Bildschirm Cheatsheet

Überblick

GNU Screen ist ein Terminal Multiplexer, mit dem Sie mehrere Terminalsitzungen innerhalb eines einzigen Terminalfensters ausführen können. Es ermöglicht Sitzungsbeharrlichkeit, Ablösung und Wiederanbringung, so dass es ideal für Remote-Arbeit und Langlauf-Prozesse.

Installation

Paketmanager

# Ubuntu/Debian
sudo apt install screen

# macOS
brew install screen

# CentOS/RHEL
sudo yum install screen

# Arch Linux
sudo pacman -S screen

# From source
wget https://ftp.gnu.org/gnu/screen/screen-4.9.0.tar.gz
tar -xzf screen-4.9.0.tar.gz
cd screen-4.9.0 && ./configure && make && sudo make install
```_

## Basisnutzung

### Startbildschirm
```bash
# Start new screen session
screen

# Start named session
screen -S sessionname

# Start session with command
screen -S mysession htop

# Start detached session
screen -d -m -S mysession

# Start session with specific shell
screen -S mysession bash
```_

### Sitzungsmanagement
```bash
# List sessions
screen -ls
screen -list

# Attach to session
screen -r sessionname
screen -r 12345  # Using session ID

# Attach to session (force if attached elsewhere)
screen -d -r sessionname

# Detach from session
# Inside screen: Ctrl+a d

# Kill session
screen -S sessionname -X quit

# Kill all sessions
pkill screen
```_

## Schlüsselbindungen (Standard-Präfix: Ctrl+a)

### Sitzungsbefehle

Ctrl+a d # Detach from session Ctrl+a D D # Detach and logout Ctrl+a # Kill all windows and terminate Ctrl+a : # Enter command mode

### Fensterbefehle

Ctrl+a c # Create new window Ctrl+a n # Next window Ctrl+a p # Previous window Ctrl+a 0-9 # Switch to window by number Ctrl+a " # List windows Ctrl+a w # Show window list Ctrl+a k # Kill current window Ctrl+a A # Rename current window Ctrl+a ' # Prompt for window number to switch to

### Window Navigation

Ctrl+a Ctrl+a # Switch to last window Ctrl+a l # Refresh screen Ctrl+a L # Toggle login state Ctrl+a M # Monitor window for activity Ctrl+a _ # Monitor window for silence

### Split Screen (Regionen)

Ctrl+a S # Split horizontally Ctrl+a|# Split vertically (if supported) Ctrl+a Tab # Switch between regions Ctrl+a Q # Close all regions except current Ctrl+a X # Close current region

### Kopiermodus

Ctrl+a [ # Enter copy mode Ctrl+a ] # Paste buffer Ctrl+a > # Write buffer to file Ctrl+a < # Read buffer from file

## Kopiermodus Navigation

### Geben Sie den Kopiermodus

Ctrl+a [ # Enter copy mode Ctrl+a Esc # Enter copy mode (alternative)

### Bewegung im Kopiermodus

h, j, k, l # Move cursor (vi-style) Arrow keys # Move cursor w # Next word b # Previous word 0 # Beginning of line $ # End of line g # Go to beginning of buffer G # Go to end of buffer Ctrl+f # Page down Ctrl+b # Page up / # Search forward ? # Search backward n # Next search result N # Previous search result

### Auswahl und Kopieren

Space # Start/end selection Enter # Copy selection and exit copy mode Esc # Exit copy mode

## Konfiguration

### Konfigurationsdatei (~/.screenrc)
```bash
# Basic settings
startup_message off
defscrollback 10000
hardstatus alwayslastline
hardstatus string '%\\\\{= kG\\\\}[ %\\\\{G\\\\}%H %\\\\{g\\\\}][%= %\\\\{=kw\\\\}%?%-Lw%?%\\\\{r\\\\}(%\\\\{W\\\\}%n*%f%t%?(%u)%?%\\\\{r\\\\})%\\\\{w\\\\}%?%+Lw%?%?%= %\\\\{g\\\\}][%\\\\{B\\\\}%Y-%m-%d %\\\\{W\\\\}%c %\\\\{g\\\\}]'

