In case you needed for various reasons to reinstall your Debian / Ubuntu, and you want the exact same packages without too much shaking, there are some simple steps to follow:

Save on a support package list and the sources.list:

dpkg --get-selections | grep -v deinstall > ~/lista-pacchetti

cp /etc/apt/sources.list ~/sources.list.bkp

Then reinstall your distribution and update:

sudo apt-get update

sudo apt-get dist-upgrade

then reinstall the packages previously saved:

sudo dpkg --set-selections < ~/lista-pacchetti

apt-get install dselect

dselect install