yum

Documentation:

• access.redhat.com/…tories.html
• www.centos.org/…yum/index.html
• from Redhat:
  To define a new repository, you can either add a [repository] section to the /etc/yum.conf file, or to a .repo file in the /etc/yum.repos.d/ directory. All files with the .repo file extension in this directory are read by yum, and it is recommended to define your repositories here instead of in /etc/yum.conf.

You can install repository priorities: wiki.centos.org/…um/Priorities

But a better solution might be to leave the extra repos disabled in the yum configuration and install/update the packages you want from them with:

yum --enablerepo=reponame install packagename

• see www.thegeekstuff.com/…examples for examples
• otherwise:
  “What ends up happening is that you have multiple repositories that provide the same thing, sometimes under different names. You end up mixing dependencies between repositories, so some things are protected, some pull in deps from the wrong repository... fire and brimstone, dead rising from graves, dogs and cats start living together. The whole mess introduces some really odd logic edge cases for yum that should in theory never be encountered. It’s basically a software solution to a management problem.”

Working with yum, an intro from IBM: www.ibm.com/…-102-5/index.html

Removing Old Kernels

• to remove old kernels, first check current:

uname -r

yum list kernel.* #find what's installed

yum remove kernel-2.6.18-8.1.15.el5 #remove old

• see www.howtoforge.com/…thread.php
• for ubuntu, see: jaypeeonline.net/…untu-kernels
• To upgrade to php 5.2, see: wiki.centos.org/…HP_5.1_To_5.2
• to see what repositories are in use, add to conf: showdupesfromrepos=1
  vi /etc/yum.conf
• you can also:

yum list --showduplicates all php

• add repoquery with:

yum install yum-utils
repoquery -i php