Options & Arguments

Options (flags) and arguments are how users provide input to your commands.

Options

Options are named parameters passed with --option or -o syntax.

Basic Options

cli.addCommand({
    name: "build",
    options: [
        {
            name: "production",
            type: Boolean,
            description: "Build for production",
        },
    ],
    execute: ({ options }) => {
        console.log(options.production); // true or false
    },
});

Usage:

cli build --production  # options.production = true
cli build              # options.production = false

Option Types

Boolean Options

{
  name: "verbose",
  type: Boolean,
  description: "Enable verbose output"
}

String Options

{
  name: "output",
  type: String,
  description: "Output directory"
}

Usage: cli build --output dist

Number Options

{
  name: "port",
  type: Number,
  description: "Server port"
}

Usage: cli serve --port 3000

Array Options

Options can accept multiple values:

{
  name: "files",
  type: String, // Will be an array
  multiple: true,
  description: "Files to process"
}

Usage: cli process --files file1.txt --files file2.txt

Aliases

Provide short aliases for options:

{
  name: "output",
  alias: "o",
  type: String,
  description: "Output directory"
}

Usage:

cli build --output dist
cli build -o dist  # Same as above

Default Values

Set default values for options:

{
  name: "port",
  type: Number,
  defaultValue: 3000,
  description: "Server port"
}

execute: ({ options }) => {
    console.log(options.port); // 3000 if not provided
};

Required Options

Make options mandatory:

{
  name: "config",
  type: String,
  required: true,
  description: "Configuration file path"
}

If not provided, Cerebro will throw an error with a helpful message.

Negatable Options

Boolean options can be negated with --no- prefix:

{
  name: "color",
  type: Boolean,
  defaultValue: true,
  description: "Enable colored output"
}

Usage:

cli build --color        # options.color = true
cli build --no-color     # options.color = false
cli build                # options.color = true (default)

Conflicting Options

Prevent certain options from being used together:

cli.addCommand({
    name: "serve",
    options: [
        {
            name: "http",
            type: Boolean,
            conflicts: "https",
            description: "Use HTTP",
        },
        {
            name: "https",
            type: Boolean,
            conflicts: "http",
            description: "Use HTTPS",
        },
    ],
    execute: () => {},
});

Using both will throw an error:

cli serve --http --https  # Error: Options "http" and "https" cannot be used together

Implied Options

Automatically set other options when one is used:

cli.addCommand({
    name: "build",
    options: [
        {
            name: "production",
            type: Boolean,
            implies: { minify: true, sourcemap: false },
            description: "Build for production",
        },
        {
            name: "minify",
            type: Boolean,
            description: "Minify output",
        },
        {
            name: "sourcemap",
            type: Boolean,
            description: "Generate source maps",
        },
    ],
    execute: ({ options }) => {
        // If --production is used, minify=true and sourcemap=false automatically
    },
});

Boolean Options

Boolean options are simple flags that are either present (true) or absent (false):

{
  name: "watch",
  type: Boolean,
  description: "Watch for changes"
}

Usage:

cli build --watch  # options.watch = true
cli build          # options.watch = false

Note: If you need an option that can accept values, use a String type instead:

{
  name: "watch",
  type: String,
  description: "Watch mode (e.g., 'port' or 'file')"
}

Hidden Options

Hide options from help output:

{
  name: "debug",
  type: Boolean,
  hidden: true, // Won't appear in help
  description: "Enable debug mode"
}

Type Labels

Customize the type label shown in help:

{
  name: "port",
  type: Number,
  typeLabel: "<port>", // Instead of <number>
  description: "Server port"
}

Positional Arguments

Positional arguments are provided without option names:

cli.addCommand({
    name: "copy",
    argument: {
        name: "source",
        type: String,
        description: "Source file",
    },
    execute: ({ argument }) => {
        const source = argument[0];
        console.log(`Copying ${source}...`);
    },
});

