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.

When to Reach for tmux

Default to tmux for any command that isn't a quick one-shot. If you know the command will:

•Produce streaming output you need to read and react to
•Ask for input, confirmations, or selections
•Take more than a few seconds and you want to check progress
•Run interactively (installers, wizards, watch-mode tools, test runners)

...then start it in tmux instead of blocking on bash. The workflow is:

•Start the command in a tmux session
•Check output with capture-pane periodically
•Interact — send input, respond to prompts, ctrl-c if needed
•Clean up the session when done

This is faster because you see partial output immediately, react to errors early, and never get stuck waiting for a blocking command to finish. You stay in control.

Don't use tmux for: quick one-shot commands (git status, ls, cat, grep), simple non-interactive CLIs, or file operations.

Quickstart (isolated socket)

bash

SOCKET_DIR=${TMPDIR:-/tmp}/pi-tmux-sockets  # well-known dir for all agent sockets
mkdir -p "$SOCKET_DIR"
SOCKET="$SOCKET_DIR/pi.sock"                # keep agent sessions separate from your personal tmux
SESSION=pi-python                           # slug-like names; avoid spaces
tmux -S "$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 ALWAYS tell the user how to monitor the session by giving them a ready-to-copy-paste command with the fully resolved absolute socket path — never use $SOCKET, $TMPDIR, or any variable. The user's shell may not have these set.

Example (adapt session name):

code

To monitor this session yourself:
  tmux -S /var/folders/xx/.../pi-tmux-sockets/pi.sock attach -t pi-lldb

This must ALWAYS be printed right after a session was started and once again at the end of the tool loop. But the earlier you send it, the happier the user will be.

Socket convention

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

Targeting panes and naming

•Target format: {session}:{window}.{pane}, defaults to :0.0 if omitted. Keep names short (e.g., pi-py, pi-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 PI_TMUX_SOCKET_DIR or ${TMPDIR:-/tmp}/pi-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.