#include <fstream>

#include <iostream>

#include <boost/interprocess/sync/file_lock.hpp>

#include <cstdlib>

int main()

{

  using namespace boost::interprocess;

  std::string fileName("test");

  std::fstream file;

  file.open(fileName.c_str(), std::ios::out | std::ios::binary |

      std::ios::trunc);

  if (!file.is_open() || file.bad())

  {

    std::cout << "Open failed" << std::endl;

    exit(-);

  }

  std::cout << "Process 1 open file" << std::endl;

  try {

    file_lock f_lock(fileName.c_str());

    f_lock.lock();

    std::cout << "Locked in Process 1" << std::endl;

    file.write("Process 1", );

    file.flush();

    f_lock.unlock();

    std::cout << "Unlocked from Process 1" << std::endl;

  } catch (interprocess_exception& e) {

    std::cout << e.what( ) << std::endl;

  }

  file.close();

  return ;

}

lock_guard<file_lock>  guard(lock);

{

  // ....

}