You needn't repetitively scan if you store a map inside a hash structure.:

#like this...

#Set up the link-map;
my %linkmap;
my @pages = glob(*.cfm);
foreach $page (@pages) {
   @links_to = find_links($page); #your sub
   for (@links_to) {
      $linkmap{$page}{$_} = undef;
   }
}

#print out what links to each file
foreach $page (@pages) {
   print "What links to $page: ".join(';',what_links_to($page));
}

# sub to find what links to something
sub what_links_to {
   my $dest = shift; #i.e. 'a.cfm' for what links to 'a.cfm'
   my @links_to;
   for (keys %linkmap) {
      next if ($_ eq 'a.cfm'); #skip what 'a.cfm' links to
      push (@links_to, $_) if exists $linkmap{$_}{'a.cfm'};
   }
   return @links_to;
}
[download]

So you only scan the files once, and then check the hash repeatedly. Much faster.

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