Expert knowledge for Just command runner, recipe development, and task automation with focus on cross-platform compatibility and project standardization.

Core Expertise

Command Runner Mastery

Justfile syntax and recipe structure
Cross-platform task automation (Linux, macOS, Windows)
Parameter handling and argument forwarding
Module organization for large projects

Recipe Development Excellence

Recipe patterns for common operations
Dependency management between recipes
Shebang recipes for complex logic
Environment variable integration

Project Standardization

Standard recipes for consistent workflows
Self-documenting project operations
Portable patterns across projects
Integration with CI/CD pipelines

Key Capabilities

Recipe Parameters

Required parameters: recipe param: - must be provided
Default values: recipe param="default": - optional with fallback
Variadic +: recipe +FILES: - one or more arguments
Variadic *: recipe *FLAGS: - zero or more arguments
Environment export: recipe $VAR: - parameter as env var

Settings Configuration

set dotenv-load: Load .env file automatically
set positional-arguments: Enable $1, $2 syntax
set export: Export all variables as env vars
set shell: Custom shell interpreter
set quiet: Suppress command echoing

Recipe Attributes

[private]: Hide from --list output
[no-cd]: Don't change directory
[no-exit-message]: Suppress exit messages
[unix] / [windows]: Platform-specific recipes
[positional-arguments]: Per-recipe positional args

Module System

mod name: Declare submodule
mod name 'path': Custom module path
Invocation: just module::recipe or just module recipe

Essential Syntax

Basic Recipe Structure

# Comment describes the recipe
recipe-name:
    command1
    command2

Recipe with Parameters

build target:
    @echo "Building {{target}}..."
    cd {{target}} && make

test *args:
    uv run pytest {{args}}

Recipe Dependencies

default: build test

build: _setup
    cargo build --release

_setup:
    @echo "Setting up..."

Variables and Interpolation

version := "1.0.0"
project := env('PROJECT_NAME', 'default')

info:
    @echo "Project: {{project}} v{{version}}"

Conditional Recipes

[unix]
open:
    xdg-open http://localhost:8080

[windows]
open:
    start http://localhost:8080

Standard Recipes

Every project should provide these standard recipes:

# Justfile - Project task runner
# Run `just` or `just help` to see available recipes

set dotenv-load
set positional-arguments

# Default recipe - show help
default:
    @just --list

# Show available recipes with descriptions
help:
    @just --list --unsorted

####################
# Development
####################

# Run linters
lint:
    # Language-specific lint command

# Format code
format:
    # Language-specific format command

# Run tests
test *args:
    # Language-specific test command {{args}}

# Development mode with watch
dev:
    # Start with file watching

####################
# Build & Deploy
####################

# Build project
build:
    # Build command

# Clean build artifacts
clean:
    # Cleanup command

# Start service
start:
    # Start command

# Stop service
stop:
    # Stop command

Common Patterns

Setup/Bootstrap Recipe

# Initial project setup
setup:
    #!/usr/bin/env bash
    set -euo pipefail
    echo "Installing dependencies..."
    uv sync
    echo "Setting up pre-commit..."
    pre-commit install
    echo "Done!"

Docker Integration

# Build container image
docker-build tag="latest":
    docker build -t {{project}}:{{tag}} .

# Run container
docker-run tag="latest" *args:
    docker run --rm -it {{project}}:{{tag}} {{args}}

# Push to registry
docker-push tag="latest":
    docker push {{registry}}/{{project}}:{{tag}}

Database Operations

# Run database migrations
db-migrate:
    uv run alembic upgrade head

# Create new migration
db-revision message:
    uv run alembic revision --autogenerate -m "{{message}}"

# Reset database
db-reset:
    uv run alembic downgrade base
    uv run alembic upgrade head

CI/CD Recipes

# Full CI check (lint + test + build)
ci: lint test build
    @echo "CI passed!"

# Release workflow
release version:
    git tag -a "v{{version}}" -m "Release {{version}}"
    git push origin "v{{version}}"

Best Practices

Recipe Development Workflow

Name clearly: Use descriptive, verb-based names (build, test, deploy)
Document always: Add comment before each recipe
Use defaults: Provide sensible default parameter values
Group logically: Organize with section comments
Hide internals: Mark helper recipes as [private]
Test portability: Verify on all target platforms

Critical Guidelines

Always provide default recipe pointing to help
Use @ prefix to suppress command echo when appropriate
Use shebang recipes for multi-line logic
Prefer set dotenv-load for configuration
Use modules for large projects (>20 recipes)
Include variadic *args for passthrough flexibility
Quote all variables in shell commands

Comparison with Alternatives

| Syntax | Simple, clear | Complex, tabs required | YAML

| Dependencies | Built-in | Built-in | Manual

| Parameters | Full support | Limited | Full support

| Cross-platform | Excellent | Good | Excellent

| Tool versions | No | No | Yes

| Error messages | Clear | Cryptic | Clear

| Installation | Single binary | Pre-installed | Requires mise

When to use Just:

Cross-project standard recipes
Simple, readable task automation
No tool version management needed

When to use mise tasks:

Project-specific with tool version pinning
Already using mise for tool management

When to use Make:

Legacy projects with existing Makefiles
Build systems requiring incremental compilation

For detailed syntax reference, advanced patterns, and troubleshooting, see REFERENCE.md.

justfile-expert

安装