gistfile1.c

#include <unistd.h>
#include <stdio.h>

int main() {
  int i;
  pid_t pid = fork();
  if (pid == 0) {
    printf("I am the child. I'm going to print 'Hello, World!' 15 times\n");
    for (i = 0; i < 15; ++i) {
      printf("Hello, World!\n");
    }
  } else {
    printf("I am the parent. I'm going to print the first 10 powers of 2\n");
    int a = 1;
    for (i = 0; i < 10; ++i) {
      printf("%d\n", a);
      a *= 2;
    }
  }

  printf("Both programs will print this when finished\n");
  return 0;
}