Migrating from Just

If you’re coming from Just, the transition to Jake is smooth. Most syntax is similar or identical.

Syntax Comparison

Just	Jake
`recipe:`	`task recipe:` (or simple syntax)
`{{var}}`	`{{var}}` (same!)
`set dotenv-load`	`@dotenv`
`@recipe` (quiet)	`@quiet` decorator
`[group: 'x']`	`@group x`
`[confirm]`	`@confirm "message"`
`[private]`	`@hidden` or prefix with `_`

Key Differences

Recipe Keyword

Just uses bare recipe names. Jake prefers the task keyword for clarity, but also supports simple syntax:

# Jake with task keyword (recommended)
task build:
    cargo build

# Jake with simple syntax (Just-like)
build:
    cargo build

.env Loading

Just uses a global setting. Jake uses a directive:

# Just: set dotenv-load
# Jake:
@dotenv
@dotenv ".env.local"  # Can load multiple files

Groups

Just uses attributes. Jake uses a directive:

# Just: [group: 'build']
# Jake:
@group build
task compile:
    cargo build

Confirmations

Just uses an attribute. Jake uses a directive with a message:

# Just: [confirm]
# Jake:
task deploy:
    @confirm "Deploy to production?"
    ./deploy.sh

Private Recipes

Just uses an attribute. Jake supports both @hidden directive and underscore prefix:

# Just: [private]
# Jake option 1: @hidden directive
@hidden
task helper:
    echo "I'm hidden from --list"

# Jake option 2: underscore prefix
task _other-helper:
    echo "Also hidden from --list"

task public: [helper, _other-helper]
    echo "I use the hidden helpers"

Example Migration

Before (justfile)

set dotenv-load

default:
    @just --list

build:
    cargo build

test: build
    cargo test

[confirm("Deploy to production?")]
[group: 'deploy']
deploy: test
    ./deploy.sh

After (Jakefile)

@dotenv

@default
task list:
    jake --list

task build:
    cargo build

task test: [build]
    cargo test

@group deploy
task deploy: [test]
    @confirm "Deploy to production?"
    ./deploy.sh

What Jake Adds

Migrating from Just gives you new capabilities:

1. File-Based Dependencies

Track source files and only rebuild when changed:

file dist/bundle.js: src/**/*.ts
    esbuild src/index.ts --bundle --outfile=dist/bundle.js

This skips the build if no TypeScript files changed since the last run.

2. Glob Patterns

Reference files with wildcards:

file dist/app.js: src/**/*.ts
    tsc --outFile dist/app.js

3. Parallel Execution

Run independent tasks simultaneously:

jake -j4 all    # 4 parallel workers
jake -j all     # Use CPU count

4. Pre/Post Hooks

Run setup and cleanup around recipes:

task deploy:
    @pre echo "Starting deployment..."
    ./deploy.sh
    @post echo "Deployment complete!"

5. Watch Mode

Re-run tasks when files change:

jake -w build
jake -w "src/**/*.ts" build

6. @needs Directive

Verify tools exist before running:

task build:
    @needs node npm esbuild
    npm run build

7. Error Hooks

Handle failures globally:

@on_error notify "Build failed!"

task build:
    npm run build

Migration Tips

Add task keyword - For clarity (or keep simple syntax)
Convert attributes - Replace [...] with @... directives
Move dotenv - Change set dotenv-load to @dotenv
Use file recipes - Replace always-run tasks with file when appropriate
Add parallelism - Use -j for faster builds

Keeping Compatibility

If you want to gradually migrate, you can:

Keep your justfile during transition
Run specific tasks with both tools to verify behavior
Once confident, remove the justfile