centos操作系统运行yum命令是出现如下报错：
解决办法：
由于CentOS的源地址内容已移除，CentOS 操作系统结束了生命周期，源地址内容已移除。
只需要将它的base源换成其他可用源，我这里将它换成了阿里的base源
备份原来的源：
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup执行如下命令安装新的源：
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo重新执行yum相关命令，就可以正常使用了。
若显示wget命令不存在
需手动替换CentOS-Base.repo这个文件，替换成如下内容，建议直接复制粘贴替换原文件的内容，cat写入可能不生效：
# 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-$releasever - Base - mirrors.aliyun.comfailovermethod=prioritybaseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/ http://mirrors.aliyuncs.com/centos/$releasever/os/$basearch/ http://mirrors.cloud.aliyuncs.com/centos/$releasever/os/$basearch/gpgcheck=1gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7 #released updates [updates]name=CentOS-$releasever - Updates - mirrors.aliyun.comfailovermethod=prioritybaseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/ http://mirrors.aliyuncs.com/centos/$releasever/updates/$basearch/ http://mirrors.cloud.aliyuncs.com/centos/$releasever/updates/$basearch/gpgcheck=1gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7 #additional packages that may be useful[extras]name=CentOS-$releasever - Extras - mirrors.aliyun.comfailovermethod=prioritybaseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/ http://mirrors.aliyuncs.com/centos/$releasever/extras/$basearch/ http://mirrors.cloud.aliyuncs.com/centos/$releasever/extras/$basearch/gpgcheck=1gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7 #additional packages that extend functionality of existing packages[centosplus]name=CentOS-$releasever - Plus - mirrors.aliyun.comfailovermethod=prioritybaseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/ http://mirrors.aliyuncs.com/centos/$releasever/centosplus/$basearch/ http://mirrors.cloud.aliyuncs.com/centos/$releasever/centosplus/$basearch/gpgcheck=1enabled=0gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7 #contrib - packages by Centos Users[contrib]name=CentOS-$releasever - Contrib - mirrors.aliyun.comfailovermethod=prioritybaseurl=http://mirrors.aliyun.com/centos/$releasever/contrib/$basearch/ http://mirrors.aliyuncs.com/centos/$releasever/contrib/$basearch/ http://mirrors.cloud.aliyuncs.com/centos/$releasever/contrib/$basearch/gpgcheck=1enabled=0gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7最后执行如下命令完成：
yum clean allyum makecacahe删除其他库
若还是无法运行yum ,查看base是否存在任何本地存储库或任何其他媒体存储库，若有其它的先删除其他的，命令：
ll /etc/yum.repos.d
删除CentOS7-Base-163.repo这个base源:
rm -rf /etc/yum.repos.d/CentOS7-Base-163.repo再次运行如下命令：
yum clean allyum makecacahe希望对你有帮助，若遇到其他情况请留言，我看到了会第一时间回复。