just — A Handy Command Runner Written in Rust

Introduction

just is a pragmatic replacement for make when you don't actually need build-graph semantics — you just need a project-scoped command book. Where make treats every target as a filesystem artifact and punishes you for whitespace mistakes, just treats recipes as named shell commands with arguments, defaults, and interpolation that don't fight you.

What just Does

• Runs recipes defined in a justfile.
• Supports named arguments, defaults, dependencies between recipes.
• Evaluates shell per recipe (bash/zsh/pwsh configurable).
• Exports environment variables per recipe or globally.
• Lists recipes with just --list.

Architecture Overview

just parses the justfile into an AST of recipes and expressions, resolves the dependency graph (without timestamp semantics), and executes each recipe as a shell subprocess with interpolation applied. Variable assignment is lazy; set shell := ["bash", "-uc"] picks the interpreter.

Self-Hosting & Configuration

• Install via brew, cargo, scoop, winget, apt (snap), dnf.
• just --init bootstraps a justfile.
• Config block: set dotenv-load := true auto-loads .env.
• set windows-powershell := true flips to PowerShell on Windows.
• .justfile and justfile both recognized.

Key Features

• Clean recipe syntax with real arguments (not $1 hacks).
• Cross-platform: single binary for Linux/macOS/Windows.
• Dotenv autoloading.
• Per-recipe shebangs — write a recipe in Python or Node inline.
• just --choose opens fzf picker.

Comparison with Similar Tools

• make — universal; archaic syntax, tab-sensitive, filesystem-focused.
• npm scripts — Node-only; no arguments, no deps.
• task (go-task) — YAML-based; similar niche.
• mage — Go-based; requires Go.
• invoke (Python) — rich but Python-only.

FAQ

Q: Does it replace make for building C projects? A: No — use make for compilation. just is for workflow recipes.

Q: Can I call recipes from other recipes? A: Yes — recipeA: recipeB as dependency, or just recipeB inline.

Q: How about secrets? A: set dotenv-load + .env + gitignore.

Q: Windows without WSL? A: Yes, runs natively. Set set shell := ["pwsh.exe", "-c"].

Sources

• https://github.com/casey/just
• https://just.systems