Usage: cli copy file.txt

Multiple Arguments

Arguments accept multiple values:

cli.addCommand({
    name: "copy",
    argument: {
        name: "files",
        type: String,
        description: "Files to copy",
    },
    execute: ({ argument }) => {
        // argument is an array
        argument.forEach((file) => {
            console.log(`Copying ${file}...`);
        });
    },
});

Usage: cli copy file1.txt file2.txt file3.txt

Argument Default Values

argument: {
  name: "name",
  type: String,
  defaultValue: "World",
  description: "Name to greet"
}

Argument Types

Arguments support the same types as options:

String - Text values
Number - Numeric values
Boolean - Boolean values (rare for arguments)

Accessing Options and Arguments

In your command's execute function:

execute: ({ options, argument }) => {
    // Options
    const isProduction = options.production;
    const outputDir = options.output || "dist";

    // Arguments
    const fileName = argument[0];
    const allFiles = argument; // Array of all arguments
};

Complete Example

cli.addCommand({
    name: "deploy",
    argument: {
        name: "target",
        type: String,
        defaultValue: "production",
        description: "Deployment target",
    },
    options: [
        {
            name: "env",
            alias: "e",
            type: String,
            required: true,
            description: "Environment name",
        },
        {
            name: "force",
            alias: "f",
            type: Boolean,
            defaultValue: false,
            description: "Force deployment",
        },
        {
            name: "dry-run",
            type: Boolean,
            description: "Perform a dry run",
        },
        {
            name: "services",
            type: String,
            multiple: true,
            description: "Services to deploy",
        },
    ],
    execute: ({ argument, options }) => {
        const target = argument[0];
        const env = options.env;
        const force = options.force;
        const services = options.services || [];

        console.log(`Deploying to ${target} (${env})`);
        if (force) {
            console.log("Force mode enabled");
        }
        if (services.length > 0) {
            console.log(`Services: ${services.join(", ")}`);
        }
    },
});

Usage examples:

# Basic usage
cli deploy staging --env production

# With multiple services
cli deploy --env production --services api --services worker

# Force deployment
cli deploy --env production --force

# Dry run
cli deploy --env production --dry-run

Environment Variables

Environment variables provide a way to configure commands without passing values on the command line. They're useful for:

Configuration that doesn't change frequently
Sensitive values that shouldn't appear in command history
CI/CD pipelines and automation
Default settings that can be overridden by options

Defining Environment Variables

Add an env array to your command definition, similar to options:

cli.addCommand({
    name: "build",
    env: [
        {
            name: "API_KEY",
            type: String,
            description: "API key for authentication",
        },
        {
            name: "TIMEOUT",
            type: Number,
            defaultValue: 5000,
            description: "Request timeout in milliseconds",
        },
        {
            name: "VERBOSE",
            type: Boolean,
            defaultValue: false,
            description: "Enable verbose logging",
        },
    ],
    execute: ({ env }) => {
        const apiKey = env.apiKey; // camelCase: API_KEY → apiKey
        const timeout = env.timeout; // 5000 if not set
        const verbose = env.verbose; // false if not set
    },
});

Environment Variable Types

Environment variables support the same types as options:

String Environment Variables

{
    name: "API_URL",
    type: String,
    description: "API endpoint URL"
}

Usage: API_URL=https://api.example.com cli build

Number Environment Variables

{
    name: "PORT",
    type: Number,
    defaultValue: 3000,
    description: "Server port"
}

Usage: PORT=8080 cli serve

The value is parsed as an integer. Invalid values will use the default if provided.

