rmux

A fast, minimal tmux-style multiplexer in Rust.

rmux uses Termy's embeddable terminal engine through the termy_core Git dependency. A background rmux server owns the session/window/pane model and the libtermy terminal surfaces for PTY startup, input, resize, event draining, and frame snapshots. The foreground process is a small TUI client over a Unix socket.

The libtermy runtime is initialized from the user's normal Termy config, so shell, TERM/COLORTERM environment, palette queries, cursor settings, scrollback, font metrics, and other runtime theme behavior follow the same local config Termy uses.

Install

With Bun (downloads and verifies a prebuilt binary for macOS/Linux):

bun install -g --trust @cookedoss/rmux
rmux

The --trust flag allows rmux's checksum-verifying installer to run. If Bun already installed rmux but blocked its postinstall script, run:

bun pm -g trust @cookedoss/rmux

With npm:

npm install -g @cookedoss/rmux
rmux

From source:

cargo install --path . --locked

Publishing a new npm version: bump the version, tag, and push. The Release workflow builds the platform binaries, attaches them to the GitHub release, and publishes npm/ to the registry (requires the NPM_TOKEN repo secret).

git tag v0.1.0 && git push origin v0.1.0

Run

cargo run

Start the first pane with a command:

cargo run -- --command "top"

Start or attach with tmux-shaped commands:

cargo run -- new-session -s work -c "zsh"
cargo run -- new-session -d -s worker -c "top"
cargo run -- new-session -A -s work -c "zsh"
cargo run -- new-session -d -P -F "#{session_name}:#{window_id}.#{pane_id}" -s worker
cargo run -- attach -t work
cargo run -- attach -t work:logs.1
cargo run -- list-sessions
cargo run -- list-sessions -F "#{session_name}:#{window_count}"
cargo run -- source-file ./rmux.conf
cargo run -- has-session -t work
cargo run -- wait-for -t work
cargo run -- send-keys -t work "echo hello from rmux" Enter
cargo run -- send-keys -t work --literal "literal Enter"
cargo run -- send-prefix -t work
cargo run -- wait-for -t work "hello from rmux"
cargo run -- capture-pane -t work
cargo run -- capture-pane --all-panes -t work
cargo run -- display-message -t work -p "#{session_name}:#{window_index}.#{pane_index}"
cargo run -- set-option -t work default-command "zsh"
cargo run -- display-message -t work -p "#{default_command}"
cargo run -- set-option -t work prefix C-a
cargo run -- display-message -t work -p "#{prefix_key}"
cargo run -- bind-key -t work v split-window --horizontal
cargo run -- list-keys -t work
cargo run -- split-window -t work --horizontal -c "htop"
cargo run -- split-window -t work -P -F "#{pane_id}"
cargo run -- list-panes -t work
cargo run -- list-panes -t work -F "#{pane_index}:#{pane_id}"
cargo run -- list-panes -t work -F "#{pane_index}:#{pane_active}:#{pane_width}x#{pane_height}"
cargo run -- next-pane -t work
cargo run -- previous-pane -t work
cargo run -- select-pane -t work 1
cargo run -- select-layout -t work even-vertical
cargo run -- resize-pane -t work -R 5
cargo run -- swap-pane -t work -D
cargo run -- break-pane -t work:1.2 -n broken
cargo run -- break-pane -t work:1.2 -P -F "#{window_name}:#{pane_id}"
cargo run -- join-pane -s work:broken.1 -t work:1
cargo run -- join-pane -s work:broken.1 -t work:1 -P -F "#{window_index}:#{pane_id}"
cargo run -- set-window-option -t work synchronize-panes on
cargo run -- display-message -t work -p "#{synchronize_panes}"
cargo run -- send-keys -t work:1.2 "echo sent to pane 2" Enter
cargo run -- capture-pane -t work:1.2
cargo run -- new-window -t work -n logs -c "tail -f /var/log/system.log"
cargo run -- new-window -t work -P -F "#{window_id}:#{pane_id}"
cargo run -- display-message -t work:logs.1 -p "#{window_name}:#{pane_index}"
cargo run -- display-message -t 'work:#2.%3' -p "#{window_name}:#{pane_id}"
cargo run -- next-window -t work
cargo run -- previous-window -t work
cargo run -- last-window -t work
cargo run -- swap-window -t work -U
cargo run -- move-window -t work 1
cargo run -- rename-window -t work editor
cargo run -- rename-session -t work client-a
cargo run -- list-windows -t work
cargo run -- list-windows -t work -F "#{window_index}:#{window_name}"
cargo run -- list-windows -t work -F "#{window_index}:#{window_active}:#{window_name}"
cargo run -- kill-window -t work
cargo run -- kill-pane -a -t work
cargo run -- respawn-pane -t work:1.1 -c "zsh"
cargo run -- respawn-window -t work:logs -c "zsh"
cargo run -- detach-client -t work
cargo run -- kill-session -t work
cargo run -- kill-server

Sessions run in a single-machine background server. Ctrl-b d detaches the UI while the server keeps the session alive; attach reconnects to an existing server session.

Keys

• Ctrl-b | splits horizontally.
• Ctrl-d splits horizontally without the prefix.
• Ctrl-Shift-d splits vertically without the prefix.
• Cmd-d and Cmd-Shift-d also work when the terminal forwards the macOS command modifier.
• Ctrl-t creates a new window/tab, not a pane.
• Ctrl-1 through Ctrl-9 selects a window/tab (requires terminal support; use Alt-1–Alt-9 or Ctrl-b 1–Ctrl-b 9 if your terminal doesn't forward Ctrl+digit).
• Alt-1 through Alt-9 selects a window/tab (works in most terminals).
• Ctrl-w closes the active pane, except the last pane.
• Click inside a pane to select it.
• Drag across terminal text to select and copy it to the system clipboard.
• Use the mouse wheel to move through scrollback. Hold Shift while dragging or scrolling to override an application's mouse capture.
• Ctrl-b Ctrl-b sends a literal prefix key to the pane.
• set-option prefix C-a changes the prefix key for that session.
• bind-key v split-window --horizontal binds a custom prefix action.
• Ctrl-b - splits vertically.
• Ctrl-b n or Ctrl-b Right selects the next pane.
• Ctrl-b p or Ctrl-b Left selects the previous pane.
• Ctrl-b Space toggles between even-horizontal and even-vertical layouts.
• Ctrl-b H/J/K/L resizes the active pane left/down/up/right.
• Ctrl-b { and Ctrl-b } swaps the active pane with the previous or next pane.
• Ctrl-b x kills the active pane, except the last pane.
• Ctrl-b c creates a window.
• Ctrl-b 1 through Ctrl-b 9 selects a window.
• Ctrl-b l selects the previously active window.
• Ctrl-b d detaches the UI process.
• Ctrl-b q quits.

Check

cargo fmt --check
cargo clippy --locked --all-targets -- -D warnings
cargo test
cargo run -- --help
node --test npm/install.test.js
./scripts/smoke-detach-attach.sh