How to find out in a shellscript if upgrades are available after an apt-get update

Question

I have a script that executes apt-get update on several servers and I have to find out whether there are upgrades available or not in order to schedule apt-get upgrades etc...

Looking at the docs I don't see how I could do this task.

Answer 1

You can use apt-get -s dist-upgrade and parse it's output. -s means simulation: no real actions will be done

Answer 2

On one of my Ubuntu servers I use a program called unattended-upgrades. It sends me an email every night with a list of available updates.