How to use the Linux Screen Command

Introduction

Before we begin talking about how to use the Linux Screen command, let's briefly understand - What is a Screen Command?

Using Linux Screen command, you can launch and use many shell sessions with a single ssh session. You can detach from a session and can reattach later. After you detach, the process you started earlier will still be running and managed by the screen itself. When you re-attach the process later, you will get the terminals the way you left them earlier.

In this tutorial, you will use the Linux Screen command. We will also address a few FAQs on how to use the Linux Screen command.

What's the Syntax of the screen Command

screen [-opts] [cmd [args]]

Options

-a: Force all capabilities into each window's termcap.

-A-[r|R]: Adapt all windows to the new display width and height.

-c file: Reads configuration file instead of .screenrc.

-d (-r): It detaches the screen running elsewhere (reattach here).

-dmS name: Starts as daemon: screen session in detached mode.

-D -RR: It does whatever is required to get a screen session.

-e xy: Changes the command characters

-f: Makes the flow control on, -fn=off, -fa=auto.

-h lines: Sets the size of scrollback history buffer.

-i: Interrupts the output sooner when flow control is on.

-L: Makes the login mode on.

-m: Ignores $STY variable, creates a new screen session.

-O: Chooses optimal output rather than exact vt100 emulation.

-p window: Preselect the named window  if it exists.

-q: Exits with non-zero return code when unsuccessful.

-Q: Command sends the response to the stdout of the querying process.

-r [session]: It reattaches to the detached screen process.

-R: It reattaches if possible, otherwise starts a new session.

-S sockname: Names the session .sockname.

-t title: It sets the title.

-T term: It uses term as $TERM for windows.

-U: It tells the screen to use UTF-8 encoding.

-v: It prints screen version.

-x: It attaches to the not detached screen.

-X: It executes as a screen command in the specific session.

Install Linux GNU Screen

Nowadays, the screen package is pre-installed on most Linux distros. Verify if it is installed on your system using the following command:

screen --version

If screen is not installed, use the following set of commands:

sudo apt update
sudo apt install screen

For CentOS and Fedora:

sudo yum install screen

Start Linux Screen

You need to simply type screen to start the screen session:

screen

Now, open a screen session, create a new window and start shell in that window.

You can get a list of commands using the following command:

Ctrl+a ?

Start Named Session

If you want to run multiple screen sessions, you can utilize named sessions. Run the following command to create a named session:

screen -S session_name

It is recommended to choose a descriptive session name.

Detach from Linux Screen Session

Run the following command to detach from the screen session:

Ctrl+l+a d

The program will keep running in the screen session after you detach from the session.

Reattach to a Linux Screen

Use the following command to resume the screen session:

screen -r

You need to append the r switch if you want to have multiple screen sessions running on your machine.

You can find the session ID using the following command:

screen -ls

Output

There are screens on:
    10835.pts-0.linuxize-desktop   (Detached)
    10366.pts-0.linuxize-desktop   (Detached)
2 Sockets in /run/screens/S-linuxize.

To restore the screen 10835.pts-0, type the following command:

screen -r 10835

Customize Linux Screen

It is possible to modify the default screen settings using the .screenrc file. Check the below sample ~/.screenrc configuration:

# Turn off the welcome message
startup_message off

# Disable visual bell
vbell off

# Set scrollback buffer to 10000
defscrollback 10000

# Customize the status line
hardstatus alwayslastline
hardstatus string '%{= kG}[ %{G}%H %{g}][%= %{= kw}%?%-Lw%?%{r}(%{W}%n*%f%t%?(%u)%?%{r})%{w}%?%+Lw%?%?%= %{g}][%{B} %m-%d %{W}%c %{g}]'

Linux Screen Usage

Below are the basic steps to get started with screen:

1. Type screen on the command prompt.
2. Run the required program.
3. Use the key sequence Ctrl-a + Ctrl-d to detach from the screen session.
4. Reattach to the screen session using screen -r.

FAQs to Use the Linux Screen Command

Conclusion

We hope this detailed guide helped you understand how to use the screen command.

If you have any queries, please leave a comment below, and we’ll be happy to respond to them for sure.