Lieutenant Commander

The complete solution for node.js command-line interfaces, a fork of commander.

Installation

$ npm install ltcdr --save

Commands & Actions

#!/usr/bin/env node

program
  .command('initialize [env]')
  .alias('init')
  .alias('i')
  .description('initializes a deploy config for the given environment')
  .option('-b, --branch [name]', 'Which branch to use')
  .action(function(env, options) {
    var branch = options.branch || 'master';
    env = env || 'prod';
    console.log('initialized %s environment for %s branch', env, branch);
  })
  .parse(process.argv);

// deployer initialize alpha
// deployer init beta
// deployer i prod

Commands can also have aliases, so the following is equivalent:

program
  .command('generate')
  .aliases(['gen', 'g'])
  .description('generate a new config')
  .action(generate);

// is equivalent to

program
  .command('generate')
  .description('generate a new config')
  .action(generate);

program
  .command('gen')
  .description('generate a new config')
  .action(generate);

program
  .command('g')
  .description('generate a new config')
  .action(generate);

Aliases are optional, and can take a string or an array, e.g. alias('s') or aliases(['s', 'sup']).

Option parsing

Options with lieutenant commander are defined with the .option() method, also serving as documentation for the options. The example below parses args and options from process.argv, leaving remaining args as the program.args array which were not consumed by options.

#!/usr/bin/env node

var program = require('ltcdr');

program
  .version('0.0.1')
  .option('-p, --peppers', 'Add peppers')
  .option('-P, --pineapple', 'Add pineapple')
  .option('-b, --bbq', 'Add bbq sauce')
  .option('-c, --cheese [type]', 'Add the specified type of cheese [marble]', 'marble')
  .parse(process.argv);

console.log('you ordered a pizza with:');
if (program.peppers) console.log('  - peppers');
if (program.pineapple) console.log('  - pineapple');
if (program.bbq) console.log('  - bbq');
console.log('  - %s cheese', program.cheese);

Short flags may be passed as a single arg, for example -abc is equivalent to -a -b -c. Multi-word options such as "--template-engine" are camel-cased, becoming program.templateEngine etc.

Automated --help

The help information is auto-generated based on the information lieutenant commander already knows about your program, so the following --help info is for free:

 $ ./examples/pizza --help

   Usage: pizza [options]

   Options:

     -V, --version        output the version number
     -p, --peppers        Add peppers
     -P, --pineapple      Add pineapple
     -b, --bbq            Add bbq sauce
     -c, --cheese <type>  Add the specified type of cheese [marble]
     -h, --help           output usage information

Coercion

function range(val) {
  return val.split('..').map(Number);
}

function list(val) {
  return val.split(',');
}

program
  .version('0.0.1')
  .usage('[options] <file ...>')
  .option('-i, --integer <n>', 'An integer argument', parseInt)
  .option('-f, --float <n>', 'A float argument', parseFloat)
  .option('-r, --range <a>..<b>', 'A range', range)
  .option('-l, --list <items>', 'A list', list)
  .option('-o, --optional [value]', 'An optional value')
  .parse(process.argv);

console.log(' int: %j', program.integer);
console.log(' float: %j', program.float);
console.log(' optional: %j', program.optional);
program.range = program.range || [];
console.log(' range: %j..%j', program.range[0], program.range[1]);
console.log(' list: %j', program.list);
console.log(' args: %j', program.args);

Custom help

You can display arbitrary -h, --help information by listening for "--help". Commander will automatically exit once you are done so that the remainder of your program does not execute causing undesired behaviours, for example in the following executable "stuff" will not output when --help is used.

#!/usr/bin/env node

/**
 * Module dependencies.
 */

var program = require('../');

function list(val) {
  return val.split(',').map(Number);
}

program
  .version('0.0.1')
  .option('-f, --foo', 'enable some foo')
  .option('-b, --bar', 'enable some bar')
  .option('-B, --baz', 'enable some baz');

// must be before .parse() since
// node's emit() is immediate

program.on('--help', function(){
  console.log('  Examples:');
  console.log('');
  console.log('    $ custom-help --help');
  console.log('    $ custom-help -h');
  console.log('');
});

program.parse(process.argv);

console.log('stuff');

yielding the following help output:


Usage: custom-help [options]

Options:

  -h, --help     output usage information
  -V, --version  output the version number
  -f, --foo      enable some foo
  -b, --bar      enable some bar
  -B, --baz      enable some baz

Examples:

  $ custom-help --help
  $ custom-help -h