.htaccess - How to block an empty user agent request -

is there solution preventing http request has empty user agent string preferably using .htaccess?

#redirect empty user agent, unless it's accessing rss feed rewritecond %{http_user_agent} ^$  rewritecond %{request_uri} !^/rss.php # <-- path rss.php rewriterule .* http://%{remote_addr}/ [r,l] 

source: http://wiki.e107.org/index.php?title=htaccessexample