Warning: This program is experimental and its interface is subject to change.


nix registry add - add/replace flake in user flake registry


nix registry add [option...] from-url to-url


  • Set the nixpkgs flake identifier to a specific branch of Nixpkgs:

    # nix registry add nixpkgs github:NixOS/nixpkgs/nixos-20.03
  • Pin nixpkgs to a specific revision:

    # nix registry add nixpkgs github:NixOS/nixpkgs/925b70cd964ceaedee26fde9b19cc4c4f081196a
  • Add an entry that redirects a specific branch of nixpkgs to another fork:

    # nix registry add nixpkgs/nixos-20.03 ~/Dev/nixpkgs
  • Add nixpkgs pointing to github:nixos/nixpkgs to your custom flake registry:

    nix registry add --registry ./custom-flake-registry.json nixpkgs github:nixos/nixpkgs


This command adds an entry to the user registry that maps flake reference from-url to flake reference to-url. If an entry for from-url already exists, it is overwritten.

Entries can be removed using nix registry remove.


  • --registry registry
    The registry to operate on.

Common evaluation options:

  • --arg name expr
    Pass the value expr as the argument name to Nix functions.

  • --argstr name string
    Pass the string string as the argument name to Nix functions.

  • --eval-store store-url
    The Nix store to use for evaluations.

  • --impure
    Allow access to mutable paths and repositories.

  • --include / -I path
    Add path to the list of locations used to look up <...> file names.

  • --override-flake original-ref resolved-ref
    Override the flake registries, redirecting original-ref to resolved-ref.