環境：

redhat 7.3

1.查詢原yum

rpm -qa|grep yum

rpm -e yum-langpacks-0.4.2-7.el7.noarch --nodeps
rpm -e yum-3.4.3-150.el7.noarch --nodeps
rpm -e yum-rhn-plugin-2.0.1-6.el7.noarch --nodeps
rpm -e yum-utils-1.1.31-40.el7.noarch --nodeps
rpm -e yum-metadata-parser-1.1.4-10.el7.x86_64 --nodeps

3.映象庫下載下列軟體

wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-updateonboot-1.1.31-42.el7.noarch.rpm  
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-utils-1.1.31-42.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.2.29-81.el6.centos.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-42.el7.noarch.rpm 
 

4.安裝yum

rpm -ivh --nodeps yum-updateonboot-1.1.31-42.el7.noarch.rpm  
rpm -ivh --nodeps yum-utils-1.1.31-42.el7.noarch.rpm
rpm -ivh --nodeps yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
rpm -ivh --nodeps yum-3.2.29-81.el6.centos.noarch.rpm
rpm -ivh --nodeps yum-plugin-fastestmirror-1.1.31-42.el7.noarch.rpm 
 

5.配置yum倉庫

cd /etc/yum.repos.d/ #yum倉庫配置檔案路徑
vi CentOS-Base.repo #編寫yum倉庫配置
內容：
[base]
name=CentOS-$releasever -Base
baseurl=http://mirrors.163.com/centos/7/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/7/os/x86_64/RPM-GPG-KEY-CentOS-7

#released updates
[updates]
name=CentOS-$releasever - Updates
baseurl=http://mirrors.163.com/centos/7/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/7/os/x86_64/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-$releasever - Extras
baseurl=http://mirrors.163.com/centos/7/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/7/os/x86_64/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
baseurl=http://mirrors.163.com/centos/7/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.163.com/centos/7/os/x86_64/RPM-GPG-KEY-CentOS-7
 

6.更新yum

yum clean all