nixos-option

inspects NixOS configuration values, showing what options are set and their

TLDR

Show an option's value, type, default and where it was set

$ nixos-option [services.openssh.enable]

List the children under a namespace

$ nixos-option [services.nginx]

Walk a whole subtree at once

$ nixos-option --recursive [users.users]

Check which kernel modules the configuration loads

$ nixos-option boot.kernelModules

Inspect a user's authorized SSH keys

$ nixos-option users.users.[username].openssh.authorizedKeys.keys

Look at the configured remote build machines

$ nixos-option nix.buildMachines

Query a configuration file other than the system one

$ NIXOS_CONFIG=[path/to/configuration.nix] nixos-option [option_key]

SYNOPSIS

nixos-option [options] optionpath_

nixos-option inspects NixOS configuration values, showing what options are set and their current values. It navigates the hierarchical NixOS module system using dot notation (e.g., services.nginx.enable).The tool displays the type, default value, description, and current value of configuration options. For container options (like services.* or users.*), it lists available subkeys.This is useful for exploring available NixOS options, debugging configuration issues, and understanding the current system state as defined by the Nix configuration.

PARAMETERS

-r, --recursive

Show all nested values recursively

_option_path_

Dot-separated path to the configuration option

NIXOS_CONFIG

Environment variable to specify an alternative configuration file

INSTALL

nix profile install nixpkgs#nixos-option

CAVEATS

Evaluates the Nix configuration, which can take time on complex systems. Only shows options from the NixOS module system; arbitrary Nix expressions are not inspectable. Some dynamic options may not be fully discoverable.