Chapter 5. Package Management with RPM
The RPM Package Manager (RPM), is an open packaging system available for anyone to use, and works on Red Hat Linux as well as other Linux and UNIX systems. Red Hat, Inc. encourages other vendors to take the time to look at RPM and use it for their own products. RPM is distributable under the terms of the GPL.
For the end user, RPM provides many features that make maintaining a system far easier than it has ever been. Installing, uninstalling, and upgrading RPM packages are all one line commands, and all the messy details have been taken care of for you. RPM maintains a database of installed packages and their files, which allows you to perform powerful queries and verification of your system.
During upgrades, RPM handles configuration files specially, so that you never lose your customizations -- a feature that is impossible with straight .tar.gz files.
For the developer, RPM allows you to take source code for software and package it into source and binary packages for end users. This process is quite simple and is driven from a single file and optional patches that you create. This clear delineation of "pristine" sources and your patches and build instructions eases the maintenance of the package as new versions of the software are released.
 | Please Note |
|---|---|
Although it can be important to understand the concepts behind RPM, for those who prefer a graphical interface to the command line, we suggest you use Gnome-RPM. Please see Chapter 6 for more information. |
RPM Design Goals
Before trying to understand how to use RPM, it helps to have an idea of what the design goals are.
- Upgradability
With RPM you can upgrade individual components of your system without completely reinstalling. When you get a new release of an operating system based on RPM (such as Red Hat Linux), you don't need to reinstall on your machine (as you do with operating systems based on other packaging systems). RPM allows intelligent, fully-automated, in-place upgrades of your system. Configuration files in packages are preserved across upgrades, so you won't lose your customizations.
- Powerful Querying
RPM is also designed to have powerful querying options. You can do searches through your entire database for packages or just certain files. You can also easily find out what package a file belongs to and where it came from. The files an RPM package contains are in a compressed archive, with a custom binary header containing useful information about the package and its contents, allowing you to query individual packages quickly and easily.
- System Verification
Another powerful feature is the ability to verify packages. If you are worried that you deleted an important file for some package, simply verify the package. You will be notified of any anomalies. At that point, you can reinstall the package if necessary. Any configuration files that you modified are preserved during reinstallation.
- Pristine Sources
A crucial design goal was to allow the use of "pristine" software sources, as distributed by the original authors of the software. With RPM, you have the pristine sources along with any patches that were used, plus complete build instructions. This is a big advantage for several reasons. For instance, if a new version of a program comes out, you don't necessarily have to start from scratch to get it to compile. You can look at the patch to see what you might need to do. All the compiled-in defaults, and all of the changes that were made to get the software to build properly are easily visible this way.
This goal may only seem important for developers, but it results in higher quality software for end users too. We would like to thank the folks from the BOGUS distribution for originating the pristine source concept.