Remove terminated/unused docker containers from your system

Problem

After playing around with docker containers for some time the terminated/unused ones are still hanging around your system, and prevent you from using a new container with the same name as any of the previous ones with the error:

Solution

You can remove all the containers by using the following:

Combining multiple ps pages into a multiple page pdf file

Problem
You have a lot of ps files and you want to combine them into a single pdf file with multiple pages.

Solution
You can use Ghostscript: