下载安装yum：

wget http://yum.baseurl.org/download/3.2/yum-3.2.28.tar.gz

tar xvf yum-3.2..tar.gz

cd yum-3.2.

touch /etc/yum.conf

cp etc/yum.conf /etc/yum.conf

yummain.py install yum

yum check-update

yum update

yum clean all

当使用CentOS源安装软件出现如下错误的解决办法：

PackageKit-0.5.-.el6.x86_64 has missing requires of PackageKit-yum = ('', '0.5.8', '19.el6')

PackageKit-0.5.-.el6.x86_64 has missing requires of PackageKit-yum-plugin = ('', '0.5.8', '19.el6')

运行下面命令

yum remove 'rhn-check-1.0.0.1-16.el6.noarch'

yum instal PackageKit-glib

yum install abrt-addon-ccpp

yum install PackageKit-yum

yum install PackageKit-yum-plugin