How do I pass arguments to a Just recipe?

Define recipes with parameters using {{}} syntax, e.g., `build {{project}}`, and pass values from the command line like `just build myapp`. This allows for dynamic and reusable scripts, as detailed in the recipe parameters section.

Just vs make: which should I use?

Just is better for simple command running and cross-platform task automation with cleaner syntax, while make excels at complex build systems with dependency tracking. Choose Just for development workflows and Make for intricate compilation processes.

Can I run Just from any subdirectory?

Yes, Just automatically searches parent directories for a justfile, so you can invoke recipes from any subdirectory without specifying the file path. This is a key feature mentioned in the README for flexibility.

How to write a Just recipe in Python?

Use a shebang line at the start of the recipe, e.g., `#!/usr/bin/env python3`, followed by Python code. Just will execute it using the specified interpreter, supporting arbitrary languages as described.

Does Just load environment variables from .env files?

Yes, enable it with `set dotenv-load` in your justfile, and Just will automatically load variables from a .env file in the working directory, making configuration management easier for projects.

Is Just available on Windows without installing Git?

It can be, but you need to configure the shell explicitly. Set `shell := ['powershell.exe', '-c']` to use PowerShell, or use cmd.exe, though the default requires sh from Git for Windows, which might be a barrier.

Open-Awesome

just

CC0-1.0Rust1.58.0

A command runner for saving and running project-specific commands with a simple, make-inspired syntax.

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35.7k stars838 forks0 contributors

What is just?

Just is a command-line tool that allows developers to define and run project-specific commands (called recipes) from a simple configuration file called a `justfile`. It solves the problem of managing repetitive tasks, scripts, and workflows in a project by providing a clean, cross-platform alternative to tools like `make`. Just focuses on being a command runner rather than a full build system, avoiding unnecessary complexity.

Target Audience

Developers and teams working on software projects who need a reliable, simple way to automate tasks like building, testing, deploying, or running scripts across different environments.

Value Proposition

Developers choose Just over alternatives like `make` because it offers a more intuitive syntax, better error messages, cross-platform support out of the box, and modern features like `.env` file loading and recipe arguments—all while being specifically designed as a command runner to avoid the pitfalls of traditional build systems.

Overview

🤖 Just a command runner

Use Cases

Best For

Automating repetitive development tasks like building, testing, and deployment
Managing project-specific scripts in a version-controlled `justfile`
Replacing complex `make` files with a simpler, more maintainable alternative
Running cross-platform scripts consistently on Linux, macOS, and Windows
Organizing and documenting project workflows with clear recipe names and comments
Loading environment variables from `.env` files for configuration management

Not Ideal For

Projects requiring incremental build systems with fine-grained dependency tracking, such as large C++ codebases where make or CMake are standard.
Environments where advanced shell scripting or non-POSIX shell features are essential, as Just's default shell may not support all edge cases without complex configuration.
Teams already using mature ecosystem-specific task runners like npm scripts for Node.js projects, where switching adds little value and could disrupt existing workflows.
Use cases demanding interactive or GUI-based task execution, since Just is purely command-line oriented and lacks built-in support for user interfaces.

Pros & Cons

Pros

Clean, Make-Inspired Syntax

Just eliminates the need for .PHONY declarations and uses a straightforward syntax, making justfiles more readable and maintainable than traditional makefiles, as highlighted in the README's focus on simplicity.

Cross-Platform Compatibility

Runs on Linux, macOS, and Windows with minimal setup by leveraging available shells or configurable alternatives, ensuring consistent task execution across environments without additional dependencies.

Modern Development Features

Supports recipe parameters, automatic .env file loading, and shell completion scripts, streamlining common development workflows and configuration management, as evidenced by the rich feature set described.

Static Error Checking

Reports errors like unknown recipes and circular dependencies before execution, providing specific and informative messages that help catch issues early, improving reliability over runtime failures.

Cons

Not a Full Build System

As a command runner, Just lacks advanced build features such as incremental compilation or complex dependency resolution, making it unsuitable for projects that require these capabilities, which the README acknowledges by positioning it against tools like make.

Windows Shell Configuration Hurdles

On Windows, Just defaults to requiring an sh shell from Git for Windows or similar, and configuring alternative shells like PowerShell requires explicit settings in the justfile, which can be confusing for users unfamiliar with shell paths.

Smaller Ecosystem and Tooling

Compared to established alternatives like make or npm scripts, Just has fewer community resources, pre-built justfiles, and third-party integrations, potentially limiting support and examples for complex use cases.

Open Source Alternative To

just is an open-source alternative to the following products:

make

Make (or GNU Make) is a build automation tool that automatically builds executable programs and libraries from source code by reading Makefiles.

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