Just Command Runner

GitHub Repository

just is a handy way to save and run project-specific commands. It's a command runner, not a build system, avoiding much of make's complexity.

Instructions

Prerequisites

• just must be installed: brew install just
• Commands are stored in a justfile (or Justfile).

Common Settings (set ...)

You can configure just behavior at the top of your justfile:

• set shell := ["bash", "-c"]: Change the default shell.
• set dotenv-load: Automatically load .env files.
• set allow-duplicate-recipes: Allow overriding recipes.
• set fallback: Search for justfile in parent directories.
• set quiet: Don't echo commands by default.

Example Justfiles

For complete reference, see these templates:

• [Node.js + Docker](examples/node-docker.just)
• [Python + Venv](examples/python-venv.just)
• [Bun + TypeScript](examples/bun-typescript.just)
• [Astral UV + Python](examples/uv-python.just)
• [Multi-Module / Advanced](examples/multi-module.just)

Workflow

1. Create a justfile:

Define recipes at the top level of your project. Always include a default recipe that lists available commands: ``just default: @just --list ` `just # The default recipe (runs when calling just` with no args) default: just --list

# A basic recipe test: cargo test

# A recipe with parameters build target: echo "Building {{target}}..." cc main.c -o {{target}} ```

1. Run Recipes:

- Run the default recipe: just - Run a specific recipe: just <recipe> - Pass arguments to a recipe: just build my-app - List all available recipes: just --list

1. Advanced Features:

- Dependencies: test: build (runs build before test). - Shebang Recipes: Use other languages like Python or Node inside a recipe. ``just python-task: #!/usr/bin/env python3 print("Hello from Python!") ` - Dotenv: set dotenv-load at the top of the file to load .env`.

Examples

Example 1: Standard Development Justfile

User request:

Create a justfile for my Node project to handle lint, test, and dev

You would:

1. Create a justfile:

```just default: @just --list

lint: npm run lint

test: npm test

dev: npm run dev ```

1. Tell the user they can now run just dev or just test.

Example 2: Recipe with Parameters

User request:

Add a recipe to just to deploy to a specific environment

You would:

1. Edit the justfile:

``just deploy env: echo "Deploying to {{env}}..." ./scripts/deploy.sh --target {{env}} ``

1. Inform the user they can run just deploy production.

Example 3: Listing Recipes

User request:

What commands are available in this project?

You would:

1. Run just --list to see available recipes and their comments.