Mastering the Linux Screen Command

Introduction

The screen command in Linux offers the ability to launch and manage multiple shell sessions from a single SSH session. This allows processes to be detached from a session and reattached later, ensuring continuous operation even if the connection drops.

Syntax

screen [-opts] [cmd [args]]

Options

• -a: Forces all capabilities into each window's termcap.
• -A -[r|R]: Adapts all windows to the new display dimensions.
• -c file: Reads configuration from a specified file instead of .screenrc.
• -d (-r): Detaches an elsewhere running screen (and reattaches here).
• -dmS name: Starts as a daemon - Screen session in detached mode.
• -D (-r): Detaches and logs out remote (and reattaches here).
• -D -RR: Does whatever is needed to get a screen session.
• -e xy: Changes the command characters.
• -f: Turns flow control on, -fn for off, -fa for auto.
• -h lines: Sets the size of the scrollback history buffer.
• -i: Interrupts output sooner when flow control is on.
• -l: Enables login mode (updates /var/run/utmp).
• -ls [match]: Displays all the attached screens.
• -L: Turns on output logging.
• -m: Ignores $STY variable, creates a new screen session.
• -O: Chooses optimal output over exact vt100 emulation.
• -p window: Preselects the named window if it exists.
• -q: Quiet startup. Exits with a non-zero return code if unsuccessful.
• -Q: Sends response to the stdout of the querying process.
• -r [session]: Reattaches to a detached screen process.
• -R: Reattaches if possible, otherwise starts a new session.
• -S sockname: Names the session .sockname.
• -t title: Sets window's name.
• -T term: Uses term as $TERM for windows instead of "screen".
• -U: Enables UTF-8 encoding.
• -v: Prints "Screen version 4.06.02 (GNU) 23-Oct-17".
• -x: Attaches to a not detached screen (Multi display mode).
• -X: Executes a screen command in the specified session.

Shortcut Keys

• Ctrl-a + c: Creates a new window.
• Ctrl-a + w: Displays all open windows.
• Ctrl-a + A: Renames the current window.
• Ctrl-a + n: Goes to the next window.
• Ctrl-a + p: Goes to the previous window.
• Ctrl-a + Ctrl-a: Switches back to the last window used.
• Ctrl-a + k: Closes (kills) the current window.
• Ctrl-a + S: Splits the window horizontally. Use Ctrl-a + Tab to switch.
• Ctrl-a + |: Splits the window vertically.
• Ctrl-a + d: Detaches the session.
• Ctrl-a + r: Reattaches to a session.
• Ctrl-a + [: Starts copy mode.
• Ctrl-a + ]: Pastes copied text.

Examples

Installing Screen

To install the screen command:

sudo apt install screen

Starting a New Session

Start a new window within screen:

screen

Naming a Session

Start a named session:

screen -S mysession

Listing Sessions

List all attached and detached sessions:

screen -ls

Detaching a Session

Detach a session:

screen -d 1643

Reattaching a Session

Reattach a session:

screen -r 1643

Additional Resources

• Manual Page: View detailed manual via:

man screen

• Help Page: Check basic help information:

screen --help

The screen command is a powerful tool that enhances productivity by allowing users to keep processes running in the background and manage them efficiently.