红帽系统更换yum源
因为红帽系统 默认自带的 yum 源需要注册，才能更新,而我们想不花钱也可以更新，那只能替换掉RedHat的yum源了，下面就给大家介绍一下如果更换RedHat的yum源。
第一步：检查是否安装yum软件包。
首先，可以用rpm -qa |grep yum 命令来查看RHEL是否安装了yum，如果安装了，就会显示系统安装的那些yum包：
rpm -qa | grep yum
#输出：
yum-utils-1.1.31-24.el7.noarch
yum-langpacks-0.4.2-3.el7.noarch
yum-metadata-parser-1.1.4-10.el7.x86_64
yum-rhn-plugin-2.0.1-4.el7.noarch
PackageKit-yum-0.8.9-11.el7.x86_64
yum-3.4.3-118.el7.noarch
第二步： 卸载redhat自带的yum软件包
rpm -e yum-3.4.3-118.el7.noarch --nodeps
#把第一步输出的东西全卸载了
rpm -e xxx.noarch --odeps
卸载完成后，再用命令 rpm -qa |grep yum 查看是否已经卸载完成，如果输入命令后，无信息显示表示已经卸载完成
第三步.下载新的yum软件包
找到自己所需要的版本下载：
[root@Linuxprobe ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-118.el7.centos.noarch.rpm
--2016-01-17 20:43:15-- http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-118.el7.centos.noarch.rpm
Resolving mirrors.163.com (mirrors.163.com)... 123.58.173.185, 123.58.173.186
Connecting to mirrors.163.com (mirrors.163.com)|123.58.173.185|:80... connected.
HTTP request sent, awaiting response... 404 Not Found
2016-01-17 20:43:15 ERROR 404: Not Found. //如果找不到，是安装包更新了，你可以到这个网站http://mirrors.163.com/centos/7/os/x86_64/Packages/复制下载链接，然后再下载下来；
root@linuxprobe ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-132.el7.centos.0.1.noarch.rpm
[root@linuxprobe ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
[root@linuxprobe ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-utils-1.1.31-34.el7.noarch.rpm
[root@linuxprobe ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-updateonboot-1.1.31-34.el7.noarch.rpm
[root@linuxprobe ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-34.el7.noarch.rpm
第四步、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
rpm -ivh yum-*
第五步、新建repo 配置文件。
vim /etc/yum.repos.d/CentOS-Base.repo
#写入一下内容
#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-$7 - Base - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$7&arch=$basearch&repo=os
baseurl=http://mirrors.163.com/centos/7/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#released updates
[updates]
name=CentOS-$7 - Updates - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$7&arch=$basearch&repo=updates
baseurl=http://mirrors.163.com/centos/7/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#additional packages that may be useful
[extras]
name=CentOS-$7 - Extras - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$7&arch=$basearch&repo=extras
baseurl=http://mirrors.163.com/centos/7/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$7 - Plus - 163.com
baseurl=http://mirrors.163.com/centos/7/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
第六步：运行yum makecache命令生成缓存。
yum clean all
yum makecache
yum update
经过上述六个步骤，新的yum源已经安装完成了，我们可以用yum install 命令来测试安装是否正常：