cac

What is cac?

The cac npm package is a simple yet powerful framework for building command-line applications. It allows developers to parse arguments, generate help messages, and create commands with options and sub-commands.

What are cac's main functionalities?

Command Parsing

This feature allows you to define commands with required and optional arguments. The code sample demonstrates how to create a command 'init' that requires a project name and accepts an optional type argument.

{"const cac = require('cac');\nconst cli = cac();\ncli.command('init <name>', 'Initialize a project')\n  .option('--type <type>', 'Project type')\n  .action((name, options) => {\n    console.log(`Initializing project: ${name} with type: ${options.type}`);\n  });\ncli.help();\ncli.parse();"}

Help Generation

Automatically generates help information for the defined commands and options. The code sample shows how to define a 'build' command and an option to minify the output, with automatic help generation.

{"const cac = require('cac');\nconst cli = cac();\ncli.command('build', 'Build the project')\n  .option('--minify', 'Minify the output')\ncli.help();\ncli.parse();"}

Sub-commands

Supports the creation of sub-commands for more complex CLI structures. The code sample illustrates how to create a 'deploy' command with sub-commands for different deployment providers like AWS and Azure.

{"const cac = require('cac');\nconst cli = cac();\nconst deploy = cli.command('deploy <provider>', 'Deploy your project');\ndeploy.command('aws', 'Deploy to AWS')\n  .action(() => {\n    console.log('Deploying to AWS...');\n  });\ndeploy.command('azure', 'Deploy to Azure')\n  .action(() => {\n    console.log('Deploying to Azure...');\n  });\ncli.help();\ncli.parse();"}

Other packages similar to cac

commander

Commander is one of the most popular npm packages for building command-line interfaces. It offers similar functionalities to cac, such as command parsing, option management, and automatic help generation. Commander has a more extensive feature set and a larger community, but cac is known for its simplicity and ease of use.

yargs

Yargs is another well-known package for building command-line tools. It provides a rich API for argument parsing, command chaining, and validation. Yargs is more verbose and configurable compared to cac, which might be preferred for more complex CLI applications.

meow

Meow is a lightweight CLI helper with a minimalistic approach. It is less feature-rich than cac but is very straightforward to use for simple command-line applications. Meow is a good choice for those who need something simpler than cac and do not require complex command structures.

README

cac

Command And Conquer, the queen living in your command line.

Install

$ npm install --save cac

Usage

const cac = require('cac')

// initialize your cli program
const cli = cac()

// add your very first command
cli.command('hi', 'Say hi!', (input) => {
  console.log(`hi ${input[1] || 'boy'}!`)
})

// parse arguments and bootstrap
cli.parse()

Default commands and options

• Options: --help -h --version -v
• Commands: help

API

.option(options, description, defaultValue)

• options: string, it could be option or option, alias or alias, option, the order does not matter. eg: .option('install, i')
• description: string, option description, will be used to output cli usage
• defaultValue: any, give a default value to this option

.command(commands, description, fn)

• commands: string, it could be command or command, alias or alias, command, the order does not matter. eg: .command('clone, c'). It can also be a wildcard symbol *, which means always been triggered if no command was specified by user.
• description: string, command description, will be used to output cli usage
• fn: function, command function, will be triggered when this command matches user's input, the function takes two arguments:
  • input: non-flag arguments
  • flags: flags converted to camelCase

.usage(text)

• text: string, the cli usage. default is $bin [options] [commands]

.parse(argv)

• argv: array, default is process.argv.slice(2)

.onError(handleError)

• handleError: function, triggered when your program throws an error or was rejected by a Promise call.

.string(string | array)

a string or array of strings argument names to always treat as strings

.boolean(boolean | string | array)

a boolean, string or array of strings to always treat as booleans. if true will treat all double hyphenated arguments without equal signs as boolean (e.g. affects --foo, not -f or --foo=bar)

License

MIT © egoist