using-tmux-for-interactive-commands

# Using tmux for Interactive Commands ## Overview Interactive CLI tools (vim, interactive git rebase, REPLs, etc.) cannot be controlled through standard bash because they require a real terminal. tmux provides detached sessions that can be controlled programmatically via `send-keys` and `capture-pane`. ## When to Use **Use tmux when:** - Running vim, nano, or other text editors programmatically - Controlling interactive REPLs (Python, Node, etc.) - Handling interactive git commands (`git rebase -i`, `git add -p`) - Working with full-screen terminal apps (htop, etc.) - Commands that require terminal control codes or readline **Don't use for:** - Simple non-interactive commands (use regular Bash tool) - Commands that accept input via stdin redirection - One-shot commands that don't need interaction ## Quick Reference | Task | Command | |------|---------| | Start session | `tmux new-session -d -s <name> <command>` | | Send input | `tmux send-keys -t <name> 'text' Enter` | | Capture output | `tmux capture-pane -t <name> -p` | | Stop session | `tmux kill-session -t <name>` | | List sessions | `tmux list-sessions` | ## Core Pattern ### Before (Won't Work) ```bash # This hangs because vim expects interactive terminal bash -c "vim file.txt" ``` ### After (Works) ```bash # Create detached tmux session tmux new-session -d -s edit_session vim file.txt # Send commands (Enter, Escape are tmux key names) tmux send-keys -t edit_session 'i' 'Hello World' Escape ':wq' Enter # Capture what's on screen tmux capture-pane -t edit_session -p # Clean up tmux kill-session -t edit_session ``` ## Implementation ### Basic Workflow 1. **Create detached session** with the interactive command 2. **Wait briefly** for initialization (100-500ms depending on command) 3. **Send input** using `send-keys` (can send special keys like Enter, Escape) 4. **Capture output** using `capture-pane -p` to see current screen state 5. **Repeat** steps 3-4 as needed 6. **Terminate** session when done ### Special Keys Common tmux key names: - `Enter` - Return/newline - `Escape` - ESC key - `C-c` - Ctrl+C - `C-x` - Ctrl+X - `Up`, `Down`, `Left`, `Right` - Arrow keys - `Space` - Space bar - `BSpace` - Backspace ### Working Directory Specify working directory when creating session: ```bash tmux new-session -d -s git_session -c /path/to/repo git rebase -i HEAD~3 ``` ### Helper Wrapper For easier use, see `/home/jesse/git/interactive-command/tmux-wrapper.sh`: ```bash # Start session /path/to/tmux-wrapper.sh start <session-name> <command> [args...] # Send input /path/to/tmux-wrapper.sh send <session-name> 'text' Enter # Capture current state /path/to/tmux-wrapper.sh capture <session-name> # Stop /path/to/tmux-wrapper.sh stop <session-name> ``` ## Common Patterns ### Python REPL ```bash tmux new-session -d -s python python3 -i tmux send-keys -t python 'import math' Enter tmux send-keys -t python 'print(math.pi)' Enter tmux capture-pane -t python -p # See output tmux kill-session -t python ``` ### Vim Editing ```bash tmux new-session -d -s vim vim /tmp/file.txt sleep 0.3 # Wait for vim to start tmux send-keys -t vim 'i' 'New content' Escape ':wq' Enter # File is now saved ``` ### Interactive Git Rebase ```bash tmux new-session -d -s rebase -c /repo/path git rebase -i HEAD~3 sleep 0.5 tmux capture-pane -t rebase -p # See rebase editor # Send commands to modify rebase instructions tmux send-keys -t rebase 'Down' 'Home' 'squash' Escape tmux send-keys -t rebase ':wq' Enter ``` ## Common Mistakes ### Not Waiting After Session Start **Problem:** Capturing immediately after `new-session` shows blank screen **Fix:** Add brief sleep (100-500ms) before first capture ```bash tmux new-session -d -s sess command sleep 0.3 # Let command initialize tmux capture-pane -t sess -p ``` ### Forgetting Enter Key **Problem:** Commands typed but not executed **Fix:** Explicitly send Enter ```bash tmux send-keys -t sess 'print("hello")' Enter # Note: Enter is separate argument ``` ### Using Wrong Key Names **Problem:** `tmux send-keys -t sess '\n'` doesn't work **Fix:** Use tmux key names: `Enter`, not `\n` ```bash tmux send-keys -t sess 'text' Enter # ✓ tmux send-keys -t sess 'text\n' # ✗ ``` ### Not Cleaning Up Sessions **Problem:** Orphaned tmux sessions accumulate **Fix:** Always kill sessions when done ```bash tmux kill-session -t session_name # Or check for existing: tmux has-session -t name 2>/dev/null ``` ## Real-World Impact - Enables programmatic control of vim/nano for file editing - Allows automation of interactive git workflows (rebase, add -p) - Makes REPL-based testing/debugging possible - Unblocks any tool that requires terminal interaction - No need to build custom PTY management - tmux handles it all