Conditionals

Basic If/Else

task install:
    @if env(CI)
        npm ci
    @else
        npm install
    @end

If/Elif/Else

task deploy:
    @if env(PRODUCTION)
        echo "Deploying to production"
    @elif env(STAGING)
        echo "Deploying to staging"
    @else
        echo "Deploying to development"
    @end

Condition Functions

Function	Description
`env(VAR)`	True if environment variable is set and non-empty
`exists(path)`	True if file or directory exists
`command(name)`	True if command exists in PATH
`eq(a, b)`	True if strings are equal
`neq(a, b)`	True if strings are not equal
`is_watching()`	True if running in watch mode (`-w`)
`is_dry_run()`	True if running in dry-run mode (`-n`)
`is_verbose()`	True if running in verbose mode (`-v`)
`is_macos()`	True if running on macOS
`is_linux()`	True if running on Linux
`is_windows()`	True if running on Windows
`is_unix()`	True if running on Unix-like OS (Linux, macOS, BSD)
`is_platform(name)`	True if running on the specified platform

Runtime State Conditions

Check how jake was invoked:

task build:
    @if is_watching()
        echo "Watch mode: skipping expensive lint"
    @else
        npm run lint
    @end
    npm run build

task deploy:
    @if is_dry_run()
        echo "[DRY RUN] Would deploy to production"
    @else
        rsync dist/ server:/var/www/
    @end

task test:
    @if is_verbose()
        npm test -- --verbose
    @else
        npm test
    @end

File Existence

task setup:
    @if exists(node_modules)
        echo "Dependencies already installed"
    @else
        npm install
    @end

String Comparison

task build:
    @if eq($BUILD_MODE, "release")
        cargo build --release
    @else
        cargo build
    @end

Command Availability

Check if tools are available before using them:

task build:
    @if command(docker)
        docker build -t myapp .
    @elif command(podman)
        podman build -t myapp .
    @else
        echo "No container runtime found"
    @end

task deploy:
    @if command(kubectl)
        kubectl apply -f k8s/
    @else
        echo "kubectl not installed - skipping deploy"
    @end

Works with absolute paths too:

task check:
    @if command(/usr/local/bin/custom-tool)
        /usr/local/bin/custom-tool run
    @end

Platform Detection

Run platform-specific commands:

task install:
    @if is_macos()
        brew install ripgrep
    @elif is_linux()
        apt-get install ripgrep
    @elif is_windows()
        choco install ripgrep
    @end

task open:
    @if is_macos()
        open https://jakefile.dev
    @elif is_linux()
        xdg-open https://jakefile.dev
    @elif is_windows()
        start https://jakefile.dev
    @end

Use is_unix() for commands that work on all Unix-like systems:

task permissions:
    @if is_unix()
        chmod +x ./script.sh
    @end

Use is_platform() for flexible platform matching:

task build:
    @if is_platform(freebsd)
        gmake build
    @else
        make build
    @end