Just — A Modern Command Runner and Makefile Alternative

What Just Does

• Recipes — named task definitions in a justfile
• Arguments — positional and named with defaults
• Dependencies — recipes can depend on other recipes
• Shebang recipes — run entire recipe with python/node/bash
• String interpolation — {{var}} substitution
• Env vars — dotenv support via set dotenv-load
• Conditional — if os == "macos" { ... }
• Private recipes — prefix with _
• Groups — organize recipes into groups

Architecture

Parses the justfile, builds a DAG of recipes, and runs them via the configured shell (sh by default, or any shebang). No make-style file timestamps or incremental logic — simpler and more predictable.

Self-Hosting

Single Rust binary.

Key Features

• Modern clean syntax
• Cross-platform (macOS, Linux, Windows)
• Recipe arguments with defaults
• Dependencies and groups
• Shebang recipes for multi-language tasks
• Env var integration
• Nice error messages
• just --list auto-help
• Tab or space indentation

Comparison

FAQ

Q: How does it differ from Make? A: Just doesn't do incremental builds (no file-timestamp tracking) — it focuses on task running. The syntax is cleaner: no mandatory tabs, no .PHONY pitfalls. Great for project tasks, not for large C/C++ builds.

Q: Can it be used in CI? A: It's a great fit. In CI, just ci runs all checks in one line — and developers get exactly the same experience locally.

Q: Does it support include? A: Yes — import syntax (v1.14+) lets you reuse recipes.

Sources & Credits

• Docs: https://just.systems
• GitHub: https://github.com/casey/just
• License: CC0