use warnings;
use strict;
use Getopt::Long;

my $do_first = 0;
sub first { $do_first = 1 }

my $do_second = 0;
sub second { $do_second = 1 }

GetOptions(first=>\&first, second=>\&second)
	or die "Invalid options passed to $0\n";

if ($do_first) { print "First!\n" }

if ($do_second) { print "Second!\n" }

__END__

$ perl 11140961.pl --first --second --first --second --second --first
First!
Second!
$ perl 11140961.pl --first --second --year --first --second --second --first
Unknown option: year
Invalid options passed to 11140961.pl