Applying updates

[J.B. Nicholson-Owens]

Martin Pitt wrote:
> Just put
> 
> deb http://security.ubuntu.com/ubuntu/ warty-security main restricted
> 
> into your /etc/apt/sources.list

What are we getting with this that we wouldn't get if we did not modify 
/etc/apt/sources.list at all?

It was my (misunderstanding, apparently) that all we had to do is

    sudo apt-get update && sudo apt-get upgrade

in a terminal window from time to time and we'd pick up all available updates 
to all the packages we had installed, regardless of why the packages were updated.