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

int main()
{
  int fd;

  fd = open("f1.txt", O_WRONLY | O_CREAT | O_TRUNC, 0666);
  dup2(fd, 1);
  close(fd);

  if (fork() != 0) {
    dup2(2, 1);
    sleep(3);
  } else {
    sleep(1);
    printf("This line will not be printed on the screen.");
  }
}