fork2.cpp

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>

int main()
{
  if(fork()) //1st child p2 created
  {
    printf("after first fork. pid : %d\n", getpid());
    if(fork()) //2nd child p3 created
    {
      printf("after second fork, pid: %d\n", getpid());
      fork(); //3rd child p4 created
      printf("after third fork, pid: %d\n", getpid());
    }
    printf("getting out of if, pid: %d\n", getpid());
  }
  printf("outermost, pid: %d\n", getpid());
}