How does yum determine what package is newer with multiple repositories enabled?

Question

I am trying to understand how yum is able to determine a particular package is newer when the system has multiple repositories enabled and a particular package may be available in one or all of the repos.

We are trying to create a custom package management system in order to manage our local repos and report to us if there are new updates available on all the servers vs what is available on the local repos.

Answer 1

yum looks for the "newest" version and release for a given package name. It checks version first, and then release. If you give multiple repositories which have the same package name, yum will use the "newest" version (and release).

A comment by @msuchy mentions rpmdev-vercmp which you may find useful for analysis of RPM files.

Further reading:

• Packaging:NamingGuidelines
• What's the meaning of the number which appears sometimes (when I use yum to install a fedora package) before a colon at the beginning of the name of the package?
• How to programmatically determine the highest version kernel RPM installed?
• Comparing RPM versions in the shell