#include <cstdio>
#include <cstdlib>
#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>
#include <iostream>
using namespace std;

int main()
{
  pid_t pid;      // process id
  
  pid = fork();   // spawn child process

  if (pid < 0) { perror("fork"); exit(10); }

  if (pid == 0) { // child                                                                                       
    cout << "child process running" << endl;
    // do something here
    for (int i=0; i<100000000; ++i);
    cout << "child done" << endl;
    return 0;
  }

  // parent
  cout << "child process pid:" << pid << endl;
  waitpid(pid, 0, 0); // wait for child process to finish
  cout << "parent done" << endl;
  return 0;                            
}