problems with 10.04 upgrade to 12.04

[Dave Howorth]

Avi Greenbury wrote:
> Dave Howorth wrote:
> 
>> I've already said that I don't understand apt and dpkg much but I'm
>> confused by why apt and dpkg show different things:
>>
>>  # apt-cache search 'python.*minimal'
> 
> Here you're asking apt for available packages
>>  # dpkg -l \* | grep minimal
> 
> Amd here you're asking dpkg for a list of installed packages.

Doh! Note to self: RTFM. I was using a tutorial at
http://newbiedoc.sourceforge.net/tutorials/apt-get-intro/info.html and
it says dpkg will show packages that aren't installed as well when given
the \*  And the fact that the dpkg header says

Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend

led me to believe that was true. But I now see that the man page doesn't
say that. And apt and dpkg can legitimately hold different state.

>> And what decides what should be installed?
>> i.e. why does apt-get say:
>>
>>   python-minimal: Depends: python2.7-minimal (>= 2.7.3) but it is not
>> going to be installed
> 
> The maintainer of the python-minimal package has said, when building
> the package, that it requires python2.7-minimal of version 2.7.3 or
> greater.
> 
> There's a few reasons it might be 'not going to be installed
> unfortunately, and apt is rarely clear on the reasons. You can try
> attempting explicitly installing it:
> 
>   apt-get install python2.7-minimal
> 
> to see if that is more wordy on reason. It's *possible* (but I'd hope
> unlikely) that 2.6 conflicts with 2.7.

Thanks for that explanation. It makes things a bit clearer for me. Sadly
the error message is the same hand-waving:

[long list of broken deps snipped]
E: Unmet dependencies.

(aside: I have to say, I do find ZYpp and friends a whole lot easier to use)