# Set default shell
shell -$SHELL

# Enable 256 colors
term screen-256color

# Mouse support (if available)
mousetrack on

# Automatically detach on hangup
autodetach on

# Change escape key
escape ^Aa  # Default is Ctrl+a

# Window numbering
bind c screen 1
bind ^c screen 1
bind 0 select 10
screen 1

# Split screen bindings
bind|split -v
bind - split
bind + resize +5
bind = resize =
bind _ resize -5

# Window navigation
bind j focus down
bind k focus up
bind h focus left
bind l focus right

# Reload config
bind r source ~/.screenrc

# Logging
bind L log

# Monitor activity
bind m monitor
bind M monitor
```_

### Erweiterte Konfiguration
```bash
# Status line customization
hardstatus on
hardstatus alwayslastline
hardstatus string "%\\\\{.bW\\\\}%-w%\\\\{.rW\\\\}%n %t%\\\\{-\\\\}%+w %=%\\\\{..G\\\\} %H %\\\\{..Y\\\\} %m/%d %C%a "

# Window titles
shelltitle "$|bash"

# Startup windows
screen -t "editor" 1 vim
screen -t "server" 2
screen -t "logs" 3 tail -f /var/log/messages

# Key bindings for common tasks
bind ^k kill
bind k kill
bind ^\ quit
bind \\ quit
bind ^h hardcopy
bind h hardcopy

# Scrollback buffer
defscrollback 10000

# Visual bell
vbell on
vbell_msg "   Wuff  ----  Wuff!!  "

# Activity monitoring
activity "Activity in %t(%n)"

# Silence monitoring
silence on
silencewait 15

# Automatic window naming
shelltitle '$|bash'

# Password protection
password ODSJQf.4IJN7E    # Encrypted password

# Multiuser mode
multiuser on
acladd user1,user2
```_

## Erweiterte Funktionen

### Mehrere Benutzer
```bash
# Enable multiuser mode
screen -S shared
# In screen: Ctrl+a :multiuser on
# In screen: Ctrl+a :acladd username

# Other user connects
screen -x username/shared
```_

### Sitzungsaustausch
```bash
# Start shared session
screen -S shared

# Allow others to attach
# In screen: Ctrl+a :multiuser on
# In screen: Ctrl+a :acladd otheruser

# Other user attaches
screen -x shared
```_

### Protokoll
```bash
# Enable logging for window
# In screen: Ctrl+a H

# Log to specific file
# In .screenrc:
logfile /tmp/screen-%t.log

# Automatic logging
deflog on
```_

### Überwachung
```bash
# Monitor window for activity
Ctrl+a M

# Monitor for silence
Ctrl+a _

# Set silence timeout (seconds)
# In .screenrc:
silencewait 30
```_

## Kommandozeilenoptionen

### Sitzungsmanagement
```bash
# Create detached session
screen -d -m -S mysession

# Create session and run command
screen -d -m -S mysession bash -c 'cd /var/log && tail -f messages'

# Send command to session
screen -S mysession -X stuff 'ls -la\n'

# Send command to specific window
screen -S mysession -p 0 -X stuff 'htop\n'

# Capture window content
screen -S mysession -p 0 -X hardcopy /tmp/screen.dump
```_

### Window Management
```bash
# Create window with title
screen -S mysession -X screen -t "editor" vim

# Kill specific window
screen -S mysession -p 1 -X kill

# List windows
screen -S mysession -Q windows
```_

## Schrift

### Automatisierungsskripte
```bash
#!/bin/bash
# dev-setup.sh

SESSION="development"

# Check if session exists
if ! screen -list|grep -q "$SESSION"; then
    # Create new session
    screen -d -m -S "$SESSION"

    # Setup windows
    screen -S "$SESSION" -X screen -t "editor" 1 vim
    screen -S "$SESSION" -X screen -t "server" 2
    screen -S "$SESSION" -X screen -t "logs" 3 tail -f /var/log/messages

