write 10 bytes of each password and user_id to pipe

for (int i=0; i<MAXPASSWORD; i++){
      if (write(fd[1], user_id+i, 1) == -1){
        perror("write");
        exit(1);
      }
    }
    for (int i=0; i<MAXPASSWORD; i++){
      if (write(fd[1], password+i, 1) == -1){
        perror("write");
        exit(1);
      }
    }