[PLUG] Reinstall, yet save everything

[John Jason Jordan]

On Fri, 23 Oct 2009 21:58:41 -0700
Eric Wilhelm <enobacon at gmail.com> dijo:

> # from John Jason Jordan
> # on Friday 23 October 2009 20:29:
> 
> >I could use
> >information about how to get a list (printout) of all installed
> >applications.

> If you installed them with aptitude, `dpkg -l | grep '^i'` or perhaps 
> `dpkg --get-selections` possibly informed by the dpkg manpage and/or 
> googling "debian list installed packages".  For backup, I think the 
> sacred files holding this data are in /var/lib/dpkg/.

dpkg -l grep '^i' gave me pages of incomprehensible stuff. dpkg --get
selections was a little better, but still not simple enough.

I think I just need to get a piece of paper and write down what is in
Applications.

> You can print this stuff on paper, but you could also feed it straight 
> into aptitude to keep it busy for a while once you've installed the 
> base packages.  If you're crossing a release boundary, some of the 
> package names will have been changed to protect the innocent and new 
> stuff will have 2s and 3s tacked on it.

Aptitude will not be running. I will wipe the partition and do a fresh
install.

> >I could also use a list of all configurations that I 
> > have made to Ubuntu, including a list of all repositories I have
> > enabled. And I could use a list of a lot of other things needed to
> > get me back where I am, things that I haven't even thought of yet.
> 
> Everything you've ever done as root to configure your system is in the 
> git history of your /etc/ directory iff you uses git to track changes 
> to your /etc/ directory.  Otherwise, it's going to be hard to tell the 
> difference between what you changed and the defaults.

Sadly, I don't know what git is. Guess I never used it.

> But even with a full history, upgrades often change the comments and 
> make a very noisy diff.  There are also scripts that run when you 
> install a package (and sometimes those ask you questions about stuff) 
> so it's no simple matter to extract the difference between defaults and 
> decisions.  You could diff your backup against the newly 
> installed /etc/, but that's likely to be a really big diff to read 
> through.  Replacing the files after install is not a good idea because 
> the package configuration scripts would have made changes to deal with 
> options in the new versions and lots of stuff would probably break.
> 
> Your repositories should be in /etc/apt/sources.list

At least that part I understand. I can make a printout
of /etc/apt/sources.list. 
> >I really don't want to do a reinstall, yet there is something messed up
> >in Xorg, Gnome, or bluetooth on my Jaunty laptop.
> 
> It still might be simpler to fix that than to start over.  Then setup 
> etckeeper or something so you have a record.

I have spent hours trying to fix it. The problem is figuring out what
is installed by a default fresh install, and compare that to what I
have installed. But that only discloses what I am missing. What if the
problem is that I have something installed that I should not have
installed? And we are not talking about half a dozen packages. It's at
least hundreds.

> When I upgrade across releases, I use dist-upgrade, so everything 
> in /etc is intact and most of the packages carry-over your old 
> settings.

So do I. But upgrading a broken installation is not likely to mend the
broken parts.