Boolean Environment Variables

{
    name: "ENABLE_CACHE",
    type: Boolean,
    defaultValue: false,
    description: "Enable caching"
}

Boolean values are case-insensitive and accept:

true, 1, yes, on → true
false, 0, no, off, or any other value → false

Usage:

ENABLE_CACHE=true cli build
ENABLE_CACHE=1 cli build
ENABLE_CACHE=yes cli build

Default Values

Set default values that are used when the environment variable is not set:

{
    name: "LOG_LEVEL",
    type: String,
    defaultValue: "info",
    description: "Logging level"
}

execute: ({ env }) => {
    // env.logLevel will be "info" if LOG_LEVEL is not set
    console.log(env.logLevel);
};

Hidden Environment Variables

Hide environment variables from help output:

{
    name: "SECRET_KEY",
    type: String,
    hidden: true, // Won't appear in help
    description: "Secret key for encryption"
}

CamelCase Conversion

Environment variable names are automatically converted to camelCase:

API_KEY → env.apiKey
LOG_LEVEL → env.logLevel
ENABLE_SSL → env.enableSsl

Accessing Environment Variables

Access environment variables through the env property in your command's execute function:

cli.addCommand({
    name: "deploy",
    env: [
        {
            name: "DEPLOY_ENV",
            type: String,
            defaultValue: "staging",
            description: "Deployment environment",
        },
        {
            name: "FORCE_DEPLOY",
            type: Boolean,
            defaultValue: false,
            description: "Force deployment without confirmation",
        },
    ],
    execute: ({ env, options }) => {
        const deployEnv = env.deployEnv; // "staging" if not set
        const forceDeploy = env.forceDeploy; // false if not set

        // Can combine with options
        const finalEnv = options.env || env.deployEnv;
    },
});

Complete Example

cli.addCommand({
    name: "build",
    env: [
        {
            name: "NODE_ENV",
            type: String,
            defaultValue: "development",
            description: "Node.js environment",
        },
        {
            name: "BUILD_TIMEOUT",
            type: Number,
            defaultValue: 30000,
            description: "Build timeout in milliseconds",
        },
        {
            name: "ENABLE_SOURCEMAPS",
            type: Boolean,
            defaultValue: true,
            description: "Generate source maps",
        },
    ],
    options: [
        {
            name: "output",
            type: String,
            description: "Output directory",
        },
    ],
    execute: ({ env, options }) => {
        const nodeEnv = env.nodeEnv; // "development" or value from NODE_ENV
        const timeout = env.buildTimeout; // 30000 or value from BUILD_TIMEOUT
        const sourcemaps = env.enableSourcemaps; // true or value from ENABLE_SOURCEMAPS
        const output = options.output || "dist";

        console.log(`Building for ${nodeEnv} with timeout ${timeout}ms`);
        if (sourcemaps) {
            console.log("Source maps enabled");
        }
    },
});

Usage examples:

# Using defaults
cli build

# Override with environment variables
NODE_ENV=production BUILD_TIMEOUT=60000 cli build

# Combine with options
ENABLE_SOURCEMAPS=false cli build --output build

# Boolean values
ENABLE_SOURCEMAPS=1 cli build  # true
ENABLE_SOURCEMAPS=0 cli build  # false

Environment Variables in Help

Environment variables are automatically displayed in the help output:

cli help build

Output includes an "Environment Variables" section showing:

Variable name
Description
Default value (if set)

Hidden environment variables are excluded from help output.

Global Options

Cerebro provides built-in global options available to all commands:

--help, -h - Show help
--version, -V - Show version
--verbose, -v - Verbose output
--debug - Debug output
--quiet, -q - Quiet output
--no-color - Disable colored output
--color - Force colored output

These don't need to be defined in your commands.

Global Environment Variables

Cerebro also provides built-in global environment variables:

CEREBRO_OUTPUT_LEVEL - Controls verbosity level (16=quiet, 32=normal, 64=verbose, 128=debug)
CEREBRO_MIN_NODE_VERSION - Overrides minimum Node.js version check
NO_UPDATE_NOTIFIER - Disables update notifier check
NODE_ENV - Standard Node.js environment variable
DEBUG - Enables debug output (same as --debug flag)

These are available to all commands and appear in the general help output.

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