anchor.diff:          '';
           description = "Additional configurations to be appended to <filename>bitcoin.conf</filename>.";
         };
  +
         dataDir = mkOption {
           type = types.path;
  -        default = "/var/lib/bitcoind";
  +        default = "/var/lib/bitcoind-${name}";
           description = "The data directory for bitcoind.";
         };
   
         user = mkOption {
           type = types.str;
  -        default = "bitcoin";
  +        default = "bitcoind-${name}";
           description = "The user as which to run bitcoind.";
         };
  +
         group = mkOption {
           type = types.str;
  -        default = cfg.user;
  +        default = config.user;
           description = "The group as which to run bitcoind.";
         };
   
  
positive.code:         description = ''
            Password HMAC-SHA-256 for JSON-RPC connections. Must be a string of the
            format &lt;SALT-HEX&gt;$&lt;HMAC-HEX&gt;.
          '';
        };
      };
  
negative.code:               bob.passwordHMAC = "b2dd077cb54591a2f3139e69a897ac$4e71f08d48b4347cf8eff3815c0e25ae2e9a4340474079f55705f40574f4ec99";
              }
            '';
            type = with types; attrsOf (submodule rpcUserOpts);
            description = ''
              RPC user information for JSON-RPC connnections.
            '';
          };
        };
  
        pidFile = mkOption {
          type = types.path;
          default = "${config.dataDir}/bitcoind.pid";
          description = "Location of bitcoind pid file.";
        };
  
        testnet = mkOption {
          type = types.bool;
          default = false;
          description = "Whether to use the testnet instead of mainnet.";
        };
  
        port = mkOption {
          type = types.nullOr types.port;
          default = null;
          description = "Override the default port on which to listen for connections.";
        };
  
        dbCache = mkOption {
          type = types.nullOr (types.ints.between 4 16384);
          default = null;
          example = 4000;
          description = "Override the default database cache size in MiB.";
        };
  
        prune = mkOption {
          type = types.nullOr (types.coercedTo
            (types.enum [ "disable" "manual" ])
  