Re: doc: Proposed note about symlinks in section "invoking guix pull"

[ludo@gnu.org (Ludovic Courtès)]

Hi,

swedebugia <swedebugia@riseup.net> skribis:

> On 2018-11-14 12:23, Ludovic Courtès wrote:
>> Hello,
>>
>> swedebugia <swedebugia@riseup.net> skribis:
>>
>>> "Note: if your have wound up with a faulty guix after a "guix pull" you can manually run an older version by looking at the symlinks in your /user/home/.config/guix/ directory.
>>> E.g. if it lists:
>>> $ ls -l /root/.config/guix/
>>> total 0
>>> lrwxrwxrwx 1 root root 33 Nov  4 01:24 current -> /root/.config/guix/current-1-link
>>> ...
>>> Then your faulty guix is in current-1-link, and your former probably well working guix is in an older symlink, e.g. current-2-link.
>>> To run the guix-version before the last pull in the example above, run:
>>> /root/.config/guix/current-2-link/bin/guix
>>>
>>> Now go ahead and use that older guix to roll back as described above."
>>>
>>> What do you think?
>>
>> I think you’re describing a terrible bug, but a bug that’s behind us
>> AFAIK.  I’m reluctant to documenting an old bug that’s hopefully no
>> longer relevant; I think it would clutter the manual.
>
> What makes you think it is behind us?

I think commit aa227b3be3d7728331a08dbd139c47c9b271dc23 fixes it.  No
matter how old the Guix you’re updating from is, you shouldn’t have this
symlink problem.

> There are probably a handful of our users who has old guix installations.
>
> This will not go away anytime soon unless we state very clearly how to
> deal with it when they try to "pull". Maybe the manual is not the best
> place for this.
>
> We could start by putting a big WARNING to users somewhere noticeable
> when the guix they run is deprecated beyond repair.

No, I think that’s a misunderstanding of the problem.

If you run ‘guix pull’ from 0.15.0, say, it will complete fine.  Next
time you run ‘guix pull’ or ‘guix pull -l’, it will automatically
move ~/.config/guix/current-*-link to /var/guix/profiles/per-user/$USER.

The bug was that this automatic migration was buggy prior to
aa227b3be3d7728331a08dbd139c47c9b271dc23, which could leave you with
broken symlinks.

I hope this clarifies the situation!

Thanks,
Ludo’.