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Re: Downgrading packages (with dependencies)



In <[🔎] 201011161438.54964.jesus.navarro@undominio.net>, Jesús M. Navarro wrote:
>Hi, Boyd:
>
>On Monday 15 November 2010 20:55:58 Boyd Stephen Smith Jr. wrote:
>> In <[🔎] 201011151334.06503.lukas.linhart@centrumholdings.com>, Lukas Linhart
>
>[...]
>
>> Downgrades aren't supported and can't reasonably be supported in general.
>> Specifically, it is impossible to modify the lower-versioned package to
>> account for changes brought in by the higher-versioned package.
>
>It's true that they are not currently supported on Debian, but I don't see
>that they can't be supported.
>
>Downgrade shouldn't be considered as an "upgrade, only to a lower version"

That is what a downgrade is, by definition.

>but more as of a rollback: regarding configs and binaries it seems not so
>complex; just recover whatever was there prior to the upgrade

That's something entirely different and intentionally not handled by the 
packaging system.  There are a few roll-your-own solutions available for 
Linux, but I don't know of something like Apple's Time Machine that works out-
of-the-box.

The critical difference is that the packaging system restricts it's actions to 
system-wide programs and data (and tries to concentrate as much as possible on 
static data; avoiding as much as possible data that is modified during normal 
operations), whereas a rollback has to include user-specific data which can be 
very dynamic.

Yes, you have to the user's data as well.  While packages don't install to 
/home, running programs often write there and files written by the higher 
versions of a program may not be readable by the lower versions of a program.

If you want rollbacks, get a system that handles rollbacks.  Don't expect the 
packaging system to do it as implicitly on a downgrade request.
-- 
Boyd Stephen Smith Jr.                   ,= ,-_-. =.
bss@iguanasuicide.net                   ((_/)o o(\_))
ICQ: 514984 YM/AIM: DaTwinkDaddy         `-'(. .)`-'
http://iguanasuicide.net/                    \_/

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