Now I am confused a bit. The $! in the following, when it died, did not tell me that I was using ioctl inappropriately. The reason I am confused is that the lines of code in my OP were inside-out conditionals (don't remember where I got that term), but the code below is just a conditional too.

sub four_digit_year {
 my $year = shift;

  if ($year !~ /\d{4}/) {
    die "Sorry, please use the four digit year. Stopped $!";
  }

  return $year;
}
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