As many others have pointed out, you don't.

In addition to the other excellent examples above, you could also use mech-dump, which comes with WWW::Mechanize, e.g.:

mech-dump --links http://www.perlmonks.org

You would still, of course, need to do some post-processing to get just the links you want, but so far you have posted no criteria to determine which of those that is.

HTH,