reinstalling system and packages

[Roy Strachan]

Hi,
>
> I need to reinstall ubuntu 10.04 LTS on my machine. But I'd like to
> record what ubuntu packages are installed so that I can later on
> reinstall these packages easily. I'm wondering if there is a command
> to keep track of all the additional packages installed. It is better
> that this information is dumped into a file so that it can be read
> some other command to easily reinstall all these packages. Is there
> such commands for saving the packages info and reinstall the packages?
>
> --
> Regards,
> Peng
>


This works:

http://www.arsgeek.com/2006/09/19/ubuntu-tricks-how-to-generate-a-list-of-installed-packages-and-use-it-to-reinstall-packages>