Re: Some newbie questions

["Jan Synáček" <jan.synacek@gmail.com>]

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On Thu, Oct 29, 2015 at 2:23 PM, Thompson, David <dthompson2@worcester.edu>
wrote:

> On Thu, Oct 29, 2015 at 6:08 AM, Jan Synáček <jan.synacek@gmail.com>
> wrote:
> > Hello,
> >
> > I've been playing with guix a bit and I must say I really like it. I
> don't
> > understand a few things though.
> >
> > 1) How do I tell if a package I have installed had been built locally or
> > downloaded as a substitute?
>
> You don't.  You can think of substitution is an optimization
> technique, the results are indistinguishable except for that it likely
> took less time to get the substitute.  It's possible to query the
> substitute server to see if it has the store item that you have, but
> that doesn't mean that your copy was retrieved from there necessarily.
> Other than that, the Guix tools will tell you at build/download time
> whether or not it is building from source or downloading a pre-built
> binary.  What use-case do you have in mind?


Nothing really specific. I was just curious if it was possible. Now that I
think about it,
I should get the same result whether building myself or installing a
substitute,
right?


> > 2) There are a lot of packages with executable binaries in the bin/
> > subfolder in /gnu/store. However, if I didn't explicitly install the
> > package, I don't have it in my profile and can't easily reach the binary
> > without first looking it up in the store. Do I have to always "install" a
> > package to be able to use run it easily?
>
> Not always, but usually that is what you'd do.  This is how we achieve
> isolation of environments.  Different users, or the same user in
> different circumstances, will want different sets of programs and
> libraries available to them.
>
> That said, if you just want to do a one-off run of something, you can
> use 'guix environment' instead, which will not install anything to
> your user profile, like so:
>
>     guix environment --ad-hoc wget -- wget http://gnu.org/s/guix
>
> > Please, excuse my not-so-clear questions, I still don't fully understand
> how
> > things really work in guix.
>
> No problem at all.  Welcome!
>
> - Dave
>

Thank you!

I'm curious about one more thing. In /gnu/store/, there are built packages,
which I understand.
Then there are derivations, -builder files, standalone statically linked
binaries, some patches
and also some scheme files. There's also the .links directory that contains
various file formats
as well, only this time their names are only hashes. Does any
documentation/source
of information about what all those are exist? I couldn't find anything.
The .links directory takes
over 2GiB on my machine and I wonder why.

Cheers,
-- 
Jan Synáček

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