How are configuration files handled during an RPM upgrade?
FreeRADIUS contains many configuration files under the FreeRADIUS configuration directory /etc/raddb. RPM has special support for configuration files because configuration files are designed to be modified after installation. During an RPM update all the files in the new package are copied into their destination directories. If RPM was ignorant about configuration files it would overwrite the configuration files which might have been carefully tailored to the installation. If that were the case then upgrading to a new package version would erase the careful customizations implemented by the system administrator, clearly this is not desired behavior. To overcome this problem the author of the rpm spec file can mark files as being a configuration file. This is done with the %config tag in the spec file and causes RPM to process the file specially during an upgrade. If the configuration file has not been modified prior to the upgrade then RPM simply overwrites the on-disk copy of the file
