Apt Backup Question

[Markus Kolb]

rodrigo ahumada wrote on Sun, Jan 02, 2005 at 18:43:56 -0300:
> 
> 
> >From: Simon Taplin <simon.taplin at gmail.com>
> >Reply-To: simon.taplin at gmail.com
> >To: Ubuntu Users <ubuntu-users at lists.ubuntu.com>
> >Subject: Apt Backup Question
> >Date: Sun, 02 Jan 2005 18:19:14 +0200
> >
> >I'm backing up my apt cache and list of files in the apt repositories for 
> >if I need to reformat my machine or install more machines. By backing up 
> >the list of files in the repositories, is apt smart enough to figure out 
> >that security updates have not been installed on the new machine even 
> >through they had been installed on the old machine?
> >
> you mean that you install an older version but then copy new .deb packages 
> to /var/cache/apt/archives and then run "apt-get upgrade" and apt doesn't 
> download anything from network?
> 
> i did that, but before upgrade i run update to make the database up to 
> date, only then apt look the cache to see if the packages are already 
> downloaded...

By "update" Rodrigo means apt-get update, I think ...

The list of packages installed or de-installed can be saved with 
dpkg --get-selections '*' > textfile.txt
You should backup this listfile, too.

For a reinstall of the OS you can then simply put in the backuped
package cache in the right place,
use cat textfile.txt | dpkg --set-selections to mark the right packages
for installation and then run
apt-get update
apt-get upgrade

Other things to backup could be the debconf package settings and at
least parts of the /etc directory.

Markus