Master GNU Screen: Create, Detach, and Reattach Sessions on Remote Servers

Introduction

When working on a remote server, an unexpected network drop can abort important scripts or compilation jobs. GNU screen solves this by providing a virtual terminal manager that lets you create multiple independent sessions, detach them, and reattach later, keeping processes alive even after the SSH connection closes.

Core Concepts: Session and Window

Session (Session) – Created when you run screen. It is a container that persists independently of your terminal, allowing processes to continue after disconnection.

Window (Window) – Within a session you can open several windows, each acting like a separate shell, similar to browser tabs, enabling easy task switching.

Creating a New Screen Session

The basic command is simply screen, but for clarity you should name the session using the -S option: dave@gitlab-runner:~$ screen -S compiler This creates a session named compiler. The session runs in the background while the terminal appears unchanged.

Detaching (Detach) the Current Session

To let a task continue after you leave, detach the session with the shortcut Ctrl+a d: [detached from 202352.compiler] The session remains active on the server.

Listing All Running Sessions

After reconnecting, use one of the following commands to see existing sessions: screen -ls or screen -list Example output:

dave@gitlab-runner:~$ screen -ls
There are screens on:
	202352.compiler	(08/18/25 15:30:00)	(Detached)
	201098.pts-0.gitlab-runner	(08/18/25 12:51:32)	(Detached)
2 Sockets in /run/screen/S-dave.

The compiler session is shown as Detached.

Reattaching (Reattach) an Existing Session

To return to a detached session, use: screen -r [session_name_or_pid] For example: dave@gitlab-runner:~$ screen -r compiler If only one detached session exists, screen -r without arguments works as well.

Managing Windows Inside a Session

All window‑related shortcuts start with Ctrl+a: Ctrl+a c – Create a new window. Ctrl+a " – Show a list of windows for selection. Ctrl+a n – Switch to the next window. Ctrl+a p – Switch to the previous window. Ctrl+a A – Rename the current window.

Terminating a Screen Session

Inside the session, type exit in each window; when the last window closes, the session ends.

From outside, send a quit command with the -X option:

dave@gitlab-runner:~$ screen -S compiler -X quit

UML Flowchart: Common Screen Operations

Visual representations of the workflow:

Conclusion

Although screen offers many options, mastering three core commands— screen -S (create), screen -ls (list), and screen -r (reattach)—combined with the Ctrl+a d shortcut for detaching, solves the majority of everyday use cases. This makes screen a reliable “save point” for long‑running tasks on Linux servers, allowing you to work without fearing network interruptions.