The Yum Client

If you are a systems administrator or Linux geek you've likely set up a repository of one sort or another for testing by now. Others, who have installed a pre-yummified distribution from one source or another and only want to know how to set up their yum clients, will have skipped the previous section altogether. Welcome back!

For starters, let's make sure that everybody has access to a yum repository, whether or not they built one. Chances are decent that if you installed yum from the main yum site:
http://linux.duke.edu/projects/yum
yum will ``work'' in that it will function at the client level if the client has access to the Internet and hence the default repositories in its /etc/yum.conf file. We will therefore begin by testing it.

As root, enter:

  # yum list

at the # command prompt in a tty window (for example, in an xterm). With luck, you will see something like:

rgb@lilith|T:7#yum -c /tmp/yum.conf list
Gathering header information file(s) from server(s)
Server: Yum Test
Finding updated packages
Downloading needed headers
Name                                Arch   Version                  Repo        
--------------------------------------------------------------------------------
xmlsysd                             i386   0.2.0-1                  yum-test    
...

where there can be a lot of packages in the list (I'm using a tiny two RPM repository with its own custom yum.conf in this example, as you can see, to avoid this). These are all packages that are on the repository but not yet installed on your system!

Don't be discouraged if instead of this you get some sort of error message, or even if error messages persist through several more of the steps outlined below. Yum is a very conservative program, and it tries very hard to never do anything that will break your system with a default action. Some of its warning messages (especially ones you will get if your RPM database is inconsistent or corrupted by the use of RPMs -force or -nodeps options to install packages in the past) should be fully resolved by ``cleaning up the system'' before yum will run without complaint. As noted above, yum is happiest when run on a clean install from a yummified distribution repository, and your system will remain happiest if only yum is used to add or remove only packages from a set of yummified repositories that are consistent with this initial distribution repository, except when yum itself is used to upgrade to a different one.

But how can we arrange for this to be so? And once we've made the arrangements, how can we use yum for routine installation and maintenance? The remainder of this section contains two subsections: one on yum.conf, yum's configuration file that tells it, among other things, where to look for RPM repositories, what order to use them in, and what kind of policy and security features you wish to use when installing or maintaining packages from them; and one on the yum client itself.