debian package backup

You might prefer to have a clean system on reinstall but sometimes it is nice to reinstall applications from a previous machine/setup. Keeping a backup list of packages will make this a snap. Just give your package manager a list of all the packages you want it to install and let it rip.

Here are the backup and restore methods for each of the major distros/package managers. Backup

dpkg –get-selections > installed-software.log

Restore

dpkg –set-selections deselect install

Source: http://www.nixtutor.com/linux/keep-a-backup-of-installed-packages/