Tmux

Remote-control tmux sessions for interactive CLIs by sending keystrokes and scraping pane output.

tmux Session Control

Control tmux sessions by sending keystrokes and reading output. Essential for managing Claude Code sessions.

When to Use

✅ USE this skill when:

• Monitoring Claude/Codex sessions in tmux
• Sending input to interactive terminal applications
• Scraping output from long-running processes in tmux
• Navigating tmux panes/windows programmatically
• Checking on background work in existing sessions

When NOT to Use

❌ DON'T use this skill when:

• Running one-off shell commands → use exec tool directly
• Starting new background processes → use exec with background:true
• Non-interactive scripts → use exec tool
• The process isn't in tmux
• You need to create a new tmux session → use exec with tmux new-session

Example Sessions

Session	Purpose
shared	Primary interactive session
worker-2 - worker-8	Parallel worker sessions

Common Commands

List Sessions

bash

tmux list-sessions
tmux ls

Capture Output

bash

# Last 20 lines of pane
tmux capture-pane -t shared -p | tail -20

# Entire scrollback
tmux capture-pane -t shared -p -S -

# Specific pane in window
tmux capture-pane -t shared:0.0 -p

Send Keys

bash

# Send text (doesn't press Enter)
tmux send-keys -t shared "hello"

# Send text + Enter
tmux send-keys -t shared "y" Enter

# Send special keys
tmux send-keys -t shared Enter
tmux send-keys -t shared Escape
tmux send-keys -t shared C-c          # Ctrl+C
tmux send-keys -t shared C-d          # Ctrl+D (EOF)
tmux send-keys -t shared C-z          # Ctrl+Z (suspend)

Window/Pane Navigation

bash

# Select window
tmux select-window -t shared:0

# Select pane
tmux select-pane -t shared:0.1

# List windows
tmux list-windows -t shared

Session Management

bash

# Create new session
tmux new-session -d -s newsession

# Kill session
tmux kill-session -t sessionname

# Rename session
tmux rename-session -t old new

Sending Input Safely

For interactive TUIs (Claude Code, Codex, etc.), split text and Enter into separate sends to avoid paste/multiline edge cases:

bash

tmux send-keys -t shared -l -- "Please apply the patch in src/foo.ts"
sleep 0.1
tmux send-keys -t shared Enter

Claude Code Session Patterns

Check if Session Needs Input

bash

# Look for prompts
tmux capture-pane -t worker-3 -p | tail -10 | grep -E "❯|Yes.*No|proceed|permission"

Approve Claude Code Prompt

bash

# Send 'y' and Enter
tmux send-keys -t worker-3 'y' Enter

# Or select numbered option
tmux send-keys -t worker-3 '2' Enter

Check All Sessions Status

bash

for s in shared worker-2 worker-3 worker-4 worker-5 worker-6 worker-7 worker-8; do
  echo "=== $s ==="
  tmux capture-pane -t $s -p 2>/dev/null | tail -5
done

Send Task to Session

bash

tmux send-keys -t worker-4 "Fix the bug in auth.js" Enter

Notes

• Use capture-pane -p to print to stdout (essential for scripting)
• -S - captures entire scrollback history
• Target format: session:window.pane (e.g., shared:0.0)
• Sessions persist across SSH disconnects