[Nix-dev] conflicting packages / priority values

[James Cook]

Roger, I'm not sure what you're suggesting. Do you mean that the user's
configuration would explicitly say "include pkgs.someAlternateGitVersion in
my profile, but rename /bin/git to /bin/gitB"?

As a starting point, I guess you could do that manually by making a new
expression with a build script like cp -r "$git" "$out"; mv "$out/bin/git"
"$out/bin/gitB".

On 17 June 2017 at 03:14, Roger Qiu <roger.qiu at matrix.ai> wrote:

> I wonder in other programming languages, name clashes are usually resolved
> through aliasing. Would it be possible for nix to install packages while
> aliasing their outputs to a different name to avoid clashes like this?
>
> On 17 Jun 2017 09:07, "Roni Choudhury" <aichoudh at gmail.com> wrote:
>
>> From time to time I see an error message like this:
>>
>> collision between ‘/nix/store/qs8fq5ld2shc0i3fvbs6n0g0k8fypndm-git-2.13.0/bin/git’ and ‘/nix/store/64fjdb4whkf2r5x8xyqf9kkljnk6w59b-git-2.13.0/bin/git’; use ‘nix-env --set-flag priority NUMBER PKGNAME’ to change the priority of one of the conflicting packages
>>
>> I understand what causes it (two packages competing to place the same,
>> e.g., binaries in my profile), but I’ve never understood how to resolve it.
>> Usually I just guess priority numbers until it works; more lately I’ve
>> simply removed the offending package from my environment before repeating
>> the failing install command. Obviously, neither approach is healthy or
>> correct :)
>>
>> The man page for nix-env contains the following:
>>
>> If there are multiple derivations matching a name in args that have the
>> same name (e.g., gcc-3.3.6 and gcc-4.1.1), then the derivation with the
>> highest priority is used. A derivation can define a priority by declaring
>> the meta.priority attribute. This attribute should be a number, with a
>> higher value denoting a lower priority. The default priority is 0.
>>
>> But I’m still not sure what this means for my error situation. How do I
>> know what the priorities are for the different packages? The default value
>> is 0, which is the highest priority; what does that mean exactly, for the
>> default priority to be the highest priority?
>>
>> Is there a more intuitive way to resolve this sort of conflict? For
>> instance, is there a way to tell nix-env to force the issue by treating
>> the requested package as higher priority than any existing ones?
>>
>> Thanks!
>>
>> roni
>> ​
>>
>> _______________________________________________
>> nix-dev mailing list
>> nix-dev at lists.science.uu.nl
>> https://mailman.science.uu.nl/mailman/listinfo/nix-dev
>>
>>
> _______________________________________________
> nix-dev mailing list
> nix-dev at lists.science.uu.nl
> https://mailman.science.uu.nl/mailman/listinfo/nix-dev
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.science.uu.nl/pipermail/nix-dev/attachments/20170617/4e08bd75/attachment-0001.html>