1、當前系統環境：

2、更換yum源：

1) 解除安裝本地yum:

# rpm -qa|grep yum    　　#檢視本地yum

# rpm -qa|grep yum|xargs rpm -e --nodeps     　　#解除安裝本地yum，不檢查依賴性，解除安裝yum程式

2) 下載CentOS yum程式

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-161.el7.centos.noarch.rpm     

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-50.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     

使用wget命令下載，也可以用瀏覽器下載。rpm包下載地址http://mirrors.163.com/centos/7/os/x86_64/Packages/ ，包的版本會有更新，選擇最新版本下載

安裝CentOS yum程式

為避免他們之間互相依賴，三個程式一起安裝

# rpm -ivh yum-3.4.3-161.el7.centos.noarch.rpm yum-plugin-fastestmirror-1.1.31-50.el7.noarch.rpm yum-metadata-parser-1.1.4-10.el7.x86_64.rpm   

安裝報錯，依賴軟體版本不相容，

警告：yum-3.4.3-161.el7.centos.noarch.rpm: 頭V3 RSA/SHA256 Signature, 金鑰 ID f4a80eb5: NOKEY   
錯誤：依賴檢測失敗：                                                                                                                                   
python-urlgrabber >= 3.10-8 被 yum-3.4.3-161.el7.centos.noarch 需要                                                         
rpm >= 0:4.11.3-22 被 yum-3.4.3-161.el7.centos.noarch 需要                                                                       

重新下載新版本的依賴軟體，安裝更新

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-4.11.3-35.el7.x86_64.rpm   

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-libs-4.11.3-35.el7.x86_64.rpm   

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-build-libs-4.11.3-35.el7.x86_64.rpm   

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-python-4.11.3-35.el7.x86_64.rpm   

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/python-chardet-2.2.1-1.el7_1.noarch.rpm   

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/python-kitchen-1.1.1-5.el7.noarch.rpm   

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/python-urlgrabber-3.10-9.el7.noarch.rpm   

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/libxml2-python-2.9.1-6.el7_2.3.x86_64.rpm   

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-4.11.3-35.el7.x86_64.rpm   

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-sign-4.11.3-35.el7.x86_64.rpm     

#  wget  http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-build-4.11.3-35.el7.x86_64.rpm     

更新依賴軟體：

# rpm –ivh python-* 

# rpm -ivh libxml*   

# rpm –Uvh rpm*   

再次安裝yum程式

# rpm -ivh yum-3.4.3-161.el7.centos.noarch.rpm yum-plugin-fastestmirror-1.1.31-50.el7.noarch.rpm yum-metadata-parser-1.1.4-10.el7.x86_64.rpm     

安裝報錯：

錯誤：依賴檢測失敗：                                                                                   
python-urlgrabber >= 3.10-8 被 yum-3.4.3-161.el7.centos.noarch 需要       

Python-urlgrabber版本不相容，下載對應的版本。

#  wget  ftp://ftp.icm.edu.pl/vol/rzm3/linux-centos-altarch/7.5.1804/os/armhfp/Packages/python-urlgrabber-3.10-8.el7.noarch.rpm     

安裝：

# rpm -ivh python-urlgrabber-3.10-8.el7.noarch.rpm   

再次安裝yum程式

# rpm -ivh yum-3.4.3-161.el7.centos.noarch.rpm yum-plugin-fastestmirror-1.1.31-50.el7.noarch.rpm yum-metadata-parser-1.1.4-10.el7.x86_64.rpm   

安裝成功。

3) repo 配置檔案

下載配置檔案

#  cd /etc/yum.repos.d/　　#進入到yum配置檔案目錄

#  wget http://mirrors.163.com/.help/CentOS7-Base-163.repo    #下載配置檔案

設定配置檔案

# sed -i "s;\$releasever;7;g" CentOS7-Base-163.repo   

替換新的repo檔案

# mv redhat.repo redhat.repo.bak   

配置檔案內容如下：

[base]
name=CentOS-7 - Base - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$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=$releasever&arch=$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=$releasever&arch=$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

更新yum快取

# yum clean all　　#清除yum快取

# yum makecache  　　#更新yum快取

執行yumrepolist檢視，如果顯示出repo倉庫列表，並顯示軟體包數量則OK。

#  yum  repolist   

至此yum源更換完成。