# Remove all the yum metadata from the system
yum clean all
# Make a working directory and go there
mkdir /root/centos
cd /root/centos/
# Check the version and architecture of RHEL
# currently installed
cat /etc/redhat-release
uname -i
# Download the following 4 RPM files and 1 RPM-GPG-KEY file
# from http://mirror.umd.edu/centos/{VER}/os/{ARCH}/
# In this example, we are converting RHEL 6.1 x86_64. We will
# use the latest available version of the following packages.
wget http://mirror.umd.edu/centos/6.2/os/x86_64/Packages/centos-release-6-2.el6.centos.7.x86_64.rpm
wget http://mirror.umd.edu/centos/6.2/os/x86_64/Packages/yum-3.2.29-22.el6.centos.noarch.rpm
wget http://mirror.umd.edu/centos/6.2/os/x86_64/Packages/yum-utils-1.1.30-10.el6.noarch.rpm
wget http://mirror.umd.edu/centos/6.2/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.30-10.el6.noarch.rpm
wget http://mirror.umd.edu/centos/6.2/os/x86_64/RPM-GPG-KEY-CentOS-6
# Import the GPG signing key
rpm --import RPM-GPG-KEY-CentOS-6
# Remove the following RPMS from the system
rpm -e --nodeps redhat-release-server
rpm -e yum-rhn-plugin rhn-check rhnsd rhn-setup rhn-setup-gnome
# If the second rpm command fails because a package is not installed,
# remove the name of that package from
# the command line and re-run the command.
# Force install all 4 RPMS in the working directory
rpm -Uvh --force *.rpm
# Do a yum upgrade. It should go to a CentOS download site and ask
# to upgrade a lot of packages
yum upgrade
# Reboot the system
shutdown -r now
