How2CentOS posted an upgrade guide from CentOS 5.5 to CentOS 5.6

Before upgrading CentOS 5.5 to 5.6 it cannot be stressed enough how important it is to make a backup of your system before you do this. Actions listed in this post are written with the assumption that they will be executed by the root user running the bash or any other modern shell.

  Upgrading CentOS 5.5 to CentOS 5.6