How to upgrade in place from 16.10 unity to 17.04 gnome

[Brian Burch]

Thanks Marius,

This is short top-post because I won't respond inline to your valuable 
comments and suggestions at the moment. However, I didn't want you think 
I wasn't paying attention! I am grateful for your input.

I often run virtual machines on that particular system, so I ought to be 
able to do a clean install under unity to get both full package lists, 
because I have now upgraded my desktop system in-place to 17.04.

Unfortunately, that particular machine dropped dead suddenly at the 
weekend and it looks as if I need a new computer (it was 12 years old). 
Once I have that unplanned activity sorted out, I'll let you know how I 
get on with the desktop change.

This laptop runs ubuntu studio 17.04, with lightdm and xfce4, so I 
couldn't easily use it to test (besides, I need to do some problem 
determination on why bcmwl-kernel-source has broken my laptop wifi!).

Don't hold your breath, but I WILL reply to you properly once my 
technical life is back under control.

Thanks again,

Brian

p.s. your suggestions are OK for me, but not for most of the ordinary 
users. It's a pity we can't come up with something safe and easy.


On 27/04/17 22:45, Marius Gedminas wrote:
> On Thu, Apr 20, 2017 at 02:17:26PM +1000, Brian Burch wrote:
>> On 17/04/17 18:10, Pander wrote:
>>> To remove Unity, I simply use dpkg -P packagenames. When that list
>>> becomes long from many dependencies, I put the output of that
>>> through grep to get all the depending packages and cat those to a
>>> file. Edit the file (vim and a lot of Shift-j) and put dpkg -P at
>>> the beginning. I use the same trick for ouput of dpkg -l|grep -v ^ii
>>>
>>> Of course, check if those lists of package names are okay to purge
>>> before doing bulk purges. Some packages are tricky, see my post a
>>> while back on Unity dependencies.
>>
>> Thanks for your suggestion, Pander. I did something fairly similar to that
>> in the past. If I decide to go ahead this time, then I will follow your plan
>> because it seems simpler than what I did before.
>>
>> However, I was hoping to receive advice that would be attractive and useful
>> to people who are not as confident as us with these low-level tools.
>>
>> Am I correct in thinking the "old method" of installing gnome-desktop
>> alongside unity has become too complex to be worth trying?
>
> Have you tried it?
>
> I did that a long time ago and it worked for me.  I haven't had the
> chance to try it lately.
>
> Installing the gnome metapackage and removing the unity metapackage
> ought to suffice, IMHO.  You might need to hunt down some other packages
> that differ between Unity and GNOME (e.g. the bootsplash theme).
>
> If I weren't a lazy person, I'd install both in two virtual machines,
> then compare the lists of installed packages (e.g. dpkg -l) so I would
> know which ones to install and remove to turn one into the other.
>
>> I tried "sudo dpkg --purge --dry-run unity" (-P is the same as --purge) on
>> my xenial system "just for fun", but it bombed out with a "too many
>> dependencies" error. However, it didn't list ANY of them!
>
> dpkg is too low-level for this; don't use it.  apt purge exists these
> days, and it deals with dependencies correctly.
>
> (AFAIU the only reason to remove/purge Unit packages is in case they
> install some system-wide gsettings override files that change some GNOME
> settings defaults to Unity defaults.  )
>
>> Perhaps I should just wait for the next ubuntu release and hope there will
>> be a more straightforward conversion path?
>
> A full reinstall is always a good way to test your backup completeness
> ;)
>
> Marius Gedminas