Tmux Control

Tmux Control

Remote-control tmux sessions programmatically. tmux is usually pre-installed; if not, install it with your package manager.

Prerequisites

# macOS
brew install tmux

# Ubuntu/Debian
sudo apt install tmux

# Check version
tmux -V

Commands

Session Management

Sending Commands & Keystrokes

# Run a command in a session (sends text + Enter)
tmux send-keys -t <session> "ls -la" Enter

# Send to specific window and pane (session:window.pane)
tmux send-keys -t myapp:0.1 "npm run dev" Enter

# Send a raw keystroke (e.g. Ctrl+C)
tmux send-keys -t <session> C-c

# Send without pressing Enter (useful for partial input)
tmux send-keys -t <session> "some text"

Capturing Pane Output

# Capture current visible pane content
tmux capture-pane -t <session> -p

# Capture full scrollback buffer to file
tmux capture-pane -t <session> -p -S - > workspace/tmux-output.txt

# Capture last 100 lines
tmux capture-pane -t <session> -p -S -100

Window & Pane Management

# Create a new window in a session
tmux new-window -t <session> -n <window-name>

# Split pane horizontally (left/right)
tmux split-window -h -t <session>

# Split pane vertically (top/bottom)
tmux split-window -v -t <session>

# List windows in a session
tmux list-windows -t <session>

# List panes in a session
tmux list-panes -t <session>

Usage Examples

Create a session and run a dev server:

tmux new-session -d -s devserver
tmux send-keys -t devserver "cd ~/project && pnpm dev" Enter

Capture output from a running process:

tmux capture-pane -t devserver -p -S -50

Send Ctrl+C then restart:

tmux send-keys -t devserver C-c
sleep 1
tmux send-keys -t devserver "pnpm dev" Enter

Run a command and capture result:

tmux new-session -d -s scratch
tmux send-keys -t scratch "git status" Enter
sleep 1
tmux capture-pane -t scratch -p
tmux kill-session -t scratch

Rules

• Always check if tmux is installed first: which tmux
• If not installed, show the install command and stop
• Before sending keys, verify the session exists with tmux has-session -t <name>
• When capturing output, always save to workspace/tmux-<session>-<timestamp>.txt for long output
• Add appropriate sleep between send-keys and capture-pane to allow commands to complete
• Never send destructive commands (rm -rf, DROP TABLE, etc.) without explicit user confirmation
• Use -d (detached) when creating sessions programmatically — never attach interactively
• Confirm actions with a single line: "Sent '' to session "