void    raw_mode(struct termios *t)
{
  t->c_lflag &= ~ICANON;
  t->c_cc[VMIN] = 1;
  t->c_cc[VTIME] = 0;
  if (tcsetattr(0, t) == -1)
    {
      fprintf(stderr, "tcsetattr failed\n");
      exit(1);
    }
}