操作系统：Red Hat Enterprise Linux Server release 7.0 (Maipo)
虚拟工具：VM10
问题描述：该RedHat系统是一个收费的服务器操作系统，需要通过注册到红帽订阅管理。但CentOS操作系统是通过RedHat编译过来的，是免费的操作系统，Redhat可以通过使用CentOS的免费源，对于学习者来讲是非常方便的。
实战任务：Redhat7使用CentOS7的yum源
操作步骤如下：
1.查看操作系统版本
[root@sky ~]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.0 (Maipo)
2.查看系统已经安装的yum源
[root@sky ~]# rpm -qa|grep yum
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
3.卸载原有系统软件包
[root@sky ~]# rpm -e yum-utils-1.1.31-24.el7.noarch --nodeps
[root@sky ~]# rpm -e yum-langpacks-0.4.2-3.el7.noarch --nodeps
[root@sky ~]# rpm -e yum-metadata-parser-1.1.4-10.el7.x86_64 --nodeps
[root@sky ~]# rpm -e 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 --nodeps
4.保证本系统能上网
[root@sky ~]# ping www.baidu.com
PING www.a.shifen.com (61.135.169.121) 56(84) bytes of data.
64 bytes from 61.135.169.121: icmp_seq=1 ttl=128 time=40.7 ms
64 bytes from 61.135.169.121: icmp_seq=2 ttl=128 time=41.5 ms
64 bytes from 61.135.169.121: icmp_seq=3 ttl=128 time=40.3 ms
64 bytes from 61.135.169.121: icmp_seq=4 ttl=128 time=40.4 ms
5.下载CentOS7版本的软件包
[root@sky ~]# cd /usr/local/src
[root@sky src]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-kitchen-1.1.1-5.el7.noarch.rpm
[root@sky src]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-chardet-2.2.1-1.el7_1.noarch.rpm
[root@sky src]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-158.el7.centos.noarch.rpm
[root@sky src]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
[root@sky src]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-utils-1.1.31-45.el7.noarch.rpm
[root@sky src]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-updateonboot-1.1.31-45.el7.noarch.rpm
[root@sky src]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-45.el7.noarch.rpm
[root@sky src]# ls
grafana-5.3.2-1.x86_64.rpm
httpd-2.2.15-69.el6.centos.x86_64.rpm
httpd-2.4.6-80.el7.centos.x86_64.rpm
python-chardet-2.2.1-1.el7_1.noarch.rpm
python-kitchen-1.1.1-5.el7.noarch.rpm
yum-3.4.3-158.el7.centos.noarch.rpm
yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
yum-plugin-fastestmirror-1.1.31-45.el7.noarch.rpm
yum-updateonboot-1.1.31-45.el7.noarch.rpm
yum-utils-1.1.31-45.el7.noarch.rpm
6.安装软件包
[root@sky src]# rpm -ivh python-*
[root@sky src]# rpm -ivh yum-* --nodeps
7.配置repo文件
root@sky src]# cd /etc/yum.repos.d/
[root@sky yum.repos.d]# ll
总用量 0
[root@sky yum.repos.d]# wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
[root@sky yum.repos.d]# cat CentOS7-Base-163.repo
# CentOS-Base.repo
.....
[base]
name=CentOS-7 - Base - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
baseurl=http://mirrors.163.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#released updates
[updates]
name=CentOS-$releasever - Updates - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
baseurl=http://mirrors.163.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#additional packages that may be useful
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
baseurl=http://mirrors.163.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus - 163.com
baseurl=http://mirrors.163.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
#将上述$releasever改成数字7。
8.已安装完成CentOS7 yum 源
[root@sky yum.repos.d]# yum clean all
9.测试是否成功配置yum源
[root@sky yum.repos.d]# yum
[root@sky /]# yum repolist all
已加载插件：fastestmirror, product-id, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
Determining fastest mirrors
base | 3.6 kB 00:00:00
extras | 3.4 kB 00:00:00
updates | 3.4 kB 00:00:00
(1/4): base/x86_64/group_gz | 166 kB 00:00:00
(2/4): extras/x86_64/primary_db | 204 kB 00:00:00
(3/4): updates/x86_64/primary_db | 6.0 MB 00:00:07
(4/4): base/x86_64/primary_db | 5.9 MB 00:00:08
源标识 源名称 状态
base/x86_64 CentOS-7 - Base - 163.com 启用: 9,911
centosplus/x86_64 CentOS-$releasever - Plus - 163.com 禁用 #该项失败
extras/x86_64 CentOS-$releasever - Extras - 163.com 启用: 432
updates/x86_64 CentOS-$releasever - Updates - 163.com 启用: 1,614
repolist: 11,957
.........
root@sky yum.repos.d]# vi CentOS7-Base-163.repo
[centosplus]
name=CentOS-$releasever - Plus - 163.com
baseurl=http://mirrors.163.com/centos/$releasever/centosplus/$basearch/ #releasever改成数字"7"
gpgcheck=1
enabled=0 #数字“0”改成"1"
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
到此步骤，yum源才配置成功。
实战技巧：不要做#yum update，还是保持原有redhat7版本，如果一升级，则版本会更换到CentOS7。
建议升级软件包#yum upgrade