Set a option with its default value in nixos configuration

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1

I want to add a new path into nix.nixPath. I have some options to do this, such as edting NIX_PATH in shell’s profiles.

But I want to set it in configuration.nix. I can get default value from website or nixpkgs repo.
I wonder how I can get it using nix expression in configuration.nix. I know it is lazy in config, so using argument named config cannot work.

For example(what i want to do):

{ config, ... }:
{ a = config.a ++ [ sth ]; }
2

List options are merged, not replaced, so { a = [ sth ]; } should be enough.

3

my system version is 19.03, and it is replaced, not merged.
The only merged one is systemPackgaes, the other, such as nix.nixPath is not for me

4

Give

nix.nixPath = mkOptionDefault [
  "my-path=/the/path/you/want/to/add"
];

a try if you want to merge with the option’s default value.

3 Likes
5

This can work. Thanks.

6

As an alternative, more literal approach, this could work:

{ config, options, ... }:
{ nix.nixPath = options.nix.nixPath.default ++ [sth]; }
1 Like