How are OS updates handled by default in FC5?

[Boris Glawe]

The system ist always updated with yum. Yum downloads rpm files and 
installes them. It's not really a frontend for the rpm command, as it 
manipulates the rpm database directly instead of calling the rpm 
command. Anyway the result is always the installation/update of normal 
rpm files.

The dependencies between rpm files are described by xml files, which 
have to reside in a directory called repodata. Actually the existence of 
this directory containing the description files makes a normal directory 
with rpm files to a yum repository. if you'd like to install a program, 
that requires another program or library, yum will  detect this 
dependency with the help of these xml files and will automatically 
download an install the required rpm files.

You will not have to create these xml descriptions files by hand if 
you're going to setup your own repository. This can be done with the 
command createrepo on the serverside. createrepo examines all rpm files 
in the current directory and subdirectories and generates the 
corresponding dependency description. It creates the repodata directory 
automatically.
If you mirror a repository (that is the directory hierarchy containing 
the rpm files and this repodata directory), you will not have to run 
this repodata command, as it's already provided by the mirror server.

If you create your own rpm files, you will always have to run createrepo 
each time you add an updated or new rpm file to you repository/directory.

On the client side you will only have to run "yum -y update", either 
manually or by a cronjob. The latter is the solution chosen by fedora.
Of course the URL of the repository must be specified in a file with the 
suffix ".repo" in /etc/yum.repos.d . Use the already existent repo files 
as an example how these files look like. The syntax is very easy.

greets Boris