centos7 添加yum源

进入yum.repos.d文件夹
cd /etc/yum.repos.d/
mv CentOS-Base.repo CentOS-Base.repo.backup

下载yum源
wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
wget http://mirrors.aliyun.com/repo/Centos-7.repo

yum clean all 清除系统yum 缓存
yum makecache 生成yum缓存

如果yum报错 进程被占用
rm -f /var/run/yum.pid