def pid_from_file
      if File.exist?(pid_file_path)
        pid = File.read(pid_file_path)
        pid.length > 0 ? pid.strip.to_i : nil
      else
        nil
      end
    end
def pid_from_file
      if File.exist?(pid_file_path)
        pid = File.read(pid_file_path)
        pid.length > 0 ? pid.strip.to_i : nil
      else
        nil
      end
    end
Return the PID that is in the instances process PID file