backup list of installed packages

Question

I want to reinstall my linux system (specifically linux mint). I have kept important data elsewhere, so I can safely remove everything.

However, I want to do the following:

1. save the list of packages I have installed so far
2. after reinstall take the backup list and use it to install packages

Are there tools that can assist in doing this. I know I can use dpkg -l to get list but perhaps I only want the leafs - packages that no other depend on.

Answer 1

You can save you current list with

dpkg --get-selections > sel.list

and copy this file in safe place to be able copy it on a new machine. (and also you should backup your settings from /etc/ dir if you did some changes there)

To restore it with you should run:

sudo dpkg --set-selections < sel.list
sudo apt-get update && sudo apt-get -u dselect-upgrade

Answer 2

The problem with using dpkg --get-selections is that it does not preserve some package states such as "automatically installed". To preserve all data, you can use the aptitude front-end to backup and restore the package list:

aptitude search -F '%100p' '~i!~M' > package_list #backup

xargs aptitude --schedule-only install < package_list
aptitude install #restore