Variables

Defining Variables

name = "Jake"
version = "1.0.0"
build_dir = "dist"

Using Variables

Use {{variable}} syntax in commands:

greeting = "Hello"
target = "World"

task greet:
    echo "{{greeting}}, {{target}}!"

Output: Hello, World!

Variable Scope

Variables are global and available to all recipes:

project = "myapp"

task build:
    echo "Building {{project}}"

task test:
    echo "Testing {{project}}"

Two Variable Worlds: {{var}} vs $VAR

Jake has two separate variable namespaces and they don’t override each other. This trips people up; understand it once and the rest is obvious.

Syntax	Reads from
{{name}}	Jakefile variables (name = "...") and recipe parameters
$NAME	Shell environment (loaded by @dotenv, set by @export, inherited from the parent shell)

{{...}} substitutions are resolved by Jake before the shell sees the command. $NAME substitutions are resolved by the shell at command time. Setting PORT = "3000" in the Jakefile does not put PORT in the environment, and conversely @dotenv does not put loaded values into the {{...}} namespace.

Precedence within each namespace

For {{name}}:

1. Recipe parameters passed at the command line (jake build env=prod → {{env}} is prod for that run)
2. Jakefile variables (name = "..." assignments)

For $NAME:

1. Variables set on the same shell command line (PORT=9999 jake serve)
2. @export VAR=value directives
3. .env values loaded by @dotenv
4. Variables inherited from the shell that started Jake

Worked example

@dotenv

PORT = "3000"

task serve:
    echo "via Jake namespace: {{PORT}}"   # always prints "3000"
    echo "via shell env:      $PORT"      # prints whatever the env says

With .env containing PORT=8080:

$ jake serve
via Jake namespace: 3000
via shell env:      8080

If you want a single value to drive both, set it once and pick the right syntax on the consuming side. To pass a Jakefile variable to a subprocess as an environment variable, set it inline on the command — Jake expands the {{...}} before the shell sees it:

APP_PORT = "3000"

task serve:
    PORT={{APP_PORT}} my-server

@export VAR=value passes value through to subprocesses verbatim — {{...}} inside an @export value is not expanded.

Environment Variables

Loading .env Files

@dotenv                    # Load .env
@dotenv ".env.local"       # Load specific file

Files are loaded in order; later files override earlier ones.

Exporting Variables

@export NODE_ENV=production
@export DEBUG=false

Exported variables are passed to all subprocess commands.

Using in Commands

Use $VAR or ${VAR} syntax:

task show:
    echo "Node: $NODE_ENV"
    echo "Debug: ${DEBUG}"

.env File Format

# Database settings
DATABASE_URL=postgres://localhost/myapp
DB_POOL_SIZE=10

# API Keys (use quotes for special chars)
API_KEY="abc123!@#"

# Empty values
EMPTY_VAR=

# Escape sequences
MULTILINE=line1\nline2
WINDOWS_PATH=C:\\Users\\Name

Supported escapes: \n, \t, \r, \\, \", \', \$

Requiring Variables

Validate required environment variables:

@require API_KEY DATABASE_URL

task deploy:
    echo "Deploying with $API_KEY"

Jake exits with an error if any required variable is missing.