rmux

A minimal terminal multiplexer built on libghostty-vt, the terminal emulation engine extracted from Ghostty. Client/server like tmux: a long-lived server owns sessions → tabs → panes, thin clients attach over a Unix socket — sessions survive SSH disconnects, reattach and everything is as you left it.

LLM agents get a first-class, non-interactive control surface — one-shot commands over the socket, no pty, no keystroke faking:

rmux agent new    build              # create an agent session (or: new build <tab>)
rmux agent send   build 'cargo test' # type text + Enter into it ([-t tab])
rmux agent read   build              # the rendered screen, as plain text ([-t tab])
rmux agent rename build tests        # short, descriptive names
rmux agent kill   build              # kill a session (or: kill build <tab>)

Agent sessions are sandboxed by design: the agent commands refuse to touch your sessions. They live in their own list, sorted by activity and tagged with a last-activity age — press a in the session manager to check on your agents, or attach with rmux a <name>; they are normal sessions underneath. A ready-made Claude Code skill ships in .claude/skills/rmux/.

Grab the latest Linux build for your architecture (x86_64 or aarch64) from the releases page and put rmux on your PATH:

tar xzf rmux-v*-$(uname -m)-linux.tar.gz && cd rmux-v*-$(uname -m)-linux
sudo install -m755 rmux /usr/local/bin/

Then run the server as a systemd system service — it starts at boot and survives SSH logouts, no linger tricks needed. The unit file ships in the tarball (and in this repo); set User= to your username first:

sudo cp rmux.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now rmux

To build from source instead: cargo install --path . — needs Rust 1.90+, plus Zig and git on PATH (libghostty-vt compiles from Ghostty source).

rmux a work    # attach to session "work", creating it if new
rmux list      # sessions: tabs, panes, attach state, agent ages

Detach with Ctrl+G (or drop the SSH connection — the session keeps running). The socket lives at /tmp/rmux-<uid>.sock (RMUX_SOCK overrides); server logs land in journalctl -u rmux. Run the server with --config <dir> to keep config.yaml and layout.json in a custom directory instead of ~/.config/rmux/.

~/.config/rmux/config.yaml — created from the built-in defaults on first run, and hot-reloaded within about a second of saving (a broken config is rejected and the old one stays active). Shown here with sample start_dir and commands values:

accent: "#7aa2f7"

shell: /usr/bin/bash

# where new shells start; unset or empty = your home directory
start_dir: ~/code

# lines of scrollback kept per pane
scrollback_lines: 5000

# mouse select-to-copy (clipboard via OSC 52, works over SSH)
select_copy: true

# tab bar position: bottom (default) or top
bar_position: bottom

terminal_envs:
  TERM: xterm-256color

# chords that type a program + Enter into the focused pane
commands:
  ctrl+h: htop
  ctrl+l: lazygit

keybindings:
  session-manager: ctrl+o
  tab-manager: ctrl+n
  split-horizontal: ctrl+w
  split-vertical: ctrl+q
  focus-next: ctrl+t
  focus-left: ctrl+h
  focus-right: ctrl+l
  focus-up: ctrl+k
  focus-down: ctrl+j
  detach: ctrl+g
  fullscreen: ctrl+f
  terminal-settings: ctrl+s

sessions:
  1: { name: project1, key: F1 }
  2: { name: project2, key: F2 }
  3: { name: random, key: F3 }

Keys are [ctrl+][alt+]<char> or F1–F12; every binding below is from this default config and can be remapped. Bound chords are swallowed by rmux and never reach the inner shell.

rmux does no terminal emulation of its own — that is all libghostty-vt, the VT engine from Ghostty. Credit for every correctly parsed escape sequence goes there.