You can display a mobile version using canonical and rel alternate tags , desktop version showing the alternate tag and mobile version showing the canonical tag. When serving dynamic HTML on the same URL you should use the vary HTTP header. 

Google explains this in detail:

https://developers.google.com/webmasters/smartphone-sites/details

What is Google's policy about separate content on same URLs in mobile and desktop versions?
I was wondering why od(1) used to work in UNIX but doesn't work in GNU/Linux. There is a nice answer on serverfault. The next question is, are you aware of any tools that can emulate od behavior to support dumping directory data in GNU/Linux?
