YUM Tips

Yellow dog Updater, Modified (Yum) is the default package manager used in RHEL4 ( and clones like ScientificLinux and CentOS ). It is used to install and update packages from the official and 3rd party Repositories.

URL's that might come in handy:

• Yum Home page : http://linux.duke.edu/projects/yum/
• Yum Bugzilla : https://devel.linux.duke.edu/bugzilla/
• Yum Wiki ( contains an FAQ specific to Yum ) : http://wiki.linux.duke.edu/Yum
• Repositories for APT and YUM

In order to enable the automatic update system run following commands:

chkconfig --add yum-autoupdate
service yum-autoupdate start

In order to disable the system run:

service yum-autoupdate stop
chkconfig --del yum-autoupdate

Additional extensions to yum update system are distributed in following packages: yum-autoupdate, yum-installonlyn, yum-versionlock, yum-tsflags, yum-changelog, yum-protectbase and yum-utils.

These plugins are highly recommended for users who are using the default update method.

• yum-protectbase: This plugin allows certain repositories to be protected. Packages in the protected repositories can't be overridden by packages in non-protected repositories even if the non-protected repo has a later version.
• yum-versionlock: This plugin allows certain packages specified in a file to be protected from being updated by newer versions.

The purpose of the protectbase plugin is to protect certain repositories from updates from other repositories. Repositories that are to be protected will not be updated by newer files from unprotected repositories. This plugin is recommended for anyone who routinely enables 3rd party repositories, as these non-SL4 repositories may update certain system files, potentially causing your SL4 installation to become unstable.

yum install -y yum-protectbase

After the plugin is installed, you need to edit all .repo files in /etc/yum.repos.d/ and add either:

protect=1

or

protect=0

for each repository.

Note: You MUST add protect=0 to all repos in all .repo files or any repos that you have in /etc/yum.conf if you want them unprotected, otherwise they belong to the protect=1 group.

When doing updates after editing your files, only repositories that have the protect=1 stanza can update other protect=1 repositories.

cat /etc/yum.repos.d/dag.repo
[dag]
name=DAG (http://dag.wieers.com) additional RPMS repository
baseurl=http://linuxsoft.cern.ch/dag/redhat/el4/en/i386/dag
enabled=1
protect=0

cat /etc/yum.repos.d/sl4.repo
[sl4-base]
name=Scientific Linux 4 (SL4-i386) base
baseurl=http://linuxsoft.cern.ch/scientific/4x/i386/apt/RPMS.os/
enabled=1
protect=1

[sl4-updates]
name=Scientific Linux 4 (SL4-i386) updates
baseurl=http://linuxsoft.cern.ch/scientific/4x/i386/apt/RPMS.updates/
enabled=1
protect=1

[sl4-contrib]
name=Scientific Linux 4 (SL4-i386) contrib
baseurl=http://linuxsoft.cern.ch/scientific/4x/i386/apt/RPMS.contrib/
enabled=1
protect=1

This plugin prevents packages from getting upgraded beyond given version. The packages are defined in the file /etc/yum/pluginconf.d/versionlock.list. The versionlist is in the format of 'rpm -qa'

yum install yum-versionlock

Put all packages that have to be locked in the file /etc/yum/pluginconf.d/versionlock.list, for example:

rpm -qa |grep bash|sort >> /etc/yum/pluginconf.d/versionlock.list

You need to delete the package entry from /etc/yum/pluginconf.d/versionlock.list to upgrade it.

rpm -qa | grep glite | sort >> /etc/yum/pluginconf.d/versionlock.list
rpm -qa | grep ^ig | sort >> /etc/yum/pluginconf.d/versionlock.list