anchor.diff:  
           path = [ pkgs.wpa_supplicant ];
   
  -        preStart =
  -          ''
  -            touch -a ${configFile}
  -            chmod 600 ${configFile}
  -          '';
  +        preStart = ''
  +          touch -a ${configFile}
  +          chmod 600 ${configFile}
  +        '' + optionalString cfg.userControlled.enable ''
  +          if [ ! -s ${configFile} ]; then
  +            echo "ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=${cfg.userControlled.group}" >> ${configFile}
  +            echo "update_config=1" >> ${configFile}
  +          fi
  +        '';
   
           script =
             ''
  
positive.code:             '' else ''
                ifaces="${concatStringsSep " -N " (map (i: "-i${i}") ifaces)}"
              ''}
              exec wpa_supplicant -s -u -c ${configFile} $ifaces
            '';
        };
    
  
negative.code:         ${config.system.build.upstart}/sbin/restart wpa_supplicant
        '';
  
      assertions = [{ assertion = !cfg.userControlled.enable || cfg.interfaces != []; 
                      message = "user controlled wpa_supplicant needs explicit networking.wireless.interfaces";}];
  
  
    };
  
  }
  