HowtoMatrix

Simple enough, add an exclude line to the end of your [main] section in /etc/yum.conf , and you are done. Your yum.conf should look something like this:
[main]
cachedir=/var/cache/yum
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
installonly_limit=3
exclude=gdm pidgin

This will prevent upgrades of the gdm package as well as pidgin. The list of apps in the exclude should be space sepeated.

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