RedHat Package Manager

By Joshua Erdman
Digital Foundation, inc.

In the article, RedHat Installation, I discussed that you need to choose the packages you want to install. Well With RedHat Package Manager, you can maintain, remove, or install packages well after your Linux installation. These packages are wrapped up into an RPM file. The RPM file contains everything you need to get this specific piece of software to work on your system. Before we go into more detail, let's go over some software background.

Original Software Installations

Linux is originally a programming and Compiling environment. Before RPMs existed, you would have to download the software's source code. There you would find the INSTALL file and you read about all the other requirements or software dependencies before ou could successully compile you are intending to install.

A great example of this was installing Apache. Before RPMs I would download the Apache source code. The INSTALL text file would list all the dependencies, one of those being SASL (an encryption software package for for SSL communication or secure pages). So before I could even begin the Apache install, I would have to hunt down the SASL package and see if it needed any dependencies. Typically just finding all the needed packages and getting then installed would take a few hours. Usually I need to install 2 or 3 of them before I could get the package I originally wanted to compile right. And do not forget, compiling these packages is another article. You would have to provide various install flags and do some steps that definitely would appear cryptic to a newbie.

Enter the RPM

RPMs, some people love them; some people hate them. Well RedHat came up with the idea of RPMs. In the Package a list of of other dependencies is maintained and all the files needed are already compiled This sae a lot of time and headaches. Even better, these packages can be downloaded from the RedHat website for free. Installation is simple, you obtain the RPM file, make sure you have root access and then type:

rpm -i <file>.rpm

If any dependencies are missing, you will be notified and then you must obtain the other needed package(s).

What some people do not like about RPMs is that you loose the ability to have certain features activated on compile time. It doesn't always mean that these features do not exist but they may need to be loaded as a module which could be a bit slower than if they were compiled in. Another reason is that the source code for most software is updated more frequently than the RPM. If you need the absolute newest version, you will not be able to get that from an RPM. Reguardless, RPMs are usually updated often enough to keep your systems safe as long as you apply the newer RPMs when they become available. The RPM lagtime between when code was written could be between two weeks and a couple of months. This usually depends on the importance of the update and how popular the package is.

Red Carpet

This is another package manager that runs in X Windows. It has a great interface with automatic capabilities to download RPMs and install them. You can even instruct it to automatically download any needed dependencies. This is a great tool if you plan on keeping your system's packages up to date.

Package Update Notification

RedHat has created a proactive approach to keeping your systems updated, the RedHat Network. A low cost subscription to this network allows your system configuration and all installed packages to be monitored. In the event of newly discovered security vulnerabilities that may affect your system, you can set up RHN to notify you by e-mail. From this web portal, you can monitor your system, by one-click update all important packages, install new packages, and remove others. This is a very complete site and I definitely recommend it for anyone who keeps a Linux box on the Internet.

References
More RPM stuff

Article last reviewed: 02/12/2003

Created by: Digital Foundation, inc.

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