use locale;

use POSIX qw/locale_h/;
setlocale(LC_CTYPE, "sv");

my $search_str = "gläd";
my $item_str = "GLÄD";

if ($item_str =~ /^$search_str$/i) {
    print "Matched!";
}

##</code><code>##

locale -a
nlsinfo
ls /usr/lib/nls/loc
ls /usr/lib/locale
ls /usr/lib/nls