tmux

Terminal multiplexer for background processes, output capture, and session management. Every process runs in a named session you can inspect later.

Running Background Processes

Start a command in a named detached session:

tmux new-session -d -s myserver 'python -m http.server 8080'
tmux new-session -d -s build -c /path/to/project 'make build'

Keep a session alive after the command completes:

tmux new-session -d -s task 'command; exec bash'

Only create if it doesn't exist:

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

Capturing Output

Get the output from a running session:

tmux capture-pane -t mysession -p           # Visible output only
tmux capture-pane -t mysession -p -S -      # Full scrollback history
tmux capture-pane -t mysession -p -S -100   # Last 100 lines
tmux capture-pane -t mysession -p > file.txt  # Save to file

Sending Input

Send keystrokes to a session:

tmux send-keys -t mysession 'echo hello' Enter    # Type and press Enter
tmux send-keys -t mysession C-c                    # Send Ctrl+C

Waiting for Completion

Signal when a job finishes, then wait for it:

tmux new-session -d -s job 'command; tmux wait-for -S job-done'
tmux wait-for job-done

Session Management

tmux ls                                    # List all sessions
tmux kill-session -t myserver              # Kill specific session
tmux kill-server                           # Kill all sessions

Common Patterns

Development servers:

tmux new-session -d -s backend 'bun run backend'
tmux new-session -d -s frontend 'bun run frontend'

Run and capture output in a script:

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

Tips

• Use -c /path to set working directory when creating a session
• Use exec bash to keep sessions alive after commands finish
• Use -S - with capture-pane to get full scrollback history