command.js

var assert = require('assert');
var spawn = require('child_process').spawn;


module.exports = function Command(command, npmModule) {
  return function(argv, options, loader) {
    var options = {
      env: process.env,
      stdio: 'inherit',
      windowsVerbatimArguments: true
    };

    if (process.platform === 'win32') {
      var quotedArgs = argv.map(windowsQuoteArg).join('');
      var file = 'cmd.exe';
      var args = ['/s', '/c', '"' + command + quotedArgs + '"'];
    } else {
      var file = '/bin/sh';
      var args = ['-c', command].concat(argv);
    }

    return spawn(file, args, options)
      .on('error', function(er) {
        loader.error('Error running %s (%s), it may need installation, try `npm update -g %s`.',
          command, er.message, npmModule);
      });
  };
};

function windowsQuoteArg(arg) {
  arg = String(arg);
  if (!/[ \t"]/.test(arg))
    return arg;

  if (!/[\\"]/.test(arg))
    return '"' + arg + '"';

  var result = '"';
  var quoteFlag = true;

  for (var i = arg.length; i >= 0; i--) {
    var char = arg[i];

    if (quoteFlag && char === '\\') {
      result = '\\' + char + result;
    } else if (char === '\\') {
      quoteFlag = true;
      result = '\\' + char + result
    } else {
      quoteFlag = false;
      result = char + result;
    }
  }

  result = ' "' + result;

  return result;
}