You can avoid regex's altogether

#!/usr/bin/perl

use strict;
use warnings;

my @strings = qw/foo BAR Baz blah q/;


foreach (@strings) {
    # leave string as is
    print ucfirst(reverse(ucfirst(reverse()))),"\n";    
    # or lc everything else
    print ucfirst(reverse(ucfirst(reverse(lc())))),"\n";

}
[download]

UPDATE: well that serves me right for not refreshing my browser, looks like I had the same idea as fruiture

grep

Mynd you, mønk bites Kan be pretti nasti...