I really wish I had access to my `/ets/hosts` file on natively iOS so I could block Facebook from there like I do on my laptop.
# Block Facebook
127.0.0.1 www.facebook.com 127.0.0.1 facebook.com 127.0.0.1 static.ak.fbcdn.net 127.0.0.1 www.static.ak.fbcdn.net 127.0.0.1 login.facebook.com 127.0.0.1 www.login.facebook.com 127.0.0.1 fbcdn.net 127.0.0.1 www.fbcdn.net 127.0.0.1 fbcdn.com 127.0.0.1 www.fbcdn.com 127.0.0.1 static.ak.connect.facebook.com 127.0.0.1 www.static.ak.connect.facebook.com
Taken from http://cariblogger.com/2010/07/how-to-block-facebook-using-h...
For OS X implementation, see the comment https://news.ycombinator.com/item?id=11795351 and the linked implementation.
For GNU/Linux, no one seemed to have posted something and I could not easily find it. Hence I wrote my own that has been tested successfully on my own machine: https://github.com/gajjanag/config_files/blob/master/block_f....