anchor.diff:                fi
               fi
             done
  +          if [ -z "$args" ]; then
  +            echo >&2 "<3>No wireless interfaces detected (yet)."
  +            exit 1
  +          fi
           '' else ''
             args="${concatMapStringsSep " -N " (i: "-i${i} $iface_args") ifaces}"
           ''}
  
positive.code:       path = [ pkgs.wpa_supplicant ];
  
        script = ''
          if [ -f /etc/wpa_supplicant.conf -a "/etc/wpa_supplicant.conf" != "${configFile}" ]
          then echo >&2 "<3>/etc/wpa_supplicant.conf present but ignored. Generated ${configFile} is used instead."
          fi
          iface_args="-s -u -D${cfg.driver} -c ${configFile}"
          ${if ifaces == [] then ''
            for i in $(cd /sys/class/net && echo *); do
  
negative.code: 
      # Restart wpa_supplicant when a wlan device appears or disappears.
      services.udev.extraRules = ''
        ACTION=="add|remove", SUBSYSTEM=="net", ENV{DEVTYPE}=="wlan", RUN+="/run/current-system/systemd/bin/systemctl restart wpa_supplicant.service"
      '';
    };
  
  