Technical Definition of RPM

Redhat Package Manager (RPM)

• What is an RPM?

RPM is also called as the Red Hat Package Management system. This is an freely published set of specifications and tools to allow Linux and Unix vendors to package their software in a way that is amenable to automated installation upgrade, removable and administration. Although it has Red Hat's name in it —- it has been adopted by most of the major Linux distribution maintainers.

• Basic Concepts of RPM

The RPM Package Manager (RPM) is a powerful command line driven package management system capable of installing, uninstalling, verifying, querying, and updating computer software packages. Each software package consists of an archive of files along with information about the package like its version, a description, and the like.

An RPM package will be of the form

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

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• Different Modes of Usage

Installation:

In the simplest form to install a package (foo version 1.2 in this example), you can use commands like:

rpm -i foo-1.2.rpm

rpm –ivh foo-1.2.rpm

Upgrading:

Suppose you have the package foo-1.2 installed. If you have the newer version of that package (say foo-1.3), then you can upgrade the package. This is how its done.

rpm -U foo-1.3.rpm

rpm –Uvh foo-e.1.2.rpm

Removing:

Suppose you have the package foo-1.2 installed. If you have this package.

rpm -e foo-1.3.rpm

Quering:

You can query a list of files from an installed package with

rpm -ql $SOME_INSTALLED_PACKAGE

list all of the packages that you have installed on the whole system

rpm -qa

You can also find out which package a given file "belongs to" with a command like:

rpm -qf /some/file/that/was/installed/by/something

You can search the installed package

rpm -qa | grep –i installed package name

To roll back the RPM transaction, use the —rollback option followed by the rollback target. If an hour after upgrading foo, you decide you don't want it, you could type:

rpm -Uvh --rollback '2 hours ago'

rpm -Uhv –-rollback ‘9:00 am’

rpm -Uhv –-rollback ‘december 25′

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yum install

Yellowdog updater modified (YUM)

Yum is a yellowdog updater modified . Yum is an automatic updater and package installer/remover for rpm systems. It automatically computes dependencies and figures out what things should occur to install packages. It makes it easier to maintain groups of machines without having to manually update each one using rpm. Yum has a plugin interface for adding simple features. Yum can also be used from other python programs via its module inteface. It was developed by Duke University to improve the installation of RPMs. yum searches numerous repositories for packages and their dependencies so they may be installed together in an effort to alleviate dependency issues. Red Hat Enterprise Linux 5.2 uses yum to fetch packages and install RPMs

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• Setting Up a yum Repository

Server end

1. Install the createrepo package.
2. Copy all the packages into one directory.
3. Run createrepo on that directory.This will create the necessary metadata for your yum repository.

Client end

Open the yum repository file in client end.

#vim /etc/yum.repos.d/rhel-debuginfo.repo

Edit this file & set the baseurl. Baseurl is yum server repodata patha & gpgcheck=0.

Yum Commands

yum commands are typically run as yum <command> <package name/s>. By default, yum will automatically attempt to check all configured repositories to resolve all package dependencies during an installation/upgrade.

The following is a list of the most commonly-used yum commands. For a complete list of available yum commands, refer to man yum.

yum install <package name/s>

Used to install the latest version of a package or group of packages. If no package matches the specified package name(s), they are assumed to be a shell glob, and any matches are then installed.

yum update <package name/s>

Used to update the specified packages to the latest available version. If no package name/s are specified, then yum will attempt to update all installed packages.

If the --obsoletes option is used (i.e. yum --obsoletes <package name/s>, yum will process obsolete packages. As such, packages that are obsoleted accross updates will be removed and replaced accordingly.

yum check-update

This command allows you to determine whether any updates are available for your installed packages. yum returns a list of all package updates from all repositories if any are available.

yum remove <package name/s>

Used to remove specified packages, along with any other packages dependent on the packages being removed.

Yum provides <file name>

Used to determine which packages provide a specific file or feature.

yum search <keyword>

This command is used to find any packages containing the specified keyword in the description, summary, packager and package name fields of RPMs in all repositories.

yum localinstall <absolute path to package name/s>

Used when using yum to install a package located locally in the machine.

• yum Options

yum options are typically stated before specific yum commands; i.e. yum <options> <command> <package name/s>. Most of these options can be set as default using the configuration file.

The following is a list of the most commonly-used yum options. For a complete list of available yum options, refer to man yum.

-y Answer "yes" to every question in the transaction.

-t Sets yum to be "tolerant" of errors with regard to packages specified in the transaction. For example, if you run yum update package1 package2 and package2 is already installed, yum will continue to install package1.

• Configuring yum

By default, yum is configured through /etc/yum.conf. The following is an example of a typical /etc/yum.conf file:

[main]

cachedir=/var/cache/yum

keepcache=0

debuglevel=2

logfile=/var/log/yum.log

distroverpkg=redhat-release

tolerant=1

exactarch=1

obsoletes=1

gpgcheck=1

plugins=1

metadata_expire=1800

[myrepo]

name=RHEL 5 $releasever - $basearch

baseurl=http://local/path/to/yum/repository/

enabled=1

A typical /etc/yum.conf file is made up of two types of sections: a [main] section, and a repository section. There can only be one [main] section, but you can specify multiple repositories in a single /etc/yum.conf.

[main] Options

The [main] section is mandatory, and there must only be one. For a complete list of options you can use in the [main] section, refer to man yum.conf.

The following is a list of the most commonly-used options in the [main] section.

Cachedir

This option specifies the directory where yum should store its cache and database files. By default, the cache directory of yum is /var/cache/yum.

keepcache=<1 or 0>

Setting keepcache=1 instructs yum to keep the cache of headers and packages after a successful installation. keepcache=1 is the default.

reposdir=<absolute path to directory of .repo files>

This option allows you to specify a directory where .repo files are located. .repo files contain repository information.

If reposdir is not set, yum uses the default directory /etc/yum.repos.d.

gpgcheck=<1 or 0>

This disables/enables GPG signature checking on packages on all repositories, including local package installation. The default is gpgcheck=0, which disables GPG checking.

If this option is set in the [main] section of the /etc/yum.conf file, it sets the GPG checking rule for all repositories. However, you can also set this on individual repositories instead; i.e., you can enable GPG checking on one repository while disabling it on another.

assumeyes=<1 or 0>

This determines whether or not yum should prompt for confirmation of critical actions. The default if assumeyes=0, which means yum will prompt you for confirmation.

If assumeyes=1 is set, yum behaves in the same way that the command line option -y does.

tolerant=<1 or 0>

When enabled (tolerant=1), yum will be tolerant of errors on the command line with regard to packages. This is similar to the yum command line option -t.

The default value for this is tolerant=0 (not tolerant).

• Repository Options

The [repository] section of the /etc/yum.conf file contains information about a repository yum can use to find packages during package installation, updating and dependency resolution. A repository entry takes the following form:

You can also specify repository information in a separate .repo files (for example, rhel5.repo). The format of repository information placed in .repo files is identical with the [repository] of /etc/yum.conf.

.repo files are typically placed in /etc/yum.repos.d, unless you specify a different repository path in the [main] section of /etc/yum.conf with reposdir=. .repo files and the /etc/yum.conf file can contain multiple repository entries.

Each repository entry consists of the following mandatory parts:

[repository ID]

The repository ID is a unique, one-word string that serves as a repository identifier.

name=repository name

This is a human-readable string describing the repository.

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