nginx官方文档说明：http://nginx.org/en/linux_packages.html#RHEL-CentOS
1.添加源
cd /etc/yum.repos.d/ vim nginx.repo #插入下面的内容 [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 [nginx-mainline] name=nginx mainline repo baseurl=http://nginx.org/packages/mainline/centos/$releasever/$basearch/ gpgcheck=1 enabled=0 gpgkey=https://nginx.org/keys/nginx_signing.key