boost file lock code

bool interrupted(false);

void
signal_callback(int signum)
{
  cout << "Caught signal: " << signum << endl;

  interrupted = true;
}

int
main(int argc,
     char * argv[])
{
  ::signal(SIGINT, signal_callback);

  string filename("foo");
  int pid(getpid());

  file_lock _file_lock(filename.c_str());
  scoped_lock<file_lock> _scoped_lock(_file_lock, try_to_lock);

  cout << "Process with PID: " << pid
       << " has lock on file: " << filename   << endl;

  while(true)
    {
      //do work
      //...

      if(interrupted)
        {
          cout << "Exiting now" << endl;
          break;
        }

      cout << pid << " still holding on to lock on foo" << endl;

      ::sleep(5);
    }
}