一：删除原有的yum

1.查看已经安装的yum

[root@Server-i-09nwynqbbd ~]# rpm -qa |grep yum

yum-3.4.3-161.el7.centos.noarch

yum-utils-1.1.31-54.el7_8.noarch

yum-plugin-fastestmirror-1.1.31-50.el7.noarch

yum-metadata-parser-1.1.4-10.el7.x86_64

2.删除yum包

[root@Server-i-09nwynqbbd ~]# rpm -qa|grep yum|xargs rpm -e --nodeps

3.查看是否删除完毕（未找到yum包则删除完成）

[root@Server-i-09nwynqbbd ~]# rpm -qa |grep yum

[root@Server-i-09nwynqbbd ~]# 

二：查看Liunx系统版本

[root@Server-i-09nwynqbbd ~]# uname -an

Linux Server-i-09nwynqbbd 3.10.0-957.el7.x86_64 #1 SMP Thu Nov 8 23:39:32 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

[root@Server-i-09nwynqbbd ~]# cat /etc/redhat-release 

CentOS Linux release 7.6.1810 (Core)

三：下载yum有关的RPM包

[root@Server-i-09nwynqbbd ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-iniparse-0.4-9.el7.noarch.rpm

[root@Server-i-09nwynqbbd ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-168.el7.centos.noarch.rpm

[root@Server-i-09nwynqbbd ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-utils-1.1.31-54.el7_8.noarch.rpm

[root@Server-i-09nwynqbbd ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-54.el7_8.noarch.rpm

[root@Server-i-09nwynqbbd ~]# wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm

四：安装下载好的yum有关的RPM包

[root@Server-i-09nwynqbbd ~]# rpm -ivh python-iniparse-0.4-9.el7.noarch.rpm --force --nodeps

[root@Server-i-09nwynqbbd ~]# rpm -ivh yum-* --force --nodeps

[root@Server-i-09nwynqbbd ~]# rpm -qa |grep yum

yum-3.4.3-168.el7.centos.noarch

yum-plugin-fastestmirror-1.1.31-54.el7_8.noarch

yum-utils-1.1.31-54.el7_8.noarch

yum-metadata-parser-1.1.4-10.el7.x86_64

五：查看是否安装完成

[root@Server-i-09nwynqbbd ~]# yum makecache

已加载插件：fastestmirror, product-id, search-disabled-repos, subscription-manager



This system is not registered with an entitlement server. You can use subscription-manager to register.



Loading mirror speeds from cached hostfile base                  | 3.6 kB  00:00:00     

docker-ce-stable                                                 | 3.5 kB  00:00:00     

epel                                                             | 4.7 kB  00:00:00     

extras                                                           | 2.9 kB  00:00:00     

updates                                                          | 2.9 kB  00:00:00     

(1/9): epel/x86_64/prestodelta                                   | 1.5 kB  00:00:00     

(2/9): docker-ce-stable/7/x86_64/filelists_db                    |  29 kB  00:00:00     

(3/9): docker-ce-stable/7/x86_64/other_db                        | 121 kB  00:00:00     

(4/9): extras/7/x86_64/filelists_db                              | 259 kB  00:00:00     

(5/9): extras/7/x86_64/other_db                                  | 145 kB  00:00:00     

(6/9): updates/7/x86_64/other_db                                 | 829 kB  00:00:00     

(7/9): epel/x86_64/other_db                                      | 3.4 MB  00:00:00     

(8/9): updates/7/x86_64/filelists_db                             | 6.6 MB  00:00:01     

(9/9): epel/x86_64/filelists_db                                  |  12 MB  00:00:02     

元数据缓存已建立

[root@Server-i-09nwynqbbd ~]#