code: function manual(options, callback) {
    var command = [
      'wpa_supplicant',
      '-i', options.interface,
      '-s -B -P /run/wpa_supplicant/' + options.interface + '.pid',
      '-D', options.drivers.join(','),
      '-C /run/wpa_supplicant'
    ].join(' ');
  
    return this.exec(command, callback);
  }
docs: launchs wpa manually (as if it were launched by ifup if interface wpa setup
  was done in /network/interfaces)
  /sbin/wpa_supplicant -s -B -P /run/wpa_supplicant.wlan0.pid -i wlan0 -D nl80211,wext -C /run/wpa_supplicant
  options = {
  interface: 'wlan0',
  drivers: [ 'nl80211', 'wext' ]
  }