更换centos7源

yum install wget -y

cd /etc/yum.repos.d && for r in *.repo; do mv $r $r.bak;done

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

修改CentOS-Base.repo文件中的$releasever全部替换为版本号 7

yum clean all

yum makecache

yum update -y