备份CentOS-Base.repo

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

进入配置文件文件夹

cd /etc/yum.repos.d/

下载配置文件

163：

wget http://mirrors.163.com/.help/CentOS6-Base-163.repo

aliyun

centos5：

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo

centos6:

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo

centos7:

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

清理

yum clean all

更新缓存

yum makecache
yum install tree -y
yum update -y