安装nginx
wget http://nginx.org/keys/nginx_signing.key
apt-key add nginx_signing.key

add this to /etc/apt/source.list

deb http://nginx.org/packages/mainline/ubuntu/ codename nginx
deb-src http://nginx.org/packages/mainline/ubuntu/ codename nginx
version codename
12.04 precise
14.04 trusty
15.10 wily
16.04 xenial

then

apt-get update
apt-get install nginx