anchor.diff:        };
   
         dataDir = mkOption {
  -        default = ''/home/${cfg.user}/.config/quassel-irc.org'';
  +        default = ''/home/${user}/.config/quassel-irc.org'';
           description = ''
             The directory holding configuration files, the SQlite database and the SSL Cert.
           '';
         };
   
         user = mkOption {
  -        default = "quassel";
  +        default = null;
           description = ''
  -          The user the Quassel daemon should run as.
  +          The existing user the Quassel daemon should run as. If left empty, a default "quassel" user will be created.
           '';
         };
   
  
positive.code: 
          preStart = ''
              mkdir -p ${cfg.dataDir}
              chown ${cfg.user} ${cfg.dataDir}
          '';
  
          exec = ''
              ${pkgs.su}/bin/su -s ${pkgs.stdenv.shell} ${cfg.user} \
                  -c '${quassel}/bin/quasselcore --listen=${cfg.interface}\
                      --port=${toString cfg.portNumber} --configdir=${cfg.dataDir}'
          '';
  
negative.code: let
    quassel = pkgs.quasselDaemon;
    cfg = config.services.quassel;
    user = if cfg.user != null then cfg.user else "quassel";
  in
  
  {
  