tmux Skill (Otto)

Use tmux only when you need an interactive TTY. Prefer exec background mode for long-running, non-interactive tasks.

Quickstart (isolated socket, exec tool)

SOCKET_DIR="${OTTO_TMUX_SOCKET_DIR:-${TMPDIR:-/tmp}/otto-tmux-sockets}" mkdir -p "$SOCKET_DIR" SOCKET="$SOCKET_DIR/otto.sock" SESSION=otto-python

tmux -S "$SOCKET" new -d -s "$SESSION" -n shell tmux -S "$SOCKET" send-keys -t "$SESSION":0.0 -- 'PYTHON_BASIC_REPL=1 python3 -q' Enter tmux -S "$SOCKET" capture-pane -p -J -t "$SESSION":0.0 -S -200

After starting a session, always print monitor commands:

To monitor: tmux -S "$SOCKET" attach -t "$SESSION" tmux -S "$SOCKET" capture-pane -p -J -t "$SESSION":0.0 -S -200

Socket convention

• Use OTTO_TMUX_SOCKET_DIR .

• Default socket path: "$OTTO_TMUX_SOCKET_DIR/otto.sock" .

Targeting panes and naming

• Target format: session:window.pane (defaults to :0.0 ).

• Keep names short; avoid spaces.

• Inspect: tmux -S "$SOCKET" list-sessions , tmux -S "$SOCKET" list-panes -a .

Finding sessions

• List sessions on your socket: {baseDir}/scripts/find-sessions.sh -S "$SOCKET" .

• Scan all sockets: {baseDir}/scripts/find-sessions.sh --all (uses OTTO_TMUX_SOCKET_DIR ).

Sending input safely

• Prefer literal sends: tmux -S "$SOCKET" send-keys -t target -l -- "$cmd" .

• Control keys: tmux -S "$SOCKET" send-keys -t target C-c .

• For interactive TUI apps like Claude Code/Codex, this guidance covers how to send commands. Do not append Enter in the same send-keys . These apps may treat a fast text+Enter sequence as paste/multi-line input and not submit; this is timing-dependent. Send text and Enter as separate commands with a small delay (tune per environment; increase if needed, or use sleep 1 if sub-second sleeps aren't supported):

tmux -S "$SOCKET" send-keys -t target -l -- "$cmd" && sleep 0.1 && tmux -S "$SOCKET" send-keys -t target Enter

Watching output

• Capture recent history: tmux -S "$SOCKET" capture-pane -p -J -t target -S -200 .

• Wait for prompts: {baseDir}/scripts/wait-for-text.sh -t session:0.0 -p 'pattern' .

• Attaching is OK; detach with Ctrl+b d .

Spawning processes

• For python REPLs, set PYTHON_BASIC_REPL=1 (non-basic REPL breaks send-keys flows).

Windows / WSL

• tmux is supported on macOS/Linux. On Windows, use WSL and install tmux inside WSL.

• This skill is gated to darwin /linux and requires tmux on PATH.

Orchestrating Coding Agents (Codex, Claude Code)

tmux excels at running multiple coding agents in parallel:

SOCKET="${TMPDIR:-/tmp}/codex-army.sock"

Create multiple sessions

for i in 1 2 3 4 5; do tmux -S "$SOCKET" new-session -d -s "agent-$i" done

Launch agents in different workdirs

tmux -S "$SOCKET" send-keys -t agent-1 "cd /tmp/project1 && codex --yolo 'Fix bug X'" Enter tmux -S "$SOCKET" send-keys -t agent-2 "cd /tmp/project2 && codex --yolo 'Fix bug Y'" Enter

When sending prompts to Claude Code/Codex TUI, split text + Enter with a delay

tmux -S "$SOCKET" send-keys -t agent-1 -l -- "Please make a small edit to README.md." && sleep 0.1 && tmux -S "$SOCKET" send-keys -t agent-1 Enter

Poll for completion (check if prompt returned)

for sess in agent-1 agent-2; do if tmux -S "$SOCKET" capture-pane -p -t "$sess" -S -3 | grep -q "❯"; then echo "$sess: DONE" else echo "$sess: Running..." fi done

Get full output from completed session

tmux -S "$SOCKET" capture-pane -p -t agent-1 -S -500

Tips:

• Use separate git worktrees for parallel fixes (no branch conflicts)

• pnpm install first before running codex in fresh clones

• Check for shell prompt (❯ or $ ) to detect completion

• Codex needs --yolo or --full-auto for non-interactive fixes

Cleanup

• Kill a session: 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

{baseDir}/scripts/wait-for-text.sh polls a pane for a regex (or fixed string) with a timeout.

{baseDir}/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 (integer, default 1000)