Chapter 36. Advanced Yum

Chapter 36. Advanced Yum

IN THIS CHAPTER

• Getting Started

• Using Yum to Remove Packages

• Using Yum to Manage Package Inventory

• Configuring Yum

• Creating a Local Yum Repository

• Reference

One of the main things you will want to do with Fedora is to install your own choice of software, as if you had not got enough choice with the packages available with Fedora! Although Fedora provides a useful graphical configuration tool for adding and removing software, it is limited to the software that is supplied with Fedora. This means that you can't add anything else except what Fedora wants you to have, neither can you upgrade if a new release of software becomes available. The Yum tool (Yellowdog Updater, Modified) has been included with Fedora since version 1 and has become the tool of choice for installing and updating applications. In this chapter, we will take a look at how Yum works, its basic usage, and more advanced package and repository management.

Yum is controlled entirely from the command line, so you will have to memorize some useful switches to get the most from it.

Before I go into Yum itself, it is worthwhile understanding what goes on behind the scenes. How does Yum actually work?

It is easiest to think of Yum as a software layer that utilizes the rpm command. When you issue commands to Yum, it automatically accesses various repositories and downloads the rpm headers that are then queried using the rpm command. The advantage to this is that all the processing takes place locally, without the need to download the entire RPM itself. Typically, the RPM header makes up a very small portion of the file, which makes it easy to handle and quick to download. Yum builds and maintains a local cache of header files, attributed to the supplying repository, and queries this when you use Yum. Each time Yum is invoked, it checks the repositories for any updates. If any are found, it adds new headers to its cache, thereby making it as up-to-date as possible when you need to use it. Because Yum uses rpm, there should be no dependency problems, making it a fast and easy way to install and update software.

Yum is primarily controlled by its configuration file, yum.conf, and by the contents of the yum.repos.d directory, both of which can be found in /etc. By default, Yum uses the Red Hat and Fedora repositories for updates, but you can easily add more of your own if you want to install other software that is not available from Red Hat themselves.

Like apt, Yum is incredibly easy to use, requiring a single command with a switch to update all the software in Fedora.