Red Hat ENTERPRISE LINUX 5 - DEPLOYMENT Deployment Manual page 167

Chapter 12.
YUM (Yellowdog Updater Modified)
Yellowdog Update, Modified (YUM) is a package manager that 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.
up2date is now deprecated in favor of yum (Yellowdog Updater Modified). The entire stack of tools
which installs and updates software in Red Hat Enterprise Linux 5.2 is now based on yum. This
includes everything, from the initial installation via Anaconda to host software management tools like
pirut.
yum also allows system administrators to configure a local (i.e. available over a local network)
repository to supplement packages provided by Red Hat. This is useful for user groups that use
applications and packages that are not officially supported by Red Hat.
Aside from being able to supplement available packages for local users, using a local yum repository
also saves bandwidth for the entire network. Further, clients that use local yum repositories do not
need to be registered individually to install or update the latest packages from Red Hat Network.
12.1. Setting Up a yum Repository
To set up a repository, follow these steps:
Procedure 12.1. Setting Up a yum Repository
1. Install the createrepo package.
2. Copy all the packages into one directory (for example, /mnt/local_repo).
3. Run createrepo on that directory (for example, createrepo /mnt/local_repo). This will
create the necessary metadata for your yum repository.
12.2. yum Commands
yum commands are typically run as yum
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.
<command> <package name/s>. By default, yum will
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