`screen` — Terminal Multiplexing Cheatsheet

A compact, practical reference for GNU Screen (the screen terminal multiplexer).

What is screen?

screen lets you run multiple terminal sessions inside one physical terminal. You can detach sessions and reattach later, share sessions between users, create named windows, split the display, use copy/scrollback mode, and log output.

Install

macOS (Homebrew):

brew install screen

Debian/Ubuntu:

sudo apt update && sudo apt install screen

Fedora/CentOS/RHEL:

sudo dnf install screen
# or on older CentOS: sudo yum install screen

Quick notes: modern Linux distros sometimes include screen by default. Alternative multiplexers include tmux and byobu.

Terminology / concepts

Prefix key: the default screen command prefix is Ctrl-a (written as C-a). You press C-a, then the command key. You can remap this in .screenrc.
Session: a running group of windows managed by screen. You can have multiple sessions.
Window: a shell (or program) inside a session. Each window has a numeric index and optional name.
Region: a split area of the display showing a window.

Quick reference (most-used commands)

Action	Command
Start a new session (unnamed)	`screen`
Start a named session	`screen -S work`
List sessions	`screen -ls`
Attach to a session	`screen -r work`
Force reattach (detach other first)	`screen -d -r work`
Multi-display attach (without detaching other)	`screen -x work`
Clean up dead sessions	`screen -wipe`
Reattach most recent session	`screen -RR`
Kill a session from outside	`screen -S work -X quit`
Send a command to a session (e.g., `ls` in window 0)	`screen -S work -p 0 -X stuff $'ls\n'`
Start a detached session running a command	`screen -dmS backup bash -c 'tar -czf /tmp/home.tar.gz ~'`

Key bindings inside screen

All key bindings use the prefix key C-a followed by the command key.

General

Key	Action
`C-a` `?`	Show all key bindings (help)
`C-a` `d`	Detach from current session
`C-a` `D D`	Power detach (detach and logout)
`C-a` `x`	Lock the screen session
`C-a` `:`	Enter command mode

Windows

Key	Action
`C-a` `c`	Create a new window
`C-a` `A`	Rename current window (type name, then Enter)
`C-a` `k`	Kill current window (confirm with `y`)
`C-a` `n`	Switch to next window
`C-a` `p`	Switch to previous window
`C-a` `<number>`	Switch to window by number (e.g., `C-a` `2`)
`C-a` `"`	List windows (interactive selector)
`C-a` `w`	Show window list in status line
`C-a` `'`	Select window by name or number prompt
`C-a` `:number <n>`	Move current window to index `<n>`

Splitting the display (regions)

Key	Action
`C-a` `S`	Split horizontally
`C-a` `\\|`	Split vertically (screen 4.x+)
`C-a` `TAB`	Switch focus to next region
`C-a` `X`	Remove current region
`C-a` `Q`	Remove all regions except the current one
`C-a` `:resize <n>`	Resize current region to `<n>` lines
`C-a` `:fit`	Fit region to current terminal size
`C-a` `c`	Open a window in the current region

Copy/scrollback mode

Key	Action
`C-a` `[`	Enter copy/scrollback mode
Arrow keys / `h j k l`	Navigate (vi-style, depending on config)
`PageUp` / `PageDown`	Scroll pages
`Space`	Start/end selection
`C-a` `]`	Paste copied text into current window

Tip: Increase scrollback buffer in .screenrc with defscrollback 5000.

Logging

Key / Command	Action
`C-a` `H`	Toggle logging for the current window
`screen -S work -X log on`	Enable logging from outside
`screen -S work -X logfile /path/to/log.txt`	Set log file path from outside
`screen -S work -X log off`	Disable logging from outside

Log files are named screenlog.0, screenlog.1, etc. by default.

Disconnect vs terminate

Action	How
Detach (leave processes running)	`C-a` `d`
Power detach (detach + logout)	`C-a` `D D`
Quit session from inside	`C-a` `:quit`
Quit session from outside	`screen -S work -X quit`

Environment variables

Variable	Description
`$STY`	Name of the current screen session (empty if not inside screen)
`$WINDOW`	Number of the current window (useful for scripting and prompts)

Example workflows

Start a persistent session and run a long command:

screen -S longjob
# inside screen run: python long_script.py
# Detach: C-a d
# Reattach to check progress:
screen -r longjob

Share a session with another user (multiuser mode):

# as owner inside screen
C-a :multiuser on
C-a :acladd friendusername

Then the other user can attach to the session by name if permissions allow.

Run a background command in a screen and detach immediately:

screen -dmS backup bash -c 'tar -czf /tmp/home.tar.gz /home/you'
# -d -m: start detached, -S name

Send a literal Ctrl-C to a running window:

screen -S work -p 0 -X stuff $'\003'

Run a command in a new named window:

screen -S myproj -X screen -t build bash -c 'make build; exec bash'

Sample .screenrc

Drop this in ~/.screenrc (small, sensible defaults):

# Use C-a as prefix (default). To change: escape ^Aa
# Increase scrollback buffer
defscrollback 5000

# Set a better hardstatus (shows session/window info) if your build supports it
hardstatus alwayslastline
hardstatus string "%{= kG}[ %H ] %=%{= kw}%{= kG}%S %=%{= kG}%Y-%m-%d %c"

# Start windows with names
screen -t editor 0 $SHELL
screen -t server 1 $SHELL

# Bind a key to quickly create a new named window
bind c screen -t "shell-#" 0 $SHELL

# Logging filename template
logfile $HOME/screenlogs/screenlog.%n

# Allow multiuser (turn on manually inside a session for safety):
# multiuser on

# Status line colors can be customized further

# Example: automatically create 3 windows at startup
# screen -t shell1 0
# screen -t shell2 1
# screen -t shell3 2

Create directory for logs (if you use the logfile above):

mkdir -p ~/screenlogs

Troubleshooting

Problem	Solution
Can’t reattach	Run `screen -ls` to check session state. If `Attached`, use `screen -d -r <id>` to steal it.
Dead sessions lingering	Run `screen -wipe` to clean them up.
Permission denied when sharing	Ensure correct pts permissions or use `multiuser` + `acladd` inside screen.
Copy mode navigation unresponsive	Try `export TERM=xterm-256color` or check `termcap` entries.
Session name collisions	Always use unique names with `-S` to avoid attaching to the wrong session.

TL;DR

Action	Command
Start named session	`screen -S name`
List sessions	`screen -ls`
Attach	`screen -r name`
Detach (inside)	`C-a` `d`
New window	`C-a` `c`
List windows	`C-a` `"`
Show help	`C-a` `?`
Copy mode	`C-a` `[`
Toggle logging	`C-a` `H`
Kill session	`screen -S name -X quit`
Clean up dead sessions	`screen -wipe`

screen — Terminal Multiplexing Cheatsheet