curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

二选一

查看配置仓库地址

vi /etc/yum.repos.d/CentOS-Base.repo

sudo yum clean all sudo yum makecache