Linux has an excellent utility called RPM (Red Hat Package Manager) that makes it painless to install, uninstall, and upgrade software packages. Software distributed in an RPM package comes as a compressed archive, with a special header file that gives information about the package, such as its name, description, version number, size, and author.

Although RPM was created by Red Hat Software, it is available for anyone to use and works on other Linux and Unix systems. The RPM package format has become widely used in recent years and is now the de-facto standard for software distribution in the Linux arena.

RPM Features

Here are some of the features that make RPM so useful and popular.

Intelligent Upgrades

RPM makes it possible to upgrade individual components of your system without completely reinstalling everything. For example, when a new version of the Red Hat Linux operating system is released, you don't have to reinstall the entire system as you do with most other operating systems. Since RPM maintains a database of all the software installed on your system, it can perform intelligent upgrades of your system, replacing old packages with updated versions and removing obsolete ones. Your configuration files are preserved in the process, so you won't lose your customizations.

Package Querying

RPM has many powerful querying options, so you can easily search to find out what software is installed on your system or what package a file belongs to or to get a list of files that belong to a certain package.

System Verification

If you think you may have accidentally deleted a file belonging to a certain package, you can use RPM to verify the package. If RPM finds anything amiss, you can reinstall the package without disturbing any configuration files that you have modified.

Why Use RPM?

Before RPM was developed, most Unix software packages were distributed as compressed tar files, and this arrangement is still fairly common. But if you install software that comes packaged this way, you run certain risks and lose some potential benefits:

· What if the new package overlays certain files that other packages depend upon, and the new version is not compatible with the old one? You could end up rendering one or more packages useless.

· What happens if you want to remove the package from your system? It can be a real nuisance to find all the files associated with a package and manually remove them, without affecting other software that shares common files.

· What if the new version of PandaCalc replaces all your customization files with default versions? You'll have to do all that work again.

RPM solves all these problems--by warning you when new packages may affect existing ones, by providing an intelligent uninstall feature, and by preserving your customization files during upgrades. If you're thinking of downloading and installing some new software, always check to see if an RPM version is available first, and you'll save yourself some trouble later on.

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