阿里yum源

1. ‌备份原源‌：mkdir -p /etc/yum.repos.d/backup && mv /etc/yum.repos.d/*.repo /etc/yum.repos.d/backup/
2. ‌下载阿里源配置‌：curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
3. ‌清理并重建缓存‌：yum clean all && yum makecache
4. ‌（可选）配置 EPEL 扩展源‌：curl -o /etc/yum.repos.d/epel.repo https://mirrors.aliyun.com/repo/epel-7.repo