The screen Command — Persistent Terminal Sessions

Overview

screen is a terminal multiplexer that lets you create persistent shell sessions. If your SSH connection drops — due to a timeout, network issue, or closing your laptop — any process running inside a screen session keeps running. You can reconnect later and pick up right where you left off.

This is essential for long-running tasks like database imports, large file transfers, software compilations, or any operation that shouldn’t be interrupted.

Starting a Session

Create a new session

screen

Create a named session (recommended)

screen -S backup

Naming sessions makes it easy to identify and reattach to the right one.

Detaching from a Session

While inside a screen session, press:

Ctrl + A, then D

This detaches you from the session — it continues running in the background. You’ll see a message like:

[detached from 12345.backup]

Your SSH session is now free, and the screen session is still active.

Reattaching to a Session

Reattach to the most recent session

screen -r

Reattach to a named session

screen -r backup

Reattach to a specific session by ID

screen -r 12345

Force reattach (if the session is still marked as attached)

screen -d -r backup

This detaches any other connection to the session first, then reattaches you.

Listing All Sessions

screen -ls

Sample output:

There are screens on:
    12345.backup    (Detached)
    12346.migration (Attached)
2 Sockets in /var/run/screen/S-username.

Ending a Session

From inside the screen session, simply type:

exit

Or press Ctrl + D. The session is terminated when the last shell inside it exits.

Essential Keyboard Shortcuts

All screen shortcuts start with Ctrl + A (the command prefix), followed by a key:

Practical Hosting Examples

Run a database import that takes hours

screen -S db-import
mysql -u username -p database_name < large-database.sql
# Detach with Ctrl+A, D — the import continues in the background

Run a long file transfer

screen -S transfer
rsync -avzP /source/ user@remote:/destination/
# Detach safely

Run a script that processes data overnight

screen -S processing
python3 process_data.py
# Detach and come back in the morning

Tips

• Always use screen (or tmux) for any task that takes more than a few minutes. SSH disconnections are common and can interrupt critical operations.
• Give your sessions meaningful names with -S so you can easily identify them later.
• If screen is not installed, ask your hosting provider or install it with sudo apt install screen (Debian/Ubuntu) or sudo yum install screen (CentOS/RHEL).
• tmux is a modern alternative to screen with similar functionality and additional features.