Breezy -> Dapper - adept wants to remove 295 packages

[John L Fjellstad]

"Michel D'HOOGE" <michel.dhooge at gmail.com> writes:

> IIRC all packages installed outside of aptitude are flagged as
> "manually installed". aptitude isn't confused but it won't remove them
> automagically if they are no longer needed. Another solution, within
> aptitude, is to mark the really important packages as "manually
> installed" ('m' and 'M' shortcuts). You can mark a bunch of packages
> at once by applying the shortcut to the upper folder.

There is more too it than that, isn't it?  Otherwise, we wouldn't see
the massive uninstallations that happen when you mix apt-get and
aptitude. 

>From what I can gather, something like this happens.
You install program A that depends on library libA with aptitude.
aptitude marks libA as automatically installed, and will remove it
if A gets removed.
You then install program B that depends on library libA with apt-get.
At this point, doesn't know that program B is depended on libA (in the
automatic sense, dpkg seems to know the dependency graph).

You then try to remove (or upgrade) program A with aptitude.  aptitude
sees that libA got installed with program A, and sends the request to
remove A and libA while-you-are-at-it to dpkg.  dpkg notices that B was
dependent on libA, so removes that too.

So, if you set libA to 'manually installed', aptitude won't request to
remove libA if A is removed.

-- 
John L. Fjellstad
web: http://www.fjellstad.org/          Quis custodiet ipsos custodes