    # Send commands to windows
    screen -S "$SESSION" -p 2 -X stuff 'cd ~/project && npm start\n'

    # Select first window
    screen -S "$SESSION" -X select 1
fi

# Attach to session
screen -r "$SESSION"
```_

### Batch Operationen
```bash
# Kill all sessions
|  | screen -ls | grep Detached | cut -d. -f1 | awk '\\\\{print $1\\\\}' | xargs kill |  |

# Send command to all windows
for i in \\\\{0..9\\\\}; do
    screen -S mysession -p $i -X stuff 'echo "Hello from window $i"\n'
done

# Create multiple sessions
for name in web api db; do
    screen -d -m -S "$name"
done
```_

## Integration

### Mit SSH
```bash
# Auto-start screen on SSH login
# Add to ~/.bashrc on remote server
if [ -z "$STY" ] && [ -n "$SSH_CONNECTION" ]; then
    screen -RR ssh_session
fi

# Or use a function
ssh_screen() \\\\{
    ssh -t "$1" 'screen -RR'
\\\\}
```_

### Mit System Services
```bash
# Run service in screen
screen -d -m -S myservice /path/to/service

# Systemd service file
[Unit]
Description=My Service in Screen
After=network.target

[Service]
Type=forking
User=myuser
ExecStart=/usr/bin/screen -d -m -S myservice /path/to/service
ExecStop=/usr/bin/screen -S myservice -X quit

[Install]
WantedBy=multi-user.target
```_

## Vergleich mit tmux

### Bildschirm vs tmux

Screen: + Older, more stable + Simpler configuration + Better for basic use cases + Lower resource usage - Less active development - Fewer features - Limited pane support

tmux: + More active development + Better pane management + More features + Better scripting support - Steeper learning curve - More complex configuration ```_

Tipps und Tricks

Produktivität Tipps

```bash

Quick session switching

alias s='screen -ls' alias sr='screen -r' alias sn='screen -S'

Function to create or attach

sc() \\{ if [ \(# -eq 0 ]; then screen -ls else | | screen -r "\)1" | | screen -S "$1" | | fi \\}

Nested screen sessions

Change escape key for inner session

In .screenrc: escape ^Bb

```_

Nützliche Alias

```bash

Add to ~/.bashrc

alias sl='screen -ls' alias sr='screen -r' alias ss='screen -S' alias sk='screen -X -S'

Function for easy session management

screen_session() \\{ case "\(1" in ls|list) screen -ls ;; new) screen -S "\)2" ;; attach) screen -r "\(2" ;; kill) screen -S "\)2" -X quit ;; *) | | echo "Usage: screen_session \\{ls | new | attach | kill\\} [session_name]" | | ;; esac \\} ```_

Fehlerbehebung

Gemeinsame Themen

```bash

Fix "Cannot open your terminal '/dev/pts/0'" error

script /dev/null

Or use:

screen -x

Dead session cleanup

screen -wipe

Permission issues

chmod 755 /var/run/screen

Check screen version

screen -v

Debug mode

screen -d -m -L -S debug command ```_

Erholung

```bash

Recover dead sessions

screen -D -R

Force detach and reattach

screen -d sessionname screen -r sessionname

Clean up dead sessions

screen -wipe ```_

Sicherheit

Zugriffskontrolle

```bash

Set password protection

In .screenrc:

password your_encrypted_password

Generate encrypted password

screen -X password

Multiuser access control

multiuser on acladd username aclchg username +rwx "#" ```_

Best Practices

```bash

Use named sessions

screen -S descriptive_name

Regular cleanup

screen -wipe

Monitor session activity

In .screenrc:

activity "Activity in %t(%n)"

Limit scrollback buffer

defscrollback 1000 ```_

Ressourcen

• offizielle Dokumentation: [gnu.org/software/screen](LINK_1_
• Manual*: man screen_
• Info*: info screen_
• Beispiele: /usr/share/doc/screen/examples/_