Quick Reference Card
| Action | Command | Notes |
|---|---|---|
| Start session | screen |
Basic session |
| Start named session | screen -S name |
Recommended! |
| Detach session | Ctrl + A, then D |
Keep running! |
| List sessions | screen -ls |
Show all active |
| Reattach session | screen -r name |
Resume work |
| Kill session | exit or screen -S name -X quit |
End session |
| Split horizontally | Ctrl + A, then S |
Advanced |
| Switch between splits | Ctrl + A, then Tab |
Advanced |
What is Linux Screen?
When working on Linux servers, network disconnections can kill your running processes. The screen command creates persistent terminal sessions that survive disconnections, letting you pick up exactly where you left off.
Perfect for:
- Long-running backups or file transfers
- Compiling large codebases
- System monitoring tasks
- Any process that takes hours to complete
Installation
Most Linux distributions include screen by default. If missing:
Ubuntu/Debian:
sudo apt update && sudo apt install screen
CentOS/RHEL/Rocky:
sudo yum install screen
# or on newer versions:
sudo dnf install screen
Arch Linux:
sudo pacman -S screen
Verify installation:
screen --version
Essential Screen Commands
1. Starting Sessions
Basic session:
screen
Named session (recommended):
screen -S backup-job
screen -S database-migration
screen -S monitoring
💡 Pro tip: Always name your sessions for easy identification!
2. The Magic Detach Command
Detach and keep running:
Ctrl + A, then D
This is the most important screen command. Your process continues running in the background.
3. Managing Sessions
List all active sessions:
screen -ls
Sample output:
There are screens on:
15234.backup-job (Detached)
15891.monitoring (Attached)
16124.database-migration (Detached)
Reattach to a session:
screen -r backup-job
screen -r 15234 # Using session ID also works
Force reattach (if session shows as Attached):
screen -r -d backup-job
4. Ending Sessions
Clean exit (from within the screen):
exit
Force kill a session:
screen -S backup-job -X quit
Kill all detached sessions:
screen -wipe
Real-World Examples
Example 1: Database Backup
# Start named session
screen -S db-backup
# Run your backup command
mysqldump -u root -p mydb > backup.sql
# Detach with Ctrl+A, D
# Check progress later with: screen -r db-backup
Example 2: File Synchronization
# Start session for long rsync job
screen -S sync-files
# Start the sync
rsync -avz --progress /local/data/ user@server:/remote/backup/
# Detach and come back later
# Reattach: screen -r sync-files
Example 3: System Monitoring
# Create monitoring session
screen -S monitoring
# Run continuous monitoring
htop
# or
tail -f /var/log/syslog
# Detach and let it run
Advanced Tips
Multiple Windows in One Session
# Create new window: Ctrl + A, then C
# Switch windows: Ctrl + A, then N (next) or P (previous)
# List windows: Ctrl + A, then W
Split Screen View
# Horizontal split: Ctrl + A, then S
# Vertical split: Ctrl + A, then |
# Switch splits: Ctrl + A, then Tab
# Close split: Ctrl + A, then X
Session Logging
# Start session with logging
screen -L -S logged-session
# Log file saved as: screenlog.0
Troubleshooting
Problem: Can't reattach - session shows as "Attached"
Solution:
screen -r -d session-name # Force detach and reattach
Problem: Lost session names
Solution:
screen -ls # Lists all sessions with IDs
screen -r [session-id] # Reattach using ID number
Problem: Too many dead sessions
Solution:
screen -wipe # Cleans up dead sessions
Screen vs Alternatives
| Tool | Best For | Pros | Cons |
|---|---|---|---|
| screen | Simple persistent sessions | Lightweight, universal | Basic features |
| tmux | Advanced terminal multiplexing | More features, better splits | Steeper learning curve |
| nohup | One-off background jobs | Simple for single commands | No interaction |
Why Screen Matters for System Administrators
In production environments, screen is essential because:
- Reliability: Critical processes don't die with your SSH session
- Monitoring: You can check long-running jobs anytime
- Collaboration: Multiple users can attach to the same session
- Debugging: Easily access logs and outputs from persistent sessions
Quick Start Workflow
- SSH to your server
- Start named screen:
screen -S my-task - Run your command
- Detach:
Ctrl + A, D - Disconnect from server (process keeps running!)
- Later: SSH back and reattach:
screen -r my-task
That's it! You've mastered the essential skill that separates casual Linux users from professionals.
Conclusion
Master these screen basics and you'll never lose work to dropped connections again. The screen command is a fundamental tool for anyone working with Linux servers, remote development, or long-running processes.
Remember the golden rule: Always detach (Ctrl + A, D) instead of closing your terminal!