Tmux

---
name: tmux
description: Remote control tmux sessions for interactive CLIs (python, gdb, etc.) by sending keystrokes and scraping pane output. TRIGGER when user requests to "operate tmux", "split pane", "run in tmux", "interactive debug", "start REPL", or running interactive CLI commands.
license: Vibecoded
---

# tmux Skill

Use tmux as a programmable terminal multiplexer for interactive work. Works on Linux and macOS with stock tmux; avoid custom config by using a private socket.

## Quickstart (isolated socket)

```bash
SOCKET_DIR=${TMPDIR:-/tmp}/claude-tmux-sockets  # well-known dir for all agent sockets
mkdir -p "$SOCKET_DIR"
SOCKET="$SOCKET_DIR/claude.sock"                # keep agent sessions separate from your personal tmux
SESSION=claude-python                           # slug-like names; avoid spaces
tmux -S "$SOCKET" new -d -s "$SESSION" -n shell
tmux -S "$SOCKET" send-keys -t "$SESSION":0.0 -- 'python3 -q' Enter
tmux -S "$SOCKET" capture-pane -p -J -t "$SESSION":0.0 -S -200  # watch output
tmux -S "$SOCKET" kill-session -t "$SESSION"                   # clean up
```

After starting a session, tell the user how to monitor the session by giving them a command to copy paste:

```
To monitor this session yourself:
  tmux -S "$SOCKET" attach -t claude-lldb

Or to capture the output once:
  tmux -S "$SOCKET" capture-pane -p -J -t claude-lldb:0.0 -S -200
```

## Socket convention

- Agents MUST place tmux sockets under `CLAUDE_TMUX_SOCKET_DIR` (defaults to `${TMPDIR:-/tmp}/claude-tmux-sockets`) and use `tmux -S "$SOCKET"` so we can enumerate/clean them. Create the dir first: `mkdir -p "$CLAUDE_TMUX_SOCKET_DIR"`.
- Default socket path to use unless you must isolate further: `SOCKET="$CLAUDE_TMUX_SOCKET_DIR/claude.sock"`.

## Targeting panes and naming

- Target format: `{session}:{window}.{pane}`, defaults to `:0.0` if omitted. Keep names short (e.g., `claude-py`, `claude-gdb`).
- Use `-S "$SOCKET"` consistently to stay on the private socket path. If you need user config, drop `-f /dev/null`; otherwise `-f /dev/null` gives a clean config.
- Inspect: `tmux -S "$SOCKET" list-sessions`, `tmux -S "$SOCKET" list-panes -a`.

## Finding sessions

- List sessions on your active socket with metadata: `./scripts/find-sessions.sh -S "$SOCKET"`; add `-q partial-name` to filter.
- Scan all sockets under the shared directory: `./scripts/find-sessions.sh --all` (uses `CLAUDE_TMUX_SOCKET_DIR` or `${TMPDIR:-/tmp}/claude-tmux-sockets`).

## Sending input safely

- Prefer literal sends to avoid shell splitting: `tmux -L "$SOCKET" send-keys -t target -l -- "$cmd"`
- When composing inline commands, use single quotes or ANSI C quoting to avoid expansion: `tmux ... send-keys -t target -- $'python3 -m http.server 8000'`.
- To send control keys: `tmux ... send-keys -t target C-c`, `C-d`, `C-z`, `Escape`, etc.

## Watching output

- Capture recent history (joined lines to avoid wrapping artifacts): `tmux -L "$SOCKET" capture-pane -p -J -t target -S -200`.
- For continuous monitoring, poll with the helper script (below) instead of `tmux wait-for` (which does not watch pane output).
- You can also temporarily attach to observe: `tmux -L "$SOCKET" attach -t "$SESSION"`; detach with `Ctrl+b d`.
- When giving instructions to a user, **explicitly print a copy/paste monitor command** alongside the action don't assume they remembered the command.

## Spawning Processes

Some special rules for processes:

- when asked to debug, use lldb by default
- when starting a python interactive shell, always set the `PYTHON_BASIC_REPL=1` environment variable. This is very important as the non-basic console interferes with your send-keys.

## Synchronizing / waiting for prompts

- Use timed polling to avoid races with interactive tools. Example: wait for a Python prompt before sending code:
  ```bash
  ./scripts/wait-for-text.sh -t "$SESSION":0.0 -p '^>>>' -T 15 -l 4000
  ```
- For long-running commands, poll for completion text (`"Type quit to exit"`, `"Program exited"`, etc.) before proceeding.

## Interactive tool recipes

- **Python REPL**: `tmux ... send-keys -- 'python3 -q' Enter`; wait for `^>>>`; send code with `-l`; interrupt with `C-c`. Always with `PYTHON_BASIC_REPL`.
- **gdb**: `tmux ... send-keys -- 'gdb --quiet ./a.out' Enter`; disable paging `tmux ... send-keys -- 'set pagination off' Enter`; break with `C-c`; issue `bt`, `info locals`, etc.; exit via `quit` then confirm `y`.
- **Other TTY apps** (ipdb, psql, mysql, node, bash): same pattern—start the program, poll for its prompt, then send literal text and Enter.

## Cleanup

- Kill a session when done: `tmux -S "$SOCKET" kill-session -t "$SESSION"`.
- Kill all sessions on a socket: `tmux -S "$SOCKET" list-sessions -F '#{session_name}' | xargs -r -n1 tmux -S "$SOCKET" kill-session -t`.
- Remove everything on the private socket: `tmux -S "$SOCKET" kill-server`.

## Helper: wait-for-text.sh

`./scripts/wait-for-text.sh` polls a pane for a regex (or fixed string) with a timeout. Works on Linux/macOS with bash + tmux + grep.

```bash
./scripts/wait-for-text.sh -t session:0.0 -p 'pattern' [-F] [-T 20] [-i 0.5] [-l 2000]
```

- `-t`/`--target` pane target (required)
- `-p`/`--pattern` regex to match (required); add `-F` for fixed string
- `-T` timeout seconds (integer, default 15)
- `-i` poll interval seconds (default 0.5)
- `-l` history lines to search from the pane (integer, default 1000)
- Exits 0 on first match, 1 on timeout. On failure prints the last captured text to stderr to aid debugging.