code: public void goUpDir() throws IOException, ServerException {
          try {
              controlChannel.execute(Command.CDUP);
              // alternative: changeDir("..");
          } catch (FTPReplyParseException rpe) {
              throw ServerException.embedFTPReplyParseException(rpe);
          } catch (UnexpectedReplyCodeException urce) {
              throw ServerException.embedUnexpectedReplyCodeException(
                                  urce,
                                  "Server refused changing current directory");
          }
      }
docs: Changes remote current working directory to the higher level.