RPM Package Manager

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(Redirected from Red Hat Package Manager)

Image:RPM Logo.jpg RPM Package Manager (or RPM, originally called "Red Hat Package Manager") is a package management system primarily intended for Linux. RPM installs, updates, uninstalls, verifies and queries software. RPM is the baseline package format of the Linux Standard Base. Originally developed by Red Hat for Red Hat Linux, RPM is now used by many Linux distributions. It has also been ported to some other operating systems such as Novell NetWare (since version 6.5 SP3) and IBM AIX since version 5, see RPM homepage for all supported platforms. "RPM", as it is used today, is an example of a recursive acronym.

1 The RPM database
2 Package label
3 Advantages and disadvantages of the format
4 Creating RPMs
5 Supported Linux distributions
6 Related tools
7 External references and links

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The RPM database

Working behind the scenes of package manager is the RPM database. It consists of a doubly-linked list that contains all information for all installed packages. The database keeps track of all files that are changed and created when a user installs a program and can therefore very easily remove the same files. If the database gets corrupted (which happens easily if the RPM client is killed), the double links ensure that it can often be rebuilt without any trouble. On Red Hat systems the database is stored in /var/lib/rpm.

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Package label

Every RPM package has a package label, which contains the following pieces of information:

the software name
the software version (the version taken from original "upstream" source of the software)
the package release (the number of times the package has been rebuilt using the same version of the software) this field is also often used for indicating the specific distribution the package is intended for by appending strings like "mdk" (Mandriva Linux), "fc4" (Fedora Core 4), "rhl9" (Red Hat Linux 9), "suse100" (SUSE Linux 10.0) etc.
the architecture the package was built under (i386, i686, athlon, ppc, etc.)

and the RPM file would normally have the following format:

<name>-<version>-<release>.<arch>.rpm

An example:

nano-0.98-2.i386.rpm

However, note that package label is contained within the file and does not necessarily need to match the name of the file. Source code may also be distributed in RPM packages. Such package labels do not have an architecture part and replace it with "src". E.g.:

libgnomeuimm2.0-2.0.0-3.src.rpm

Additionally, libraries are distributed in two separate packages for each version. One containing the precompiled code and one containing the development files such as header files etc. for the library in question. Those packages have "-devel" appended to their name field. Users need to carefully check so that the version of the development package matches that of the binary package, otherwise the library may very well not work.

RPM files with the noarch.rpm extension refer to files which do not depend on a certain computer's architecture. These files usually include graphics and text for another program to use.

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Advantages and disadvantages of the format

Advantages of using RPM packages over other ways to acquire and install software often cited are:

A uniform way for the user to install programs.
Simple to uninstall programs.
Popularity: lot of packages available, even though they often need recompilation to work in another distribution.
Non-interactive installation: makes it easy to automate installation.
Original source archive (e.g. .tar.gz, .tar.bz2) included: easy to verify.
Cryptographic verification with GPG and md5.
DeltaRPMs, which are RPM's equivalent of a patch file, combine themselves with installed RPMs to perform updates on software that was installed by RPM. This is a much more convenient way to update RPM-installed software, since DeltaRPM doesn't require the original package to perform the update.

Disadvantages often cited include:

Often has backwards incompatible changes in package format.
Incomplete and outdated documentation.
Packaging typically has a shallow learning curve.
Sometimes contradictory package version dependencies, varying by which Linux distribution is using RPM.
Cannot be unpacked with ordinary tools like deb and tgz packages (though the rpm source tarball includes a shell script - rpm2cpio.sh[1] - that extracts the cpio archive part from an rpm using only od, expr, dd and gunzip).

RPM has also been criticized for a lack of consistency in package names and content, which can make automatic dependency handling difficult. However, this is not a problem inherent in the RPM format, but rather a problem of co-ordination amongst major distributions who use RPM in packaging such as Red Hat Linux, SuSE and Mandriva Linux. When using packages that are from a particular distribution (say Red Hat Linux) or built for a particular distribution (for example Freshrpms [2] for Red Hat Linux), then automatic dependency checking can work, using tools such as yum or apt (see below). A tool exclusively for Mandriva Linux is urpmi, and can help with the so called 'dependency hell'.

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Creating RPMs

The "recipe" for creating an RPM package is a spec file. Spec files end in the ".spec" extension and contain the package name, version, RPM revision number, steps to build, install, and clean a package, and a changelog. Multiple packages can be built from a single RPM spec file, if desired. RPM packages are created from RPM spec files using the rpmbuild tool.

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Supported Linux distributions

Several Linux distributions support RPM. These include, but are not limited to:

(See also: List of Linux distributions.)

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Related tools

RPM is often used by another tool for handling dependencies, such as the Yellow Dog Updater Modified (yum) or the RPM-based version of the Advanced Packaging Tool (apt).

Some other package managers are