Running External Commands + Seeing when they are Finished

[Tommy B]

I'm currently working on a script that I will run when I leave my
computer on at night. It runs external commands like Ad-Aware, Spybot,
AVG, Avast, and the like. The problem is, I want to know how to make it
so that one command starts only after the last one finishes. When I run
them, they end up running all at once! Can someone please tell me if
this is possible? Judging from what I've seen in Python's versitility,
I bet it can...