes that you can execute a command in a session without attaching it.

C. Options

The screen command in Linux has a  lot of options and you can check them yourself by writing the following command in the command prompt:

man screen

Useful Options

  • -S, creates a new session.
  • -p, is used to assign a password to a session.
  • -X, executes commands inside a session.
  • -r, is used to reattach to a session.
  • -ls, lists out all the running sessions.
Note: The options in Linux CLI(Command Line Interface) are all case-sensitive. Writing the same option in a different case might execute different tasks or generate an error.

How to Install the “screen” Command in Linux

Most of the time, the screen command in Linux comes by default. However, if your Linux Distro doesn’t contain this command, you can install it by following the steps below:

Steps to Follow >

❶ Launch a Terminal in your Ubuntu.

❷ Copy the following command in the command prompt and hit ENTER:

sudo apt-get install screen

The installation process will be started. You will see an output like below.Installing the screen command in Linux

❸ Write “Y” if the see the message “Do you want to continue” and press the ENTER button again.

Your installation will be completed within a very short time.Showing "Do you want to continue" Message

Practical Examples of the “screen” Command in Linux

In this section, I will try to cover some basic usage and features of the screen command in Linux. I explained everything step-by-step. Follow everything with me to get the full effect.

Example 1: Create a Session Using the “screen” Command in Linux

Firstly, I will show you how I can start a session only using the screen command in Linux. The steps are simple. Follow them below:

Steps to Follow >

❶ At first, launch the Ubuntu Terminal.

❷ Write the following command in the Terminal:

screen

❸ Press the ENTER button from the keyboard.

Output >

In the first image, I only type the screen command, nothing else. And pressed ENTER.Typing the screen comamand in LinuxYou might feel like everything on the terminal has disappeared for some reason. However, it is not the case. Actually, you have started a new terminal session!New screen sessionIn addition, if you ever get an output like this, just keep on pressing the Space button.Showing the version of the screen command in Linux and its copyright


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Example 2: Screen Detaching

In the previous example, you have learned how to start a new session. Now, I will show you how to detach without ending it. Now do the following:

Steps to Follow >

❶ Press CTRL + ALT + T to open an Ubuntu Terminal.

❷ Copy the following command in the command prompt to start a new session:

screen

❸ Hold the CTRL button, press A and then D.

Output >

When you detach from a session, you will return back to your old session. Also, you will see a message “[ detached from …..]” like below.Detaching a screen

Example 3: Create a Named Session Using the “screen” Command in Linux

This time I will create a named session. Named sessions help you to keep track of all the sessions running on a machine. Also, it makes reattaching easier. To name your session, follow the steps below:

Steps to Follow >

➊ Go to your Ubuntu and launch a Terminal.

➋ Insert the command below in the Terminal:

screen -S newsession
Note: Here “newsession” is the name of my terminal session.

➌ Then hit the ENTER key.

Output >

You should remember that creating a named session doesn’t mean the title of your Terminal will be different or anything. You won’t see any difference. However, it will help you later.Creating a named screen session using the screen command in LinuxAs you can see, the new session looks exactly similar to Example 1.New screen session

Example 4: List of Screens Using the “screen” Command in Linux

Let’s say there are a lot of sessions running in my system and I want to have a list of them. Thankfully, the screen command in Linux comes with an option (“-ls”) to list all the sessions. Do the following to see your list:

Steps to Follow >

❶ Open a Terminal from your Ubuntu.

❷ Type the following command in the command prompt:

screen -ls

❸ Hit ENTER from your keyboard.

Output >

Currently, there are two terminal sessions running on my machine. You can see a number followed by a string in the list. The number denotes PID (Process Identification Number) and the string is the name of that process. You will see “Attached” or “Detached” on the right side of the list. “Attached” denotes you are in that session right now and “Detached” is the opposite.Lising all the available screen using the screen command in Linux

Example 5: Screen Reattaching

Now I will reattach to a session that I detached earlier. The screen command in Linux has an option “-r” for that purpose. You also need to provide an argument which can be the name of the session or PID (process identification number). Now do the following:

Steps to Follow >

❶ Launch an Ubuntu Terminal by pressing CTRL + ALT + T.

❷ Write the command below in the Terminal:

screen -r newsession

OR,

screen -r 2477

❸ Find the ENTER button on your keyboard and press it.

Output >

At first, I reattached an existing session by its name. Then I detached from it and reattached it again using the PID.Reattaching to a screen using name and PID

Example 6: Kill a Screen Using the “screen” Command in Linux

Linux has a dedicated command to end any process which is the kill command. You can use this command to end a terminal session as well. But you need the PID of a process for that. In the image below, the PID of newsession is 2090. Write the following command to find the PID of your screens:

screen -ls

Finding PID a screen using the screen command in LinuxNow follow the steps below:
Steps to Follow >

❶ Go to your Ubuntu and open a Terminal.

❷ Copy the following command in the command prompt:

kill 2090

❸ Hit the ENTER key.

Output >

To show you that the process is killed, I used the “screen -ls” command. And see, it is showing “No Sockets found” which indicates there is no session running in your Ubuntu.Killing a screen

Note: I used the following command to list all the available screens:

screen -ls

Example 7: Terminate a Screen by Name

It is also possible to terminate a session by name using the screen command in Linux. For your information, you can end your session by typing “quit” too. But you need to be in the session for this. Now I will show you how to kill a session when you are detached. For that, I will use the “-Xoption for that purpose. The “-Xoption of the screen command in Linux can execute a command in a detached screen session. To find the name of your screens, type the following command in the command prompt:

screen -ls

Listing available screen using the kill command in LinuxIn the above photo, there is a screen session named newsession. To terminate it, do the following:

Steps to Follow >

❶ At first, launch a Terminal from Ubuntu.

