anchor.diff:  # $ nix-env -qaP | grep wget
         environment.systemPackages = with pkgs; [
           vim
  +        x11vnc
             mc
             git
             wkhtmltopdf #$ wkhtmltopdf https://nixos.org/releases/nixos/unstable/nixos-16.09pre79453.32b7b00/manual/index.html nixos_manuel.pdf
  
positive.code:   ];
  };
  
  
  security.setuidOwners = [
  { # Limit access to dumpcap to root and members of the wireshark group.
  
negative.code: ##### Misc stuff (shellInit, powerManagement etc.) #####
  nix = {
    useChroot = true;
    readOnlyStore = true; #src: https://github.com/avnik/nixos-configs/blob/master/common/nix.nix
    buildCores = 4;    # -j4 for subsequent make calls; XXX: is this same as 'build-cores' below in extraOptions?
    #maxJobs = 2;       # Parallel nix builds
    gc.automatic = true;
    gc.dates = "03:15";#src: https://nixos.org/releases/nixos/14.12/nixos-14.12.374.61adf9e/manual/sec-nix-gc.html
  
  