k 3 fetchWallpaper: scrap predicate, use unitConfig

2configs/fetchWallpaper.nix

@@ -1,24 +1,15 @@
 { config, pkgs, ... }:
 
-let
-  # check if laptop runs on umts
-  weaksauce-internet = with pkgs;writeScript "weaksauce-internet" ''
-    #! /bin/sh
-    if  ${iproute}/bin/ip addr show dev ppp0 2>/dev/null \
-      | ${gnugrep}/bin/grep -q inet;then
-      exit 1
-    fi
-  '';
-
-in {
+{
   krebs.fetchWallpaper = {
     enable = true;
     display = ":0";
-    predicate = weaksauce-internet;
+    unitConfig.ConditionPathExists = "!/var/run/ppp0.pid";
     timerConfig = {
       OnCalendar = "*:0/30";
     };
     url = "http://echelon/wallpaper.png";
   };
+
 }