#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>


int main(int argc, char *argv[]) {
  int fd;

  if ( argc != 2 ) {
    fprintf(stderr, "Usage: %s filename\n", argv[0]);
    return EXIT_FAILURE;
  }

  pid_t pid;
  if ((pid = fork()) == -1) {
    perror("fork");
    return EXIT_FAILURE;
  }
  
  if (pid == 0) {
    close(0);  // close existing stdin (ignore errors...)
    fd = open(argv[1], O_RDONLY);
    dup2(fd, 0);
    execl("/bin/cat", "/bin/cat");
    perror("execl"); // shouldn't get here!
    return EXIT_FAILURE;
  }

  wait(NULL);
  printf("Parent done\n");
}