code: function addUser(user, options) {
    if (!runningAsRoot()) return;
    if (!user) throw new Error('You must provide an username');
    options = _.opts(options, {systemUser: false, home: null, password: null, gid: null, uid: null, groups: []});
    if (userExists(user)) {
      return;
    }
    if (isPlatform('linux')) {
      _addUserLinux(user, options);
    } else if (isPlatform('osx')) {
      _addUserOsx(user, options);
    } else if (isPlatform('windows')) {
      throw new Error("Don't know how to add user in Windows");
    } else {
      throw new Error("Don't know how to add user in current platform");
    }
  }
docs: Add a user to the system
  @function $os~addUser
  @param {string} user - Username
  @param {Object} [options]
  @param {boolean} [options.systemUser=false] - Set user as system user (UID within 100 and 999)
  @param {string} [options.home=null] - User home directory
  @param {string} [options.password=null] - User password
  @param {string|number} [options.gid=null] - User Main Group ID
  @param {string|number} [options.uid=null] - User ID
  @param {string[]} [options.groups=[]] - Extra groups for the user
  @example
  // Creates a 'mysql' user and add it to 'mysql' group
  $os.addUser('mysql', {gid: $os.getGid('mysql')});