#include <unistd.h>

int main(int argc, char **argv)
{
  int pipefd[2];
  pipe(pipefd);
  if (fork())
    {
      dup2(pipefd[0], 0);
      close(pipefd[0]);
      close(pipefd[1]);
      execlp("grep", "grep", "int", NULL);
    }
  else
    {
      dup2(pipefd[1], 1);
      close(pipefd[0]);
      close(pipefd[1]);
      execlp("cat", "cat", argv[1], NULL);
    }
  return -1;
}