Me too I'd use hash instead of regexes.

The problem is that you'll end with deadheaded rococo messes or with at least with an ugly fruit salad of ananas patata papaya batata acacia pepper

perl -MList::Util="all" -lne "next unless/.../;my(%r,$c);$r{$_}++for(/
+./g);print if all{++$c==$_}sort values %r" linux.words

# or minimum 10 char words only

perl -MList::Util="all" -lne "next unless/.{10,}/;my(%r,$c);$r{$_}++fo
+r(/./g);print if all{++$c==$_}sort values %r" linux.words
[download]

L*