Pgidchange.c

#include <stdio.h>
#include <unistd.h>
int	main()
{
  gid_t	gid;
  int childPID;

  printf("Start PID : %d\n", getpid());
  printf("Start GPID : %d\n", getpgrp());
  gid = 0;
  if ((childPID = fork()) == -1)
    perror("fork failed");
  if (childPID == 0)
  {
    setsid();
    printf("Child GPID : %d\n", getpgrp());
    while (1)
    {
      printf("Child still here...\n");
      sleep(1);
    }
  }
  else
  {
    printf("Parent GPID : %d\n", getpgrp());
    while (1)
    {
      printf("Parent still here...\n");
      sleep(1);
    }
  }
}