tag link by tag name in a shortcode

I need to get the permalink of a specified tag by it’s name in the WordPress shortcode function, the shortcode look like so:

function shortcode_hashtag($attr, $content){
  $tagId = get_term_by('name', do_shortcode($content), 'tag');
  return '<a href="'.get_tag_link($tagId).'" title="">'.do_shortcode($content).'</a>';
}

add_shortcode('hash', 'shortcode_hashtag');