| name | nixos-options |
| description | Skill for evaluating, searching, and inspecting authoritative NixOS options from local nixpkgs using nix eval. |
Querying NixOS Options via nix eval
When reverse-engineering system settings into NixOS configuration options, query local nixpkgs directly to discover precise option names, types, and defaults.
1. List Sub-Attributes of an Option Path
nix eval --json --impure --expr '
let
eval = import <nixpkgs/nixos/lib/eval-config.nix> { modules = []; };
in builtins.attrNames eval.options.<attribute.path>
'
Example:
nix eval --json --impure --expr 'let eval = import <nixpkgs/nixos/lib/eval-config.nix> { modules = []; }; in builtins.attrNames eval.options.security.pam'
2. List Sub-Options of Dynamic Sets (e.g. services.<name>, luks.devices.<name>)
nix eval --json --impure --expr '
let
eval = import <nixpkgs/nixos/lib/eval-config.nix> { modules = []; };
in builtins.attrNames (eval.options.<attribute.path>.type.getSubOptions [])
'
3. Inspect Full Metadata (Type, Default, Description) for an Option
nix eval --json --impure --expr '
let
eval = import <nixpkgs/nixos/lib/eval-config.nix> { modules = []; };
opt = eval.options.<attribute.path>.<option_name>;
in {
type = opt.type.name;
description = opt.description or null;
default = opt.default or null;
}
'
