檢視所有yum包
[[email protected] ~]# rpm -qa | grep yum

刪除原有yum包
[[email protected] ~]# rpm -qa|grep yum|xargs rpm -e --nodeps

共需要五個包：下載位置：http://mirrors.163.com/centos/7/os/x86_64/Packages/
  yum-plugin-fastestmirror
  yum-updateonboot
  yum-utils
  yum-metadata-parser
  yum-3.4.3-150.el7

下載需要的包
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-45.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-updateonboot-1.1.31-45.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-utils-1.1.31-45.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-3.4.3-158.el7.centos.noarch.rpm

安裝軟體包
[[email protected] ~]# rpm -ivh yum-*

  # 報錯, 依賴包的版本不符：
  rpm >= 0:4.11.3-22 is needed by yum-3.4.3-154.el7.centos.noarch
  解決方法: 將所依賴的python-urlgrabber和rpm包升級
  wget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-4.11.3-32.el7.x86_64.rpm
  wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-urlgrabber-3.10-8.el7.noarch.rpm
  # 安裝：
  rpm -Uvh rpm-4.11.3-32.el7.x86_64.rpm --nodeps
  rpm -Uvh python-urlgrabber-3.10-8.el7.noarch.rpm --nodeps

重新安裝軟體包
[[email protected] ~]# rpm -ivh yum-*
或者
[[email protected] ~]# rpm -ivh yum-plugin-fastestmirror-1.1.31-45.el7.noarch.rpm
[[email protected] ~]# rpm -ivh yum-updateonboot-1.1.31-45.el7.noarch.rpm
[[email protected] ~]# rpm -ivh yum-utils-1.1.31-45.el7.noarch.rpm
[[email protected]

更新yum源
rm /etc/yum.repos.d/redhat.repo
vim /etc/yum.repos.d/CentOS-Base.repo
# 內容:
#CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#
[base]
name=CentOS-$7 - Base - 163.com
#mirrorlist=http://mirrorlist.centos.org/?release=$7&arch=$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=$7&arch=$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=$7&arch=$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

清除yum快取
[[email protected] ~]#  yum clean all

生成快取
[[email protected] ~]#  yum makecache

更新成功， 可以安裝軟體了
[[email protected] ~]#  yum install -y vim