Following the chain of dependencies

[Marius Gedminas]

On Thu, May 07, 2009 at 02:14:05PM -0400, Brian McKee wrote:
> 2009/5/7 Markus Schönhaber <ubuntu-users at list-post.mks-mail.de>:
> >> I was surprised to learn that installing apticron on a server would
> >> drag in x11 !
> > Not for me (on a Jaunty server with no GUI installed):
> >> What's the best way to follow the chain of dependencies and figure out why?
> > I don't know of a general automatic way of following such a chain of
> > dependencies - maybe others can come up with one.
> > Manually, you can do something like
> > aptitude show <package name>
> > One of apticron's dependencies is debconf which, in turn, suggests
> > gnome-utils. Did you configure apt to automatically install suggested
> > packages?
> Nope

However Recommended packages are installed by default in Jaunty.

> Hmmm - maybe I'm getting what's going on here
> 
> ==> aptitude show apticron
> State: not installed
> Depends: apt-listchanges (>= 2.59), mailx, debconf | debconf-2.0,
> iproute, apt (>= 0.6.8)
> 
> Assuming it takes the first fork

I think you're interpreting the dependency list as

  (apt-listchanges >= 2.59 and mailx and debconf) or (debconf-2.0)

while it's really

  apt-listchanges >= 2.59 and mailx and (debconf or debconf-2.0)

> ==> aptitude show mailx
> Package: mailx
> State: installed
> 
> ==> aptitude show debconf
> Package: debconf
> State: installed
> 
> ==> aptitude show apt-listchanges
> State: not installed
> Depends: apt (>= 0.5.3), debconf | debconf-2.0, debianutils (>=
> 2.0.2), python (>= 2.4), python-apt, python-support (>= 0.7.1), ucf
> (>= 0.28)
> Recommends: exim4 | mail-transport-agent, python-glade2, python-gtk2
> Suggests: www-browser, x-terminal-emulator
> 
> For some reason it thinks if you don't have exim4 (I'm running
> postfix) you need the python GUI stuff, which I'm guessing leads back
> to x11 if you chase if far enough.

No, it always recommends python-glade2 (and python-gtk2).

> I wonder why?

I believe apt-listchanges has a GUI frontend, so it is usable when you
use update-manager or other GUI tools to do your upgrades.

This is a recommendation, not a dependency, so you can do

  sudo apt-get install --no-install-recommends apticron

or

  sudo aptitude install --without-recommends apticron

which, I see in the text quoted below, you've already discovered.

> I also have since determined that aptitude -D seems to show
> dependencies, but it's not very legible.

I sometimes use

  sudo apt-get install somepackageIwant thatotherpackageIdonotwant-

to explicitly tell apt I want one but not the other, and then see from
apt's error messages which dependency caused the conflict.

(Aptitude probably supports the same syntax.  I'm using apt-get since
I've learned it long ago and so far don't see a compelling advantage in
switching to aptitude.)

> So, I have a solution that seems to work - sudo aptitude -R install
> apticron...

> Thanks for prodding me along.

Marius Gedminas
-- 
We're sysadmins. To us, data is a protocol-overhead.
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