Translations:FAQ/31/en

# /etc/nixos/configuration.nix
{ config, pkgs, lib, ... }:
{
  nix.settings = {
    keep-outputs = true;
    keep-derivations = true;
    # See https://nixos.org/manual/nix/stable/command-ref/conf-file.html
    # for a complete list of Nix configuration options.
  };
}

Check 'man configuration.nix' for these options. Rebuild for these options to take effect: