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Posts Tagged ‘rhel’

Abusing Yum to Downgrade to a Specific Update in RHEL

January 28th, 2013 by chwilk

Sometimes it just doesn’t pay to keep your machines up to date…

In the case that you must force a machine back to a previous update of RHEL (e.g. latest X.Y introduces a bug, and you want to revert to X.(Y-1) ), it isn’t easy to drop an update.

In Fedora, (and copied to RHEL, but somewhat useless by default) you can use something to the effect of

yum --releasever=X-1 distro-sync

Unfortunately, this only works for major version shifts.

If you want to do this in RHEL to hit a specific point release, you must play with some repos.

These instructions assume you have a satellite and can create kickstart profiles therein.

Edit a kickstart profile and set it back to the release you want. Also select any extra repositories you may have access to (e.g. supplementary, optional) then look at the kickstart script it generates. Find the URL for install and any repo you’ve added, then create a .repo file in /etc/yum.repos.d/ for those repositories. Name each repo in a globbable format, e.g. rhel-downgrade-X-Y rhel-downgrade-X-Y-optional…

Now the moment of truth.

yum --disablerepo \* --enablerepo rhel-downgrade-X-Y\* distro-sync

You can also specify specific yum groups and individual rpms on the command line to just downgrade a particular subsystem, as long as it doesn’t have firm dependencies into the rest of the OS.