yum install -y yum-priorities

vi /etc/yum.repos.d/CentOS-Base.repo

priority=1

rpm -ivh http://mirrors.ustc.edu.cn/fedora/epel/6/x86_64/epel-release-6-8.noarch.rpm

rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6

vi /etc/yum.repos.d/epel.repo

priority=2

rpm -ivh http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm

vi /etc/yum.repos.d/rpmforge.repo

priority=3

rpm -ivh http://download1.rpmfusion.org/free/el/updates/6/x86_64/rpmfusion-free-release-6-1.noarch.rpm

vi /etc/yum.repos.d/rpmfusion-free-updates.repo

priority=4

vi /etc/yum.repos.d/rpmfusion-free-updates-testing.repo

priority=4

yum check-update