Package Management With Rpm; Rpm Design Goals - Red Hat ENTERPRISE LINUX 4 System Administration Manual

Chapter 15.

Package Management with RPM

The RPM Package Manager (RPM) is an open packaging system, available for anyone to use, which
runs on Red Hat Enterprise Linux as well as other Linux and UNIX systems. Red Hat, Inc encourages
other vendors to use RPM for their own products. RPM is distributable under the terms of the GPL.
For the end user, RPM makes system updates easy. Installing, uninstalling, and upgrading RPM
packages can be accomplished with short commands. RPM maintains a database of installed
packages and their files, so you can invoke powerful queries and verifications on your system. If you
prefer a graphical interface, you can use the Package Management Tool to perform many RPM
commands.
During upgrades, RPM handles configuration files carefully, so that you never lose your
customizations — something that you cannot accomplish with regular .tar.gz files.
For the developer, RPM allows you to take software source code 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 between pristine sources and your patches
along with build instructions eases the maintenance of the package as new versions of the software
are released.
Note
Because RPM makes changes to your system, you must be root to install, remove, or
upgrade an RPM package.

15.1. RPM Design Goals

To understand how to use RPM, it can be helpful to understand RPM's design goals:
Upgradability
Using 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
Enterprise Linux), you do not 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 do not lose
your customizations. There are no special upgrade files needed to upgrade a package because
the same RPM file is used to install and upgrade the package on your system.
Powerful Querying
RPM is designed to provide powerful querying options. You can do searches through your entire
database for packages or just for certain files. You can also easily find out what package a file
belongs to and from where the package came. 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, verify the package. You are notified of any anomalies. At that
point, you can reinstall the package if necessary. Any configuration files that you modified are
preserved during reinstallation.
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