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

• Python + Venv

• Bun + TypeScript

• Astral UV + Python

• Multi-Module / Advanced

Workflow

Create a justfile : Define recipes at the top level of your project. Always include a default recipe that lists available commands:

default: @just --list

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}}

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

Advanced Features:

• Dependencies: test: build (runs build before test ).

• Shebang Recipes: Use other languages like Python or Node inside a recipe. 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:

• Create a justfile : default: @just --list

lint: npm run lint

test: npm test

dev: npm run dev

• 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:

• Edit the justfile : deploy env: echo "Deploying to {{env}}..." ./scripts/deploy.sh --target {{env}}

• Inform the user they can run just deploy production .

Example 3: Listing Recipes

User request:

What commands are available in this project?

You would:

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