环境：RedHat 4.4
1，先安装yum
# wget http://www.parallels.com.cn/downloads/Prima/Tools/yum_forAS4.tar.gz
# tar zxvf yum_forAS4.tar.gz
# cd yum_forAS4
# rpm -ivh *.rpm
# cp CentOS-Base.repo /etc/yum.repos.d/
2，执行如下命令导入GPG Key
# rpm --import http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-4
OK,现在就可以使用yum进行升级了。