Debian dependencies

[Marc Lijour]

On Wednesday 23 November 2005 11:01, Lennart Sorensen wrote:
> On Tue, Nov 22, 2005 at 10:25:03AM -0500, phil wrote:
> > Some time ago I put a spare 6GB drive in my Intel box to try out
> > Debian.  Mostly, I like it...enough so that I'm filling up the disk.
> >
> > Before scratching my main SuSE installation, though, I thought I'd
> > clean up some of the packages I'm not using and see what that did to my
> > disk space.  Since I don't use sound on this system at all, I figured
> > getting rid of sound items that were marked "optional" made sense.
> > That idea, however, caused KPackage to recommend the removal of all (or
> > most) of KDE, which seemed a little extreme!
> >
> > How does one better control dependencies so that uninstalling things
> > doesn't unravel the universe?
>
> Well I have never used kpackage really being in my opinion one of the
> worst gui package managers I have ever encountered.  synaptic is a lot
> better and actually maintained by debian people.
>
> aptitude is better yet in my opinion (being curses, not graphical) and I
> tend to just use apt-get and dpkg myself.  The command line tools will
> clearly list what they are going to do so I can decide if it is correct.

kpackage and aptitude are gui front-ends for apt.

As you know packages are dependent on others, and those depends on others... 
Finally you end up with strange behaviors.

The installation problem is NP-Complete as demonstrated in this recent work:
http://www.edos-project.org/xwiki/bin/download/Main/Deliverables/edos-wp2d1.pdf

Installation, hot deployment and dependency solving is a hot topic. Big 
organizations are working on it such as OASIS.
http://www.w3.org/Submission/2004/SUBM-InstallableUnit-PF-20040712/

OSGI is also very nice, but that s a little off-topic.
http://www.osgi.org/documents/osgi_technology/osgi-sp-overview.pdf

> The problem with some of the "friendly" tools is that they will try
> uninstalling anything automatically installed as a dependancy when the
> thing causing the installation in the first place is removed.  For
> example if you install the package 'kde' it depeds on all things kde.
> If you later uninstall something from kde, it will of course have to
> remove the 'kde' meta package since you are removing one of the things
> it depends on.  Some "clever" package managers then go: You are removing
> 'kde' which was the reason I installed all this other stuff, so I will
> be "helpful" and remove all those for you.  This was not what you wanted
> in this case, but often for library dependancies of a package, it would
> be what you want.  After all if you install foo and it depends on
> libbar, it would be handy that removing foo will remove bar if nothing
> else depends on it.  Since package 'kde' was the only thing installed
> causing everything else to be installed, nothing else depends on the kde
> components so the same rule says you must want to uninstall all or most
> of kde.  Sometimes helpful isn't.  Sometimes friendly isn't.
>
> Doing apt-get remove kdesoundthingy will only remove the things that it
> must remove to make the dependancy tree valid.  The friendly tool may
> still offer to clean up later unless you go tell it you actually want
> those other things to stay installed by flagging them as such.
>
> Lennart Sorensen
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