Tmux Skill

This skill empowers you to manage multiple concurrent processes (like servers, watchers, or long builds) using tmux directly from the Bash tool.

Since you are likely already running inside a tmux session, you can spawn new windows or panes to handle these tasks without blocking your main communication channel.

1. Verify Environment & Check Status

First, verify you are running inside tmux:

echo $TMUX

If this returns empty, you are not running inside tmux and these commands will not work as expected.

Once verified, check your current windows:

tmux list-windows

2. Spawn a Background Process

To run a command (e.g., a dev server) in a way that persists and can be inspected:

1. Create a new detached window with a specific name. This keeps it isolated and easy to reference.

   bashCopy

   tmux new-window -n "server-log" -d
   

   (Replace "server-log" with a relevant name for your task)

2. Send the command to that window.

   bashCopy

   tmux send-keys -t "server-log" "npm start" C-m
   

   (C-m simulates the Enter key)

3. Inspect Output (Read Logs)

You can read the output of that pane at any time without switching your context.

Get the current visible screen:

tmux capture-pane -p -t "server-log"

Get the entire history (scrollback):

tmux capture-pane -p -S - -t "server-log"

Use this if the output might have scrolled off the screen.

4. Interact with the Process

If you need to stop or restart the process:

Send Ctrl+C (Interrupt):

tmux send-keys -t "server-log" C-c

Kill the window (Clean up):

tmux kill-window -t "server-log"

5. Advanced: Chaining Commands

You can chain multiple tmux commands in a single invocation using ';' (note the quotes to avoid interpretation by the shell). This is faster and cleaner than running multiple tmux commands.

Example: Create window and start process in one go:

tmux new-window -n "server-log" -d ';' send-keys -t "server-log" "npm start" C-m

Summary of Pattern

1. tmux new-window -n "ID" -d
2. tmux send-keys -t "ID" "CMD" C-m
3. tmux capture-pane -p -t "ID"

6. Multi-Model Fan Out Pattern

Used when you want to get perspectives from multiple AI models in parallel (e.g., GPT-5.2, Gemini Pro).

Setup

# Kill existing session, create new with multiple windows
tmux kill-session -t model-consult 2>/dev/null
tmux new-session -d -s model-consult -n gpt5 ';' new-window -t model-consult -n gemini

Send Queries

Use heredoc to avoid quote escaping issues:

tmux send-keys -t model-consult:gpt5 'cat <<EOF | opencode run --model openai/gpt-5.2 -
Your prompt here
EOF
echo ###DONE###' C-m

Poll for Completion

tmux capture-pane -p -S - -t model-consult:gpt5 | tail -50
# Look for ###DONE### marker

Poll every ~10 seconds. Queries typically take 2-5 minutes.

Capture Full Output

tmux capture-pane -p -S - -t model-consult:gpt5

The -S - flag captures full scrollback history, not just visible screen.

Cleanup

tmux kill-session -t model-consult

Model Aliases Reference

Run opencode models for full list.

Key Learnings

1. USE HEREDOC (cat <<EOF) to avoid quote escaping nightmares
2. ADD ###DONE### marker to know when query completes
3. USE -S - flag with capture-pane to get full scrollback
4. POLL every 10 seconds - queries can take 2-5 minutes