RPM is the Red Hat Package Manager, developed by Red Hat Software. It's a packaging format used in several Linux distributions, such as Red Hat, Mandrake, Caldera OpenLinux, and TurboLinux. The RPM homepage is at http://www.rpm.org.
Since RPM is a package manager, you can install, remove, build, rebuild, and view your packages. In this document I will cover everything except building RPM software packages, which you probably won't need to do right now.
Your Linux distribution, if it uses RPM, already installed RPM packages. You can install additional RPMs from your CD-ROM or download them from an FTP server. RPM packages end in ".rpm".
The most basic syntax for installing an RPM package is rpm -i package-1.2.3-4.i386.rpm. RPM file names usually consist of the package name ("package"), the version ("1.2.3"), the build number or patch level by Red Hat ("4"), the architecture it was built to run on, ("i386"), and the "rpm" extension.
Instead of using just "-i" in the RPM command line to install RPMs, you probably want to use "-ivh" so you can see what's going on.
Sometimes you have to force a package to install, because maybe you had it installed, but some of its files got deleted and you want to have the complete package again. Simply add "--force" to your RPM command line while installing a package. If you don't, you'll probably get complaints that the package is already installed.
If you're forcing a package to install, your command line will then look something like rpm -i --force package-1.2.3-4.i386.rpm. Forcing a package to install usually won't hurt anything, but don't use the "--force" option all the time.
Often, new versions of software come out, and new RPM packages are built for them. That's when the "-U" flag of RPM becomes useful. That's a capital "U", not a lowercase "u".
If there's an update to the previous package we had, it would be noted in the filename. So an upgrade to "package-1.2.3-4.i386.rpm" would be something like "package-2.0.3-1.i386.rpm". To install it, the command line looks like rpm -U package-2.0.3-1.i386.rpm.
Like installing, you can also see more of what's going on. Instead of just "-U" you can use "-Uvh".
A lot of the time, it may be hard to figure out what program to run after installing the RPM package for it. Using rpm -ql packagename will give you a list of all the files that are part of the package. This may be useful also for finding where its default configuration file is located.
It may also help to pipe the output through less, if there are a lot of files in the package. Simply type rpm -ql packagename | less. less is cool, and it is your friend.
If you don't want to have a package around anymore, you can remove it. Use the "-e" flag for rpm. Let's say we want to remove the package installed by package-1.2.3-4.i386.rpm. Don't type the entire filename. Just type something like rpm -e package-1.2.3-4. Even rpm -e package-1.2.3 will work, if there aren't more RPM packages of package-1.2.3 lying around, which may have been installed with the "--force" flag.
Many RPM packages depend on other RPM packages to run. A lot of cases are programs that need libraries to run, or programs that need other programs to run. It's generally a bad idea to remove packages without paying attention to what depends on those packages, which RPM warns you about on default, unless you use the "--nodeps" flag.
RPM will also complain about dependencies if you try to upgrade a bunch of packages. Upgrading also involves removing the old package, so you can use the "--nodeps" flag with upgrading as well.
To get a simple printout of all the packages you have installed through RPM, use the command rpm -qa. It's as simple as that.
To see what packages you have installed, use their names to find them. For example, if we want to find all RPM packages installed that have "pack" somewhere in their names, we type rpm -qa | grep pack.
What we're doing there is printing out all the packages but sending it to the grep program so that grep can search for the text string we specified ("pack").
To find out information about our package, type rpm -qi package-1.2.3. The "-q" we've been using so far stands for Query, and the "i" stands for Information.
Here's a sample output from a package called "perl":