how do you test for "no command line options specified" if each key in %option equals 1 by default?

They only equal 1 if the option is specified. For those options that take a value, you either get 1 or the value specified on the command line.

Another related question: I'm trying to say "if you use this option, it needs to accompany another option",

unless ($option{f} && $option{h}) {
   die "If you use -f, you must also use -h, and vice versa.";
}
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Assuming I understand you correctly. Or if you wanted the relation to be one-way (i.e., -f needs to accompany -h, but -h doesn't need to accompany -f) then you could do something like this:

if ($option{f} && !$option{h}) {
   die "If you use -f, you must also use -h";
}
if ($option{h}) { ... }
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