Invoke `nix` on unsupported/unknown subcommands

[Lorenz Leutgeb]

I did alias nix=nom, and was very pleased with my new nix build experience. Then, I wanted to run nix repl, and was frustrated that nom does not "forward" this command to nix transparently, i.e., it did not invoke nix repl.

As long as you don't support all nix subcommands, please consider to just invoke nix: The command nom foobar should invoke nix foobar.

In the meantime, I'll be using this workaround via Home Manager:

pkgs.writeShellApplication {
  name = "nix-nom";
  text = ''
    set -euo pipefail
    if [ "$1" = "build" ] || [ "$1" = "shell" ] || [ "$1" = "develop" ]
    then
      ${pkgs.nix-output-monitor}/bin/nom "''${@:1}"
    else
      ${osConfig.nix.package}/bin/nix "''${@:1}"
    fi
  '';
}

(and alias nix=nix-nom)

[maralorn]

I have pondered this for quite a while and I certainly want a good solution for this. Sadly I see a huge footgun potential here. nom takes nix from the PATH. In your case with the alias you are actually fine, but imagine someone using a symlink nix -> nom, then nom will recusively call itself.

[maralorn]

Ah, well. You actually don't set nix -> nom.

[Lorenz Leutgeb]

I agree that symlinking nix -> nom is a no-go. Also, removing nix from $PATH is a no-go.

In some cases (nom [build|develop|shell]) nom will exec nix anyway. I am asking that nom also does this for any other subcommand.

Whether someone wants to alias nix=nom is a different matter. I am not suggesting that nom should do aliasing, but I am asking to really support aliasing. For me, when I read "drop in replacement" (like in your README) I expect a plain alias to work. And not just for a few subcommands, but for all of them. See e.g. mislav/hub where you have an alias git=hub situation.

If I ever have a problem with the alias, I just remove it and run nix directly.

[maralorn]

Point taken. I had this on my radar anyway and will look into it.

[Xandor Schiefer]

@lorenzleutgeb you can have a look at my code in #108 to create your own aliases. It's not 100% battle-tested but it's a starting point.

[Lorenz Leutgeb]

Thanks @zeorin, that's super cool to see, but way too involved for me at the moment.