The installation process for Red Hat Linux 6.0 includes the ability to upgrade from prior versions of Red Hat Linux (2.0 through 5.2, inclusive) which are based on RPM technology. Upgrading your system installs the modular 2.2.x kernel as well as updated versions of the packages that are installed on your machine. The upgrade process preserves existing configuration files using a .rpmsave extension (e.g., sendmail.cf.rpmsave) and leaves a log telling what actions it took in
/tmp/upgrade.log. As software evolves, configuration file formats can change, so you should carefully compare your original configuration files to the new files before integrating your changes.