There is a couple of great guides on installing Asterisk on both CentOS 6 & Ubuntu 12.  Follow the tutorial & do yourself.

CentOS: http://blogs.digium.com/2012/11/05/how-to-install-asterisk-11-on-centos-6/

Ubuntu: http://blogs.digium.com/2012/11/14/how-to-install-asterisk-11-on-ubuntu-12-4-lts/

If you intend to run Asterisk, we recommend you select one of those platforms and follow the instructions in one of the guides above.