[Nix-dev] nix-shell is unable to install the package which nix-env just returned

[Guillaume Maudoux (Layus)]

Hmm.. could it be that your system is confused by multiple channels ?

What's the output of (normal user)
$ nix-channel --list

I think your best bet is `nix-shell "<nixpkgs>" -p letsencrypt`
where nixpkgs is your channel name.

You can even go further and set the nixpkgs path directly using
nix-shell
/nix/store/7kxsv9svwcaxzkxxjg0zxcb151mic8vw-nixos-16.03pre76756.885acea/nixos/nixpkgs
-p letsencrypt

nix-env can also take such a path

To inspect your system state, try to run
$ nix-instantiate --eval --expr --strict "<nixpkgs>"
$ nix-instantiate --eval --expr --strict "<nixos>"
$ sudo nix-instantiate --eval --expr --strict "<nixpkgs>"
$ sudo nix-instantiate --eval --expr --strict "<nixos>"

<nixpkgs> gets evaluated in the context of the current user, so you will
get very different results when using sudo.

To ensure a consistent result, you can also pass the nixpkg tree to
nix-env with option -f.
$ nix-env -qaP -f "<nixpkgs>"

Now, there is no reason for the attribute returned by `nix-env -f
"<nixpkgs>" -qaP` to be missing when calling `nix-shell "<nixpkgs>" -p`
because the nixpkgs are exactly the same.

All this highlights the inconsistency between (and within) the tools.
But that's another story :-).

Layus.

Le 31/03/16 11:25, Dmitry Malikov a écrit :
> >> nix-shell -p nixpkgs.pkgs.letsencrypt
> error: undefined variable ‘nixpkgs’ at (string):1:66
> (use ‘--show-trace’ to show detailed location information)
>
> Any other ideas?
>
> On 31 March 2016 at 10:37, Arseniy Seroka <ars.seroka at gmail.com
> <mailto:ars.seroka at gmail.com>> wrote:
>
>     nix-shell -p nixpkgs.pkgs.letsencrypt
>
>     -- 
>     Sincerely,
>     Arseniy Seroka
>
>     On 31 March 2016 02:21:40 Dmitry Malikov <malikov.d.y at gmail.com
>     <mailto:malikov.d.y at gmail.com>> wrote:
>
>>     >> sudo nix-channel --list
>>     nixpkgs https://nixos.org/channels/nixpkgs-unstable
>>     nixos https://nixos.org/channels/nixos-15.09
>>
>>     >> nixos-version
>>     15.09.1180.e8e1cb8 (Dingo)
>>
>>     >> nix-env --version
>>     nix-env (Nix) 1.10
>>
>>     Anything else?
>>
>>>     On 31 Mar 2016, at 00:45, Jonn Mostovoy <jm at memorici.de
>>>     <mailto:jm at memorici.de>> wrote:
>>>
>>>     Just worked for me, exactly the same command.
>>>     My version of nixpkgs is way older though.
>>>
>>>     On Mar 31, 2016 12:40 AM, "Dmitry Malikov"
>>>     <malikov.d.y at gmail.com <mailto:malikov.d.y at gmail.com>> wrote:
>>>
>>>         >>
>>>         nix-env -qaP '*' | grep letsencrypt
>>>         nixpkgs.letsencrypt                                                    
>>>         letsencrypt-0.4.0
>>>
>>>         >> nix-shell -p letsencrypt
>>>         error: undefined variable ‘letsencrypt’ at (string):1:66
>>>         (use ‘--show-trace’ to show detailed location information)
>>>
>>>
>>>         What am I missing here?
>>>
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>>
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>
>
>
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