阿里云yum源配置

# 切换aliyun
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
cd /etc/yum.repos.d/
# centos6.x
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo

# centos7.x
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

yum clean all
yum makecache
yum install tree -y
yum update -y