由於redhat自帶的yum須註冊方可使用，於是我們安裝centos7.0的yum用以代替

一、檢視系統版本：cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.0 (Maipo)

二、刪除系統自帶yum
rpm -qa | grep yum | xargs rpm -e –nodeps

三、下載相關安裝包RPM（http://mirrors.163.com/centos/7/os/x86_64/Packages/）
1、python-iniparse-0.4-9.el7.noarch.rpm
2、 python-urlgrabber-3.10-8.el7.noarch.rpm
3、yum-plugin-fastestmirror-1.1.31-40.el7.noarch.rpm
4、yum-updateonboot-1.1.31-40.el7.noarch.rpm
5、yum-3.4.3-150.el7.centos.noarch.rpm
6、yum-utils-1.1.31-40.el7.noarch.rpm
7、yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
由於更新，根據相應版本自己選擇

之後安裝，注意要如此：rpm -ivh yum-* python-*
隨著版本升級，可能安裝yum可能還會依賴其他的python-*，

注意：上面幾步是坑

我開始以為在官網中下載最新版安裝包然後根據需要下載相應的依賴檔案即可，誰知下了yum-3.4.3-150.el7.centos.noarch.rpm 這個最新版之後，依賴好多檔案，然後我就一個個下，結果最後安裝時還是生成不了yum，簡直無語。。

後來我下了yum-3.4.3-132.el7.centos.0.1.noarch.rpm，依賴
1、python-iniparse-0.4-9.el7.noarch.rpm
2、yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
3、yum-plugin-fastestmirror-1.1.31-40.el7.noarch.rpm

之後rpm -ivh yum-* 即可生成yum

[[email protected] yum.repos.d]# rpm -aq|grep yum
yum-plugin-fastestmirror-1.1.31-40.el7.noarch
yum-metadata-parser-1.1.4-10.el7.x86_64
yum-3.4.3-132.el7.centos.0.1.noarch

四、將centOS中的repo匯入redhat中的/etc/yum.repos.d中（注意：只有yum安裝好後，etc下才會有yum.repos.d資料夾）
http://mirrors.163.com/.help/centos.html

開啟上面網址，下載CentOS-Base-163.repo，將其放到/etc/yum.repos.d目錄下，並
vim /etc/yum.repos.d/CentOS-Base-163.repo，進行修改如下所示：

[base]
name=CentOS-7 - Base

[updates]
name=CentOS-7- Updates

[extras]
name=CentOS-7 - Extras

[centosplus]
name=CentOS-7 - Plus

五、 yum clean all 清除原有快取

[[email protected] yum.repos.d]# yum clean all
Loaded plugins: fastestmirror, product-id, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
Cleaning repos: base epel extras updates
Cleaning up everything

六、yum makecache 獲取yum列表

[[email protected] yum.repos.d]# yum makecache
Loaded plugins: fastestmirror, product-id, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
base | 3.6 kB 00:00:00
epel/x86_64/metalink | 5.7 kB 00:00:00
epel | 4.4 kB 00:00:00
extras | 3.4 kB 00:00:00
updates | 3.4 kB 00:00:00
(1/16): base/x86_64/other_db | 2.1 MB 00:00:04
(2/16): base/x86_64/primary_db | 4.9 MB 00:00:04
epel/x86_64/primary_db FAILED ] 2.1 MB/s | 12 MB 00:00:15 ETA
http://ftp6.sjtu.edu.cn/fedora/epel/7/x86_64/repodata/abd574868d90db0a564394f31fe3b35368870700fca013beff3d8fe9a0b84b64-primary.sqlite.bz2: [Errno 14] curl#7 - “Failed to connect to 2001:da8:8000:6023::230: Network is unreachable”
Trying other mirror.
(3/16): base/x86_64/filelists_db | 5.8 MB 00:00:05
(4/16): extras/x86_64/filelists_db | 92 kB 00:00:00
(5/16): epel/x86_64/group_gz | 250 kB 00:00:05
(6/16): extras/x86_64/prestodelta | 1.7 kB 00:00:00
(7/16): extras/x86_64/other_db | 67 kB 00:00:00
(8/16): extras/x86_64/primary_db | 35 kB 00:00:00
(9/16): updates/x86_64/prestodelta | 184 kB 00:00:00
(10/16): base/x86_64/group_gz | 157 kB 00:00:06
(11/16): epel/x86_64/filelists_db | 4.9 MB 00:00:01
(12/16): epel/x86_64/other_db | 1.7 MB 00:00:01
(13/16): epel/x86_64/primary_db | 3.5 MB 00:00:01
(14/16): updates/x86_64/filelists_db | 2.7 MB 00:00:02
(15/16): updates/x86_64/primary_db | 4.7 MB 00:00:03
(16/16): updates/x86_64/other_db | 14 MB 00:01:56
(1/2): epel/x86_64/updateinfo | 129 kB 00:00:00
(2/2): epel/x86_64/pkgtags | 1.3 MB 00:00:00
Determining fastest mirrors
* base: mirrors.yun-idc.com
* epel: mirrors.yun-idc.com
* extras: mirrors.yun-idc.com
* updates: mirrors.yun-idc.com
Metadata Cache Created

到此yum就可以線上安裝軟體了。