[Nix-dev] nix store: hardlink vs symlink (was Re: python application vs python environment)

[Florian Friesdorf]

On Sun, 25 Sep 2011 22:23:57 +0200, ludo at gnu.org (Ludovic =?iso-8859-1?Q?Court=E8s?=) wrote:
> Florian Friesdorf <flo at chaoflow.net> skribis:
> 
> > On Sat, 24 Sep 2011 21:56:02 +0200, ludo at gnu.org (Ludovic =?iso-8859-1?Q?Court=E8s?=) wrote:
> >> Hi Florian,
> >> 
> >> Florian Friesdorf <flo at chaoflow.net> skribis:
> >> 
> >> > Why is nix using symlinks to link files in the nix store?
> >> 
> >> Because hard links don’t work across devices.
> >
> > But the links would be just intra-store links, or?
> 
> Sorry, I thought you were referring to why profiles use symlinks to the
> store.
> 
> Within a store, using hard links is OK, yes, and ‘nix-store --optimise’
> does exactly that.

But I think thats for a different purpose: An expression installs a
programm into a derivation. If two of them have the exact same file,
nix-store --optimise will hardlink them. If now two derivations are put
together into a new derivation, their components will be symlinked and
here, as I understand now, hardlinks are not an option because nix uses
the symlinks to store information about dependencies.

-- 
Florian Friesdorf <flo at chaoflow.net>
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