Re: Few questions regarding the installation

[Wolf <wolf@wolfsden.cz>]

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Hello,

On 2022-12-17 03:41:17 +0100, Tobias Geerinckx-Rice wrote:
> Hi Wolf,
> 
> Wolf 写道：
> > But it is not on the path:
> > 
> >     root@gnu ~# pvcreate
> >     bash: pvcreate: command not found
> 
> Indeed, lvm2(-static) wasn't actually installed on the installation image!
> 
> Commit 0906ce7389c6654fa3d1b3b52c8330eff0256264 fixes that:
> 
>  root@gnu ~# which pvcreate
>  /run/current-system/profile/sbin/pvcreate

Great, so since 1.5.0 this will be taken care of (since I do not see
it in the 1.4.0 tree).

> 
> > On IRC I was advised to try guix install lvm2-static, which does work
> > (after sourcing the profile), however it does download the package
> > from the internet.
> 
> The installer image was generated using ‘guix system image’ with particular
> Guix version N.  Hence, all packages inside that image are those from Guix
> version N.  (In Guix, there is no ‘package repository’ distributed
> separately from the ‘package manager’.) These packages include the image's
> ‘guix’ package itself.
> 
> Hence, the ‘guix’ you can run in the image will always be older than the
> Guix that put lvm2-static in the image, and may contain older versions of
> some packages.
> 
> You'll have Guix N's lvm2-static in /gnu/store, but ‘guix install
> lvm2-static’ will install Guix N-1's version.  They might match, they might
> not.  I guess here they didn't.

Ah, based on this my understanding is that just the fact that
something is in the store does not mean it is actually installed. It
could be just a left over, or something pulled as a dependency. And
since lvm2{,-static} is not actually installed, it is not symlinked
into any usable path (even though is it present in the store).

Is that roughly correct summary? Sorry, this is my first try at the
guix/nix approach to things, so I want to be sure I understand it
properly.

> 
> >                    That seems pointless, since I already have
> > one
> > locally (as seen in the output of find above), so I would prefer to
> > use that one.
> 
> You can simply
> 
>  root@gnu ~# guix install /gnu/store/84n[…]-lvm2-static-2.03.1
> 
> That might still download $things for $reasons, but they won't include
> lvm2-static.
> 

It seems to still download $things for $reasons (quite few of them,
including mkfontscale for example). Since this is already resolved on
the master, for now I'll go with

    # This should not longer be necessary since guix 1.5.0
    if ! command -v pvcreate >/dev/null; then
    	guix install lvm2-static
    	GUIX_PROFILE="/root/.guix-profile"
    	. "$GUIX_PROFILE/etc/profile"
    fi

and call it a day. I will make a note to try to figure out $reasons at
some later time.

> > Another question is how to undo the effect of running herd start
> > cow-store /mnt. I did try the obvious (herd stop cow-store), but that
> > does not seem to do the trick. So, how can I do it?
> 
> This I don't know either.  I always just reboot.
> 
> Kind regards,
> 
> T G-R

Thank you for the help.

W.

-- 
There are only two hard things in Computer Science:
cache invalidation, naming things and off-by-one errors.

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