tmux-terminal

Overview

Use tmux to drive interactive terminal sessions, including TUI workflows like ralph-tui. tmux lets you send keystrokes, capture screen output, and keep processes running between steps.

When to Use

Testing ralph-tui or any interactive CLI prompts
Managing long-running processes (web server, loops, watch mode)
Capturing live terminal output for QA reports
Interacting with applications that redraw the screen

Prerequisites

tmux installed (pre-installed on macOS)

Verify:

tmux -V

Core Commands

Create a detached session:

tmux new-session -d -s <name>

Send commands (append Enter to execute):

tmux send-keys -t <name> "<command>" Enter

Capture screen output:

tmux capture-pane -t <name> -p

Kill session when done:

tmux kill-session -t <name>

Special Keys

Use send-keys with key names:

Enter
C-c (Ctrl-C)
C-d (Ctrl-D)
Tab
Escape
Up, Down, Left, Right

Examples:

tmux send-keys -t <name> Up
tmux send-keys -t <name> C-c

TUI Interaction Patterns

Start ralph-tui

tmux new-session -d -s ralph-tui
tmux send-keys -t ralph-tui "cargo run -p ralph-tui" Enter

Navigate in TUI

tmux send-keys -t ralph-tui Down
tmux send-keys -t ralph-tui Enter

Capture and parse the screen

tmux capture-pane -t ralph-tui -p -S -200

Use -S -200 to capture the last 200 lines when the screen is noisy.

Long-Running Process Management

Start servers or loops in a tmux session to keep them alive.
Use capture-pane to confirm health (look for "listening" or "ready" text).
Stop cleanly with C-c then kill-session.

Example:

tmux new-session -d -s ralph-web
tmux send-keys -t ralph-web "cargo run -p ralph-cli -- web" Enter
tmux capture-pane -t ralph-web -p | rg -n "listening|ready"
tmux send-keys -t ralph-web C-c
tmux kill-session -t ralph-web

Notes

Keep session names short and unique.
Always clean up sessions to avoid leaking background processes.
If output looks empty, wait briefly and capture again.