最开始的是这样的：

1  cd /etc/yum.repos.d/2  ls

显示如下内容：

CentOS-Base.repo  CentOS-Debuginfo.repo  CentOS-Media.repo  CentOS-Vault.repo

开始添加新的源

一、安装CentOS yum源优先级插件yum-priorities 

yum install yum-priorities

二、设置CentOS默认yum源的优先级为最高

1 cd  /etc/yum.repos.d/ 2 vi CentOS-Base.repo

在[base]、[updates]、[extras]组下面添加priority=1，在[centosplus]、[contrib]组下面添加priority=2

备注：priority的优先级为1到99，设置为1即优先级最高，1-10为系统保留，第三方yum源的优先级从11-99

三、安装epel yum源

1 rpm -ivh http://mirrors.ustc.edu.cn/fedora/epel/6/i386/epel-release-6-7.noarch.rpm  2 rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-63 vi /etc/yum.repos.d/epel.repo

修改epel yum源优先级，priority=11

四、安装rpmforge yum源

1  wget http://apt.sw.be/redhat/el6/en/i386/rpmforge/RPMS/rpmforge-release-0.5.2-2.el6.rf.i686.rpm2  wget http://dag.wieers.com/rpm/packages/RPM-GPG-KEY.dag.txt3  rpm --import RPM-GPG-KEY.dag.txt4  rpm -ivh rpmforge-release-0.5.2-2.el6.rf.i686.rpm5  vi  /etc/yum.repos.d/rpmforge.repo

修改rpmforge yum源优先级，priority=12

五、安装rpmfusion yum源

也许会提示错误，多试几次。

1 sudo rpm -ivh http://download1.rpmfusion.org/free/el/updates/6/i386/rpmfusion-free-release-6-0.1.noarch.rpm

Retrieving http://download1.rpmfusion.org/free/el/updates/6/i386/rpmfusion-free-release-6-0.1.noarch.rpm

warning: /var/tmp/rpm-tmp.Gc2eET: Header V3 RSA/SHA256 Signature, key ID 849c449f: NOKEY

Preparing...                ########################################### [100%]

   1:rpmfusion-free-release ########################################### [100%]

1 sudo vim rpmfusion-free-updates.repo2 sudo vim rpmfusion-free-updates-testing.repo

修改rpmfusion yum源优先级，priority=13

六、更新yum软件包

yum check-update