The first thing is to find out which version are you on. Here’s how you do it

nginx -v

It should show you something like

nginx version: nginx/1.1.19

Now that we know that we need to upgrade, the first thing to do is to backup your configuration

sudo cp /etc/nginx/nginx.conf /etc/nginx/nginx.conf.1.1.19.backup

Ok, moving on, first stop the nginx service

sudo service nginx stop

Install the dependencies

sudo aptitude install python-software-properties

Add the repository for the stable version of Nginx

sudo add-apt-repository ppa:nginx/stable

Now the usual stuff, update aptitude and upgrade it

sudo aptitude update
sudo aptitude safe-upgrade

When it asks you if you want to keep using the old config or get the new config, please select Y(es) and get the latest config. Finally, restart nginx

sudo service nginx restart

If you ask nginx what version its on, here’s what it would say

nginx -v
nginx version: nginx/1.4.7

That’s it.