> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # GNU Screen > GNU Screen is a terminal multiplexer that allows managing multiple shell sessions within a single terminal. GNU Screen is a **terminal multiplexer** that lets you manage multiple shell sessions within a single terminal. Acting like an electronic MUX, it handles several inputs (shells) to one output (your terminal). Key features include: * Multiple sessions, each containing one or more windows * Independent windows running separate programs * Splitting windows into regions (panes) * A command prefix (default `Ctrl-a`) followed by command keys * Detachable sessions that continue running in the background * Socket connections, copy/scrollback mode, and extensive customization ![The image is a text description of terminal multiplexers, highlighting features like multiple inputs, session management, window splitting, ease of control, detachment, socket connections, and customization.](https://kodekloud.com/kk-media/image/upload/v1752881390/notes-assets/images/Linux-Professional-Institute-LPIC-1-Exam-101-GNU-Screen/terminal-multiplexers-features-description.jpg) ## Table of Contents * [History](#history) * [Getting Started](#getting-started) * [Prefix & Window Management](#prefix--window-management) * [Navigating & Closing Windows](#navigating--closing-windows) * [Splitting into Regions (Panes)](#splitting-into-regions-panes) * [Sessions: Listing, Naming & Killing](#sessions-listing-naming--killing) * [Detaching & Reattaching](#detaching--reattaching) * [Copy/Scrollback Mode](#copyscrollback-mode) * [Configuration](#configuration) * [Links & References](#links--references) *** ## History In the era of physical VT100 terminals (1970s/80s), users had no windowing system. GNU Screen, introduced in **1987**, emulated multiple VT100 sessions on a single terminal, transforming remote and local shell workflows. *** ## Getting Started To launch a new Screen session: ```bash theme={null} $ screen GNU Screen version 4.05.00 (GNU) 10-Dec-16 ... ``` Press **Space** or **Enter** to dismiss the welcome message. Behind the scenes, Screen has created **session 0** and **window 0**, presenting you with a familiar shell prompt. *** ## Prefix & Window Management All Screen commands begin with the **default prefix**: `Ctrl-a` (denoted `C-a`), followed by a command key. | Action | Key Combination | Alternative Command | | --------------------- | --------------- | ------------------- | | List windows | `C-a w` | — | | Create a new window | `C-a c` | — | | Rename current window | `C-a A` | — | | Create named window | — | `screen -t ` | ### Example: Managing Windows 1. In **window 0**, run: ```bash theme={null} $ ps PID TTY TIME CMD 974 pts/2 00:00:00 bash 981 pts/2 00:00:00 ps ``` 2. Press `C-a c` to create **window 1**, then run `ps` again. 3. Press `C-a w` to view the window list: ```bash theme={null} Num Name Flags 0 bash $ 1 bash *$ ``` 4. Rename window 1: * Press `C-a A` * Enter `ps` 5. Create **window 2** named “yetanotherwindow”: ```bash theme={null} $ screen -t yetanotherwindow ``` *** ## Navigating & Closing Windows **Switching Windows** | Action | Key Combination | | ----------------------- | --------------- | | Next window | `C-a n` | | Previous window | `C-a p` | | Jump to window number N | `C-a N` | | Choose from list | `C-a "` | After `C-a "`, use ↑/↓ and **Enter**: ```text theme={null} Num Name Flags 0 bash $ 1 ps $ 2 yetanotherwindow $ ``` **Closing Windows** * Exit the shell/program inside the window * Or press `C-a k`, then confirm with `y`: ```bash theme={null} Really kill this window [y/n] y Window 0 (bash) killed. ``` When the **last window** closes, the Screen session terminates automatically. *** ## Splitting into Regions (Panes) Divide your window into multiple regions for side-by-side workflows. | Action | Key Combination | | --------------------- | --------------- | | Split horizontally | `C-a S` | | Split vertically | `C-a \|` | | Move between regions | `C-a Tab` | | Close current region | `C-a X` | | Close all but current | `C-a Q` | > Empty regions display as two hyphens. Closing a region does **not** kill its window; it simply hides the view. *** ## Sessions: Listing, Naming & Killing ### Listing Active Sessions ```bash theme={null} $ screen -ls There is a screen on: 1037.pts-0.debian (Attached) 1 Socket in /run/screen/S-user. ``` * **1037**: Session PID * **pts-0.debian**: Terminal and host ### Naming a New Session ```bash theme={null} $ screen -S "my session" ``` Now `screen -ls` shows: ```bash theme={null} There are screens on: 1009.my session (Attached) 1037.pts-0.debian (Attached) 2 Sockets in /run/screen/S-user. ``` ### Killing a Session ```bash theme={null} $ screen -S 1037 -X quit ``` You can use the **session name** instead of the PID. *** ## Detaching & Reattaching | Action | Command | | ---------------------------------------------- | ------------------------ | | Detach (leave session running) | `C-a d` | | Reattach (single detached session) | `screen -r` | | Reattach by PID | `screen -r 1009` | | Reattach by name | `screen -r "my session"` | | Detach everywhere & reattach here | `screen -d -r` | | Create if missing, then attach (`strong`) | `screen -RR` | | Start a session in detached mode (for scripts) | `screen -d -m` | | Detach remote session & reattach here | `screen -D -r` | Use `man screen` for the complete list of attach/detach options: [https://man7.org/linux/man-pages/man1/screen.1.html](https://man7.org/linux/man-pages/man1/screen.1.html) *** ## Copy/Scrollback Mode Screen’s scrollback mode allows you to browse history and copy text across windows: 1. Enter mode: `C-a [` 2. Move cursor to the **start** of the text (arrow keys) 3. Press **Space** to begin selection 4. Move to the **end** of the text 5. Press **Space** to complete selection 6. Paste with: `C-a ]` ![The image shows instructions for using GNU Screen's scrollback mode, detailing key combinations for entering scrollback mode, moving to text, and marking the beginning and end of a selection.](https://kodekloud.com/kk-media/image/upload/v1752881390/notes-assets/images/Linux-Professional-Institute-LPIC-1-Exam-101-GNU-Screen/gnu-screen-scrollback-instructions-key-combinations.jpg) *** ## Configuration Screen reads two primary config files: | File | Scope | Typical Content | | --------------- | ------------- | ------------------------------ | | `/etc/screenrc` | System-wide | Global defaults and modules | | `~/.screenrc` | User-specific | Personal key bindings, layouts | Each config file may include: 1. **General settings** ```text theme={null} defscrollback 10000 ``` 2. **Key bindings** ```text theme={null} bind | split ____ ``` 3. **Terminal settings** ```text theme={null} defnonblock 5 ``` 4. **Startup screens** ```text theme={null} screen -t top top ``` Edit these files to tailor Screen’s behavior. Consult the [GNU Screen man page](https://man7.org/linux/man-pages/man1/screen.1.html) for a full directive reference. *** ## Links & References * [GNU Screen Home Page](https://www.gnu.org/software/screen/) * [Linux Journal: GNU Screen Tutorial](https://www.linuxjournal.com/article/3460) * [man screen (official)](https://man7.org/linux/man-pages/man1/screen.1.html)