新安装了redhat6.5.安装后，登录系统，使用yum update 更新系统。提示：
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
无法更新。
redhat 默认自带的 yum 源需要注册，才能更新。我们想不花钱也可以更新，需要替换掉redhat的yum源。
1.检查是否安装yum包
查看RHEL是否安装了yum，若是安装了，那么又有哪些yum包：
[root@test ~]# rpm -qa |grep yum yum-plugin-security-1.1.30-14.el6.noarch yum-3.2.29-40.el6.noarch yum-utils-1.1.30-14.el6.noarch yum-metadata-parser-1.1.2-16.el6.x86_64 yum-rhn-plugin-0.9.1-48.el6.noarch
2. 删除redhat自带的yum包
卸载上面显示的所有yum包：
[root@test ~]# rpm -qa|grep yum|xargs rpm -e --nodeps [root@test ~]# rpm -qa |grep yum
[root@test ~]#
查看，无信息显示表示已经卸载完成。
3.下载新的yum包。使用Centos6.5的yum包
[root@test yum.repos.d]# wget http://centos.ustc.edu.cn/centos/6/os/x86_64/Packages/yum-3.2.29-69.el6.centos.noarch.rpm [root@test yum.repos.d]# wget http://centos.ustc.edu.cn/centos/6/os/x86_64/Packages/yum-metadata-parser-1.1.2-16.el6.x86_64.rpm [root@test yum.repos.d]# wget http://centos.ustc.edu.cn/centos/6/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.30-30.el6.noarch.rpm [root@test yum.repos.d]# ls rhel-source.repo rhel-source.repo.bak yum-3.2.29-69.el6.centos.noarch.rpm yum-metadata-parser-1.1.2-16.el6.x86_64.rpm yum-plugin-fastestmirror-1.1.30-30.el6.noarch.rpm
安装yum软件包
注意:单个的安装包可能会依赖其它包（例如yum和yum-fastestmirror会相互依赖），所以我们可以把所有这些包放在一起，用一行命令将它们同时安装即可：
[root@test yum.repos.d]# rpm -ivh yum-metadata-parser-1.1.2-16.el6.x86_64.rpm yum-3.2.29-69.el6.centos.noarch.rpm yum-plugin-fastestmirror-1.1.30-30.el6.noarch.rpm warning: yum-metadata-parser-1.1.2-16.el6.x86_64.rpm: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEY Preparing... ########################################### [100%] 1:yum-metadata-parser ########################################### [ 33%] 2:yum-plugin-fastestmirro########################################### [ 67%] 3:yum ########################################### [100%]
4.更换yum源。使用中科大的源
# cd /etc/yum.repos.d/ # wget http://mirrors.ustc.edu.cn/.help/CentOS6-Base.repo # vi CentOS6-Base.repo
编辑文件，把文件里面的$releasever全部替换为版本号，即6.5 最后保存！
[root@test yum.repos.d]# vim CentOS-Base.repo [root@test yum.repos.d]# sed -i 's#$releasever#6.5#g' CentOS-Base.repo [root@test yum.repos.d]# vim CentOS-Base.repo #CentOS-Base.repo # # The mirror system uses the connecting IP address of the client and the # update status of each mirror to pick mirrors that are updated to and # geographically close to the client. You should use this for CentOS updates # unless you are manually picking other mirrors. # # If the mirrorlist= does not work for you, as a fall back you can try the # remarked out baseurl= line instead. # # # [base] name=CentOS-6.5 - Base - mirrors.ustc.edu.cn baseurl=http://mirrors.ustc.edu.cn/centos/6.5/os/$basearch/ # #mirrorlist=http://mirrorlist.centos.org/?release=6.5&arch=$basearch&repo=os gpgcheck=1 gpgkey=http://mirrors.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-6 #released updates [updates] name=CentOS-6.5 - Updates - mirrors.ustc.edu.cn baseurl=http://mirrors.ustc.edu.cn/centos/6.5/updates/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=6.5&arch=$basearch&repo=updates gpgcheck=1 gpgkey=http://mirrors.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-6 #additional packages that may be useful [extras] name=CentOS-6.5 - Extras - mirrors.ustc.edu.cn baseurl=http://mirrors.ustc.edu.cn/centos/6.5/extras/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=6.5&arch=$basearch&repo=extras gpgcheck=1 gpgkey=http://mirrors.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-6 #additional packages that extend functionality of existing packages [centosplus] name=CentOS-6.5 - Plus - mirrors.ustc.edu.cn baseurl=http://mirrors.ustc.edu.cn/centos/6.5/centosplus/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=6.5&arch=$basearch&repo=centosplus gpgcheck=1 enabled=0 gpgkey=http://mirrors.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-6 #contrib - packages by Centos Users [contrib] name=CentOS-6.5 - Contrib - mirrors.ustc.edu.cn baseurl=http://mirrors.ustc.edu.cn/centos/6.5/contrib/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=6.5&arch=$basearch&repo=contrib gpgcheck=1 enabled=0 gpgkey=http://mirrors.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-6
5.清除原有缓存
# yum clean all
重建缓存，以提高搜索安装软件的速度
# yum makecache
6.更新系统
# yum update
163更新源：http://mirrors.163.com/
中科大更新源：http://mirrors.ustc.edu.cn/