配置linux的yum镜像为阿里镜像源

1.备份当前的yum源

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

2.下载新的CentOS-Base.repo 到/etc/yum.repos.d

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

3.清空并生成缓存

yum clean all
yum makecache