cmux Core Control

Non-browser cmux topology and routing.

• Window: top-level macOS cmux window.
• Workspace: tab-like group within a window.
• Pane: split container in a workspace.
• Surface: a tab within a pane (terminal or browser panel).

Fast start

cmux identify --json                              # current caller context
cmux list-windows / list-workspaces / list-panes
cmux list-pane-surfaces --pane pane:1
cmux new-workspace
cmux new-split right --panel pane:1
cmux new-split down --command "npm run dev"       # new terminal runs the command in a live shell
cmux move-surface --surface surface:7 --pane pane:2 --focus true
cmux split-off --surface surface:7 right
cmux reorder-surface --surface surface:7 --before surface:3

# workspace context-menu actions (color, description, rename, pin, ...)
cmux workspace-action --action set-color --color Blue
cmux workspace-action --action set-description --description "Ship checklist"

# attention cue
cmux trigger-flash --surface surface:7

Handle model

Output defaults to short refs (window:N, workspace:N, pane:N, surface:N). UUIDs are accepted as input; request UUID output only when needed with --id-format uuids|both.

Initial command on new terminals

new-workspace, new-split, new-pane, and new-surface accept --command <text>. cmux starts the terminal's normal interactive shell and delivers the text plus one Enter at spawn time, so the command runs immediately and the shell stays alive after it exits. No follow-up send or send-key enter is needed, and the text is passed literally (quoting, &&, pipes, and $VARS are interpreted by the new shell). The flag is terminal-only: it is rejected with --type browser|simulator|agent-session, blank text is ignored, and new-workspace --layout ignores it because layout surfaces define their own commands. Details: references/panes-surfaces.md.

Settings

cmux-owned settings live in ~/.config/cmux/cmux.json. cmux docs settings prints the docs URL, schema URL, raw GitHub resources, cmux.json paths, and reload command. cmux settings, cmux settings cmux-json, and cmux settings shortcuts open the UI.

cmux reload-config reloads both cmux.json and ~/.config/ghostty/config, refreshing terminals in place with no app restart.

Terminal rendering (font, cursor style, theme, scrollback, background-opacity, background-blur) belongs in Ghostty config, not cmux settings. Everything else (app behavior, sidebar, notifications, browser behavior, automation, workspace colors, cmux-owned shortcuts) is cmux settings. Before editing, copy any existing cmux.json to a timestamped .bak next to it. Legacy ~/.config/cmux/settings.json and ~/Library/Application Support/com.cmuxterm.app/settings.json are read only as fallback for missing keys.

Deep-dive references