View source for How to fetch Nixpkgs with an empty NIX PATH

You can fetch Nixpkgs with an empty <code>NIX_PATH</code>.  This
comes in handy if you want to remove impure references to the <code>NIX_PATH</code> from
your code base.

To do so, you can use <code>builtins.fetchTarball</code>, like this:

<syntaxhighlight lang="nix">
let
  nixpkgs = builtins.fetchTarball {
    url    = "https://github.com/NixOS/nixpkgs/archive/3389f23412877913b9d22a58dfb241684653d7e9.tar.gz";
    sha256 = "0wgm7sk9fca38a50hrsqwz6q79z35gqgb9nw80xz7pfdr4jy9pf8";
  };

  pkgs = import nixpkgs { config = {}; };

in
  ...
</syntaxhighlight>

… replacing <code>3389f2…</code> with the desired revision of Nixpkgs and replacing <code>0wgm7s…</code> with the corresponding SHA256 hash.

You can use the following command to obtain the correct SHA256 hash to use if you prefer not to use trial and error:

<syntaxhighlight lang="bash">
$ nix-prefetch-url --unpack "https://github.com/NixOS/nixpkgs/archive/${REVISION}.tar.gz"
</syntaxhighlight>

[[Category:Nix]] [[Category:Nixpkgs]] [[Category:Cookbook]]