Get a list of whats installed on your linux box

I run Ubuntu on my laptop. Every so often it is better to start over by reinstalling from scratch. I needed an easy way to keep track of what I had installed. This way when I set up the new system I can just go through the list, line by line and reinstall what ever I need to. This is not a perfect method as it includes a lot of system apps too but its better then nothing. As a result I tend to also make a hand written inventory to be safe. Here is the command you can run to create a text file of your installed packages. 

dpkg –get-selections > installed-packages