[GLLUG] Upgrading Ubuntu and Debian releases (was: Re: Problems with CentOS 4 to 5 upgrade)

[John Edwards]

Hi Jan

On Fri, Nov 24, 2017 at 05:40:16PM +0000, Jan Henkins via GLLUG wrote:
> On 24 November 2017 17:23:18 GMT+00:00, Alain Williams via GLLUG <gllug at mailman.lug.org.uk> wrote:
<snip>
>> In spite of that I would suggest that an occasional clean reinstall is
>> not a bad
>> idea. That way you get rid of the crud that is installed but is no
>> longer needed.
>> A good update system cannot always remove crud.
> 
> Absolutely correct. In an ideal world I try to do this either every other distro in the case of Debian, or go for completely new installations for each new Ubuntu LTS release. Most of the time this doesn't work (normally too many 3rd party repositories, my own fault), so I always have backups handy to help me un-fubar the situation. On my servers things are a lot more predictable, since I rather go for small specialist VMs that does as few jobs as possible. Virtualisation is awesome! 
> 

I think the presence of packages from third party repositories would
be the main reason that an upgrade would fail on Debian or Ubuntu.

Ubuntu has the 'do-release-upgrade' tool which I've used to upgrade
lots of Ubuntu LTS machines (mainly servers also) for about 7 years.
The only time we have been forced to do a reinstall for OS reasons is
to convert a system from 32-bit to 64-bit (never found a easy way to
do that).

Desktop machines usually have more packages installed on them with
greater dependencies, so they can be more troublesome.But I would
still expect them to be upgradable.

Debian/Ubuntu package upgrade should prompt to upgrade package config
files, and leave a .dpkg-new or .dpkg-old (depending on your answer)
in case you change your mind or need to import previous changes.

The 'deborphan' tool can spot some unrequired packages, as can
'apt-get autoremove'. The Debian 'cruft' tool looks for non-package
files, but I've not run it in a long time.



-- 
#---------------------------------------------------------#
|    John Edwards   Email: john at cornerstonelinux.co.uk    |
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