Do you want to upgrade your current Nginx version and upgrade to latest nginx version on your Ubuntu server?

First, check your nginx version :

nginx -v

On Ubuntu it shows like this:

nginx version: nginx/1.4.6 (Ubuntu)

Then add Nginx PPA

sudo add-apt-repository ppa:nginx/stable

After that we need to update our Ubuntu aptitude

sudo apt-get update

Then rerun install nginx to upgrade it:

sudo apt-get install nginx