$cfg{invalid_characters_re} = '[' . quotemeta($cfg{invalid_characters}) . ']' if $cfg{invalid_characters};
$cfg{special_characters} = '!@#$%^&*()_+=[]{}<>\'"|\\,;.:?-';
$cfg{special_characters_re} = '[' . quotemeta($cfg{special_characters}) . ']';
$cfg{invalid_characters_re} = '[' . quotemeta($cfg{invalid_characters}) . ']' if $cfg{invalid_characters};
$cfg{special_characters} = '!@#$%^&*()_+=[]{}<>\'"|\\,;.:?-';
$cfg{special_characters_re} = '[' . quotemeta($cfg{special_characters}) . ']';