tmux

name	tmux
description	Manage background jobs, capture command output, and handle session multiplexing. Use when running long commands, capturing output from detached processes, or managing concurrent tasks in headless environments.

tmux

Terminal multiplexer for background jobs, output capture, and session control.

Quick Reference

Command	Description
tmux new -d -s name 'cmd'	Run command in background session
tmux capture-pane -t name -p	Capture session output
tmux send-keys -t name 'text' Enter	Send input to session
tmux kill-session -t name	Kill session
tmux ls	List sessions
tmux has -t name	Check if session exists

Running Background Processes

# Run command in new detached session
tmux new-session -d -s myserver 'python -m http.server 8080'

# With specific working directory
tmux new-session -d -s build -c /path/to/project 'make build'

# Keep session alive after command ends
tmux new-session -d -s task 'command; exec bash'

# Run only if session does not already exist
tmux has -t myserver || tmux new-session -d -s myserver 'command'

Capturing Output

# Capture visible output
tmux capture-pane -t mysession -p

# Capture whole scrollback
tmux capture-pane -t mysession -p -S -

# Capture last N lines
tmux capture-pane -t mysession -p -S -100

# Save to file
tmux capture-pane -t mysession -p > output.txt

# Capture with escape sequences (colors)
tmux capture-pane -t mysession -p -e

Sending Input

# Send text and press Enter
tmux send-keys -t mysession 'echo hello' Enter

# Send without Enter
tmux send-keys -t mysession 'some-text'

# Send Ctrl+C
tmux send-keys -t mysession C-c

Session Management

# List sessions
tmux list-sessions
tmux ls

# Kill specific session
tmux kill-session -t myserver

# Kill all sessions
tmux kill-server

# Check whether session exists
tmux has -t mysession

Wait for Completion

# Signal completion from command
tmux new-session -d -s job 'command; tmux wait-for -S job-done'

# Wait for signal
tmux wait-for job-done

Common Patterns

Development Servers

tmux new-session -d -s backend 'bun run backend'
tmux new-session -d -s frontend 'bun run frontend'
tmux new-session -d -s tests 'vitest --watch'

Run and capture output

tmux new-session -d -s job 'command'
sleep 0.5
output=$(tmux capture-pane -t job -p)
echo "$output"

Conditional session

tmux has -t myserver || tmux new-session -d -s myserver 'command'

Clean up

tmux kill-session -t backend
tmux kill-session -t frontend
tmux kill-server  # Kill all

Tips

• Use tmux new-session -d for background jobs
• Use tmux capture-pane -p -S - for whole scrollback
• Use tmux has -t name to check whether session exists
• Use tmux kill-server to clean up all sessions
• Use -c /path to set working directory
• Use exec bash to keep session alive after command