nginx之yum源
官方网站：http://nginx.org/en/linux_packages.html#RHEL-CentOS
cat > /etc/yum.repos.d/nginx.repo << EOF [nginx-stable] name=nginx stable repo baseurl=http://nginx.org/packages/centos/\$releasever/\$basearch/ gpgcheck=1 enabled=1 gpgkey=https://nginx.org/keys/nginx_signing.key EOF