add NIX_PATH

content/nixos/krops.md

@@ -498,3 +498,21 @@ in {
   ];
 }
 ```
+
+## Channels and NIX_PATH
+
+You might wonder how `nix-shell` is catching up with the
+`nixpkgs` in `/var/src`.
+
+`nix-shell` will still use the standard system setup,
+including your channel configurations,
+which you have to maintain on top of using krops.
+
+If you don't like to do that (like me) you have to change
+the `NIX_PATH` variable system-wide.
+
+```nix
+environment.variables.NIX_PATH = lib.mkForce "/var/src";
+```
+
+And `nix-shell` will also use `nixpkgs` from `/var/src`