Muxrun

muxrun

/mʌks.rʌn/

Managing multiple processes across terminals gets messy: scattered tabs, no clear picture of what's running where, and manual restarts every time you switch branches or worktrees.

muxrun keeps it simple — muxrun up to start everything, muxrun ps to see what's running and from which directory, muxrun up again to restart.

Quick Start

1. Install muxrun:

Homebrew (macOS / Linux):

brew install --cask tkuramot/tap/muxrun

Or via go install:

go install github.com/tkuramot/muxrun@latest

1. Create muxrun.toml in your project directory:

[[group]]
name = "myapp"
dir = "."

  [[group.app]]
  name = "server"
  cmd = "go run main.go"

1. Run:

muxrun up

This starts the server app inside a tmux session named muxrun-myapp. Use muxrun down to stop it.

Overview

muxrun organizes applications into groups. Each group becomes a tmux session, and each app becomes a window within that session.

muxrun
├── Group A (tmux session)
│   ├── App 1 (tmux window)
│   └── App 2 (tmux window)
└── Group B (tmux session)
    └── App 3 (tmux window)

Requirements

• tmux 3.0+

Configuration

Config file resolution

muxrun looks for a config file in the following order:

1. --config / -c flag (explicit path, skips other lookup)
2. muxrun.toml in the current directory, then parent directories up to the filesystem root

Minimal example

[[group]]
name = "backend"
dir = "."

  [[group.app]]
  name = "api"
  cmd = "go run main.go"

Full example with file watching

[[group]]
name = "backend"
dir = "."

  [[group.app]]
  name = "api"
  cmd = "go run main.go"
  watch = { enabled = true, exclude = ["_test\\.go$"] }

  [[group.app]]
  name = "worker"
  cmd = "go run worker.go"

[[group]]
name = "frontend"
dir = "./frontend"

  [[group.app]]
  name = "dev"
  cmd = "npm run dev"

Fields

See docs/config.md for the full field reference, watch configuration, and validation rules.

When watch is enabled, muxrun starts a background daemon that restarts the app on file changes. The daemon starts with muxrun up and stops with muxrun down.

Usage

muxrun up — Start applications

muxrun up                           # Start all groups
muxrun up backend                   # Start a specific group
muxrun up backend frontend          # Start multiple groups

muxrun down — Stop applications

down accepts the same arguments as up.

muxrun down                         # Stop all groups
muxrun down backend                 # Stop a specific group

[!WARNING] Use muxrun down to stop sessions. Killing sessions directly with tmux kill-session may leave file watch daemons running.

muxrun ps — Check status

$ muxrun ps
GROUP       APP       STATUS    PID      DIR
backend     api       running   12345    /home/user/repo/cmd/api
backend     worker    running   12346    /home/user/repo/cmd/worker
frontend    dev       stopped   -        /home/user/repo/frontend

muxrun logs — View pane output

muxrun logs backend api       # Show buffered output for an app
muxrun logs -f backend api    # Stream output in real-time (Ctrl-C to stop)

[!TIP] If you're familiar with tmux, each app runs in its own window inside a muxrun-<group> session — attach directly for full scrollback and search.

muxrun check — Validate config file

muxrun check

Tips

Using with git worktrees

When dir is a relative path, it is resolved relative to the muxrun.toml location. Copy muxrun.toml into each worktree at creation time to treat each worktree as an independent environment.

[[group]]
name = "backend"
dir = "."          # resolved relative to muxrun.toml location

  [[group.app]]
  name = "api"
  cmd = "go run main.go"

With the same group name across worktrees, running muxrun up always restarts the apps for the current worktree — even if the session is already running from a different one:

# working in worktree-A
cd ~/repo-worktree-A && muxrun up   # muxrun-backend starts in A

# switch to worktree-B
cd ~/repo-worktree-B && muxrun up   # same session restarts in B

Copying muxrun.toml on worktree creation can be automated with a post-checkout hook or a worktree management tool like git-worktree-runner.

Claude Code Plugin

If you use Claude Code, you can install the muxrun plugin to author and operate muxrun.toml with skills.

Install

Run these inside Claude Code:

/plugin marketplace add tkuramot/muxrun
/plugin install muxrun@muxrun

The first command registers this repo as a marketplace; the second installs the muxrun plugin from it. Update later with /plugin marketplace update muxrun.

Skills

Skill	Description
/muxrun-init	Analyze your project structure and generate a tailored muxrun.toml
/muxrun-import-compose	Convert an existing docker-compose.yml / Procfile into muxrun.toml
/muxrun-doctor	Diagnose tmux/daemon/PID/config issues in the local environment
/muxrun-triage-failure	Find failing apps via muxrun ps, fetch logs, and pinpoint the cause
/muxrun-tail	Follow an app's logs and surface anomalies (panics, 5xx, restart loops)
/muxrun-perf	Diagnose slow startup / restart storms / over-broad watch and tune exclude
/muxrun-bisect	Drive git bisect for runtime regressions reproducible only with the dev stack up

Shell Completion

muxrun supports tab completion for zsh. Subcommands, flags, and group names are completed dynamically.

eval "$(muxrun completion zsh)"

To make it persistent, add the line to ~/.zshrc.

Development

go test ./...                        # Unit tests
go test -tags=integration ./...      # Integration tests
go test -tags=e2e ./...              # E2E tests

License

MIT