code: function enable(options, callback) {
    var file = options.interface + '-udhcpd.conf';
  
    var commands = [].concat(
      'cat <<EOF >' + file + ' && udhcpd ' + file + ' && rm -f ' + file,
      expand(options));
  
    return this.exec(commands.join('\n'), callback);
  }
docs: The **udhcpd enable** command is used to start a dhcp server on a
  specific network interface.
  
  @static
  @category udhcpd
  @param {object} options The dhcp server configuration.
  @param {function} callback The callback function.
  @returns {process} The child process.
  @example
  
  var udhcpd = require('wireless-tools/udhcpd');
  
  var options = {
  interface: 'wlan0',
  start: '192.168.10.100',
  end: '192.168.10.200',
  option: {
  router: '192.168.10.1',
  subnet: '255.255.255.0',
  dns: [ '4.4.4.4', '8.8.8.8' ]
  }
  };
  
  udhcpd.enable(options, function(err) {
  // the dhcp server was started
  });