解决setlocale: LC_CTYPE: cannot change locale (UTF-8): No such file or directory
vim /etc/environment

add these lines…

LANG=en_US.utf-8
LC_ALL=en_US.utf-8

修改DNS服务器：/etc/sysconfig/network-scripts/ifcfg-eth0
DNS1=8.8.8.8
DNS2=8.8.4.4

修改主机名：hostnamectl set-hostname

yum -y install epel-release

重新安装yum源：
rm -rf /etc/yum.repos.d/* && wget http://mirror.centos.org/centos/7/os/x86_64/Packages/centos-release-7-9.2009.0.el7.centos.x86_64.rpm && rpm --replacefiles --replacepkgs -ivh centos-release-7-9.2009.0.el7.centos.x86_64.rpm && yum clean all && yum repolist

yum groupinstall “Development Tools”