I think you are reversing your strings and patterns. Try matching $users to the search pattern. Here's how to do it safely.

Do you have a restricted set of characters for your users? Let's assume it's word characters.:

my $search = param('search');
$search =~ tr/_0-9A-Za-z//cd;
$search = qr/\Q$search\E/i; # case insensitive match
for (@users) {
    print $_, '<br/>' if /$search/;
}
# or else:
# print map {($_,'<br/>')} grep {/$search/} @users;
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By transliterating away nonword characters, we really don't need the \Q..\E pair in the regex, but it doesn't hurt, and your data may be a little different.

After Compline,
Zaxo