Re: guix-gc

[ludo@gnu.org (Ludovic Courtès)]

Hi!

Andreas Enge <andreas@enge.fr> skribis:

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

Well, anything that’s not reachable from a GC root is deleted.

Nix provides other options that extend this model to something closer to
what you say, namely ‘gc-keep-outputs’ (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’s not the case, unless you use:

  guix-build --root=my-hello hello

and the keep the ‘my-hello’ 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 
> `/nix/store/j29s9129di8lzx7xbc9rj0ywx05pivij-readline-6.2': No such file or 
> 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’.