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

int main(void) {
   pid_t childpid;

   childpid = fork();
   if (childpid == -1) {
      perror("Failed to fork");
      return 1;
   }
   if (childpid == 0)                             /* child code */
      printf("I am child %ld\n", (long)getpid());
   else                                          /* parent code */
      printf("I am parent %ld\n", (long)getpid());
   return 0;
}