Keeping track of installed packages in Ubuntu

I find out, a while ago, an hyper simple trick to get the list of installed packages on your Ubuntu PC.  This trick works for Ubuntu and all it's derivative (Kubuntu, Xubuntu, etc.)

To output all the package list to a text file, enter the following command in a terminal window :

dpkg --get-selections > installed-software.txt

Then, keep this file in a safe place (an usb flash drive is a good candidate). 

Whenever you need to reinstall all your preferred Ubuntu packages automatically (in case you upgrade your computer or replace an hard drive), you could simply do the following (using the text file previously saved):

dpkg --set-selections < installed-software.txt dselect

After a while, all your preferred applications will be reinstalled and you will be ready to go!

NOTICE: This technique won't replace a full backup of your data.