Ever forget what you had installed and find yourself at a fresh ubuntu install thinking to yourself... Damn now I gotta open up synaptic and search for everything I had... Well fortunately you dont need to do that. With this easy howto you can also restore all your packages that were installed by simply creating a package list and uninstalling every application installed after the list was made.
Lets get started shall we?
The following command creates a list of all the installed packages at the present time:
sudo dpkg --get-selections > /etc/package.selections
Now we created our package list and we can copy this list to a new ubuntu computer and install the same packages in the list to the new machine or, restore the packages to the time you created the package list:
sudo dpkg --set-selections < /etc/package.selections && apt-get dselect-upgrade
The above command will uninstall all packages installed after you created your restore list.