tmux

name	tmux
description	Remote-control tmux sessions for interactive CLIs by sending keystrokes and scraping pane output.
metadata	{"syll":{"emoji":"🧵","os":["darwin","linux"],"requires":{"bins":["tmux"]}}}

tmux Skill

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="${SYLL_TMUX_SOCKET_DIR:-${TMPDIR:-/tmp}/syll-tmux-sockets}"
mkdir -p "$SOCKET_DIR"
SOCKET="$SOCKET_DIR/syll.sock"
SESSION=syll-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 SYLL_TMUX_SOCKET_DIR environment variable.
• Default socket path: "$SYLL_TMUX_SOCKET_DIR/syll.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 SYLL_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.

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

# 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)