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What's that thing with --extra-experimental-features?

So I tried to follow some tutorial about flakes, but it seems these are extra-experimental still.

I am using NixOS 23.11 with Nix 2.18.1 in a VM (those are the most recent stable versions, right?).

Trying around I already found out that instead of eg. nix flake update I have to use --extra-experimental-features two times to get this simple command:

nix --extra-experimental-features nix-command --extra-experimental-features flakes flake update

Searching the web I found several different things that people put into their /etc/nixos/configuration.nix to enable this globally, but none of those worked for me. I assume there is still a way to do this - can someone please tell me the correct syntax for Nix 2.18.1?

What makes things worse is that I cannot start playing around with home-manager and flakes, because home-manager switch flake . seems to use nix flake internally, which leads to errors instead of results.

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4 comments
  • @silmaril You can combine the flag --extra-experimental-features "nix-command flakes" or use nix.settings.extra-experimental-features = [ "nix-command" "flakes" ];

    • Thank you very much!

      nix.settings.extra-experimental-features = [ “nix-command” “flakes” ];
      seems to actually work in my setup.

      And it's nice to know that I can make do with one --extra-experimental-features argument for several features at once.

      May I be so bold as to ask a follow-up question that doesn't have much to do with this one?

      What do I have to do to get Virtualbox Guest Additions to work on NixOS? Not having a shared clipboard is driving me crazy ;-)

      Once again everything I found on the internet leads to errors during sudo nixos rebuild. I hope it's just another case of knowing the correct names for the actual packages or options to use.

      Can someone help me here?