❷ Insert the command in that Terminal:

screen -X -S newsession quit

❸ Press the ENTER key.

Output >

Here, I executed the “quit” command in the detached newsession. As a result, it is terminated now. That’s why when I listed out the current running screen session, the output is “No Sockets found”.Quitting a session by name

Note: I copied the command below to see all the screens on my machine:

screen -ls

Example 8: Run a Process in the Background Using the “screen” Command in Linux

You have everything you need. Now let’s run a process in the background. Because you will use the screen command in Linux for this purpose mostly, For demonstration, I will upgrade my system this time. Now follow all the steps below with me:

Steps to Follow >

❶ Open an Ubuntu Terminal first.

❷ Write the following command to start a new screen session:

screen -S newsession

❸ Then, copy the command below to upgrade your system:

sudo apt-get upgrade

❹ Hold the CTRL button, then press A and D to detach the screen.

❺ To check the condition of the upgradation, insert the command below in Terminal:

screen -r newsession

➏ Finally, press the ENTER button.

Output >

I have attached a couple of photos to help you with the process. The first photo shows how I created a new terminal session and reattached it after detaching it.Creating and reattaching using the screen command in LinuxThis image shows the command to start the upgradation process.Upgrading the systemFinally, this image shows what I found after reattaching. See, the process was still running in the background.Showing the upgrading process is still running in the background


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Example 9: Renaming a Screen

In this example, I will show you how to rename an existing screen session. For instance, I have a session named oldsession and I want to rename it to newsesssion. You need both the name and PID of a session to do that. To view the name of your screens, insert the command below:

screen -ls

Showing the name of the sessions using the screen command in LinuxNow follow the steps below to rename a screen session:

Steps to Follow >

❶ Firstly, open a Terminal in Ubuntu by pressing CTRL + ALT + T from the keyboard.

❷ Copy the following command in the command prompt:

screen -S 3135.oldsession -X sessionname newsession
Note: If you use only name or PID, renaming won’t work.

❸ Find the ENTER button on your keyboard and hit it.

❹ To check whether the name has changed, write the following command and press ENTER:

screen -ls

Output >

Now see, the session name has changed. I can be sure of that because the PID is the same.Changing the name of a session using the screen command in Linux

Example 10: Add Password in the “screen” Command in Linux

You may require it to run a process securely. The screen command in Linux provides an option to assign a password to a session. The option is “-p” and your password should be the value. Moreover, you also need to use option “-S”. Now do the following:

Steps to Follow >

❶ Firstly, launch a Terminal in Ubuntu.

❷ Write the following command in the Terminal:

screen -S newsession -p 123456

❸ Press the ENTER key.

Output >

Here I have created a screen session named newsession and the password is 123456. When I tried to reattach to that screen, it was asking for a password.Creating a session with password

Note: The following command is used to reattach to the session:

screen -r newsession

Example 11: Split the Screen Horizontally

If you are a Windows or MacOS user, splitting the screen is a regular thing for you. However, in Linux splitting is not that easy. Luckily, the screen command in Linux has made it easy for us. You can divide your screen by pressing some keys from the keyboard. To split your screen horizontally, do the following:

Steps to Follow >

❶ Open an Ubuntu Terminal firstly.

❷ Copy the following command in the command prompt to start a session and hit ENTER:

screen -S newsession

❸ Press CTRL + A, followed by CTRL + S.

Output >

See, the screen is divided into half from the middle. I will show you later how to go to the other half and write something.Splitting screen vertically

Example 12: Split the Screen Vertically

Now I will show you how to split the screen vertically in the screen command in Linux. Now follow the steps below with me:

Steps to Follow >

❶ Launch a Terminal from your Ubuntu.

❷ Insert the following command in the command prompt to start a session and hit ENTER:

screen -S newsession

❸ Press CTRL + A, then the “|” sign (the vertical bar).

Output >

In the output, there is a vertical white line in the middle. That means the screen is split.Spilling image horizontally

Example 13: Switch Between Tabs and Create New Window

In Example 11 and Example 12, you have learned how to split a screen. Now you will learn to switch between those tabs and create a window to write something. I will take the screen of Example 12 for this example. Now follow the steps with me:

Steps to Follow >

❶ Firstly, go to your Ubuntu and open a Terminal.

❷ Type the following command to create a session:

screen -S newsession

❸ Split the screen vertically by pressing CTRL + A, then “|” ( the vertical bar).

❹ Press CTRL + A, then the Tab button to go to another tab.

❺ Again, press CTRL + A and CTRL + C to create a new window.

Output >

Here, I followed step 4 to go to the tab on the right. You can see the cursor there.Switching tab Then step 5 to create a window. Now the right tab also has “walid@Ubuntu” at the beginning. Now I can write commands on that tab as well.Creating new window

Conclusion

The screen command in Linux is a very useful command if you are accessing a server from a remote location. It will remove some hassle, make you more efficient and productive. I hope this article has helped you to grasp the screen command in Linux. Make sure you have practiced every example and followed every step.


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Walid Al Asad

Hello Everyone! I am Walid Al Asad. Currently, I am working at a tech company named Softeko as a Linux Content Developer Executive. I live in Dhaka, Bangladesh. I have completed my BSc. in Mechanical Engineering from Bangladesh University of Engineering and Technology (BUET). You can find me on LinkedIn, and ResearchGate. Read Full Bio

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