tmux

tmux Skill

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

Quickstart (isolated socket)

SOCKET_DIR="${OPC_TMUX_SOCKET_DIR:-${TMPDIR:-/tmp}/opc-tmux-sockets}"
mkdir -p "$SOCKET_DIR"
SOCKET="$SOCKET_DIR/opc.sock"
SESSION=opc-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 OPC_TMUX_SOCKET_DIR environment variable.
• Default socket path: "$OPC_TMUX_SOCKET_DIR/opc.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 OPC_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).

Orchestrating Coding Agents

tmux excels at running multiple coding agents in parallel:

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

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

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

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

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