From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: guix-gc
Date: Thu, 10 Jan 2013 13:40:25 +0100
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References: <8738yfp4j7.fsf@gnu.org> <201301101104.22164.andreas@enge.fr>
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In-Reply-To: <201301101104.22164.andreas@enge.fr> (Andreas Enge's message of
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To: Andreas Enge <andreas@enge.fr>
Cc: bug-guix@gnu.org

Hi!

Andreas Enge <andreas@enge.fr> skribis:

> When running "guix-gc" without specifying any root, the complete content =
of=20
> /nix/store was classified as dead. This looks a bit excessive to me; shou=
ld=20
> not at least the gnu build system that would be used to build a package=20
> with the currently installed guix be preserved? Even if the user has not=
=20
> installed gcc in his environement, for instance, the "current" gcc should=
=20
> be kept, whereas any older gcc (I had quite a few of them corresponding t=
o=20
> several versions of guix) should be deleted.

Well, anything that=E2=80=99s not reachable from a GC root is deleted.

Nix provides other options that extend this model to something closer to
what you say, namely =E2=80=98gc-keep-outputs=E2=80=99 (see
<http://hydra.nixos.org/build/3676991/download/1/nix/manual.html>.)

I guess we should add a guix-daemon option for that.

> If I see it correctly, this means that the output of
>    guix-build hello --dry-run
> should be kept in the store.

Currently it=E2=80=99s not the case, unless you use:

  guix-build --root=3Dmy-hello hello

and the keep the =E2=80=98my-hello=E2=80=99 symlink around.

> I also got the following error on the first run:
>
> deleting `/nix/store/j29s9129di8lzx7xbc9rj0ywx05pivij-readline-6.2'
> error: build failed: getting status of=20
> `/nix/store/j29s9129di8lzx7xbc9rj0ywx05pivij-readline-6.2': No such file =
or=20
> directory
>
> But the next run worked and deleted everything.

Hmm, weird.  If that happens again, perhaps you should try to see where
that directory is, by looking at /nix/store and at --list-dead and
--list-live, for instance.

Thanks,
Ludo=E2=80=99.