nixos-option

List all subkeys of a given option key

$ nixos-option [option_key]

$ nixos-option boot.kernelModules

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

$ nixos-option nix.buildMachines

$ NIXOS_CONFIG=[path_to_configuration.nix] nixos-option [option_key]

$ nixos-option [[-r|--recursive]] users.users.[user]

nixos-option [options] [option-name]

--help
    Displays help text.

--version
    Shows the version number.

-j
    Use concurrent workers for evaluating Nix expressions. Defaults to the number of CPUs.

--eval-cache
    Enable the Nix expression evaluation cache. Can improve performance for repeated lookups.

--read-only-mode
    Do not allow option value setting. This option prevents accidental modifications during inspection.

[option-name]
    The specific option to query. If omitted, all options are displayed.

The `nixos-option` command provides a way to browse and query configuration options within the NixOS operating system. It allows users to discover available settings, understand their purpose, and view their default values. This is crucial for customizing NixOS systems to meet specific needs. The command retrieves information from the NixOS option definitions, often located within the Nixpkgs repository. It displays the option name, type, default value, description, and any relevant documentation. This helps administrators understand how to configure services, hardware, and other system aspects managed through NixOS's declarative configuration system. Users can filter options by name or type using various flags, making it easier to find the desired configuration setting. The command's output is formatted for readability, enhancing the user experience when exploring NixOS configuration possibilities.

The output is generally formatted for easy reading in a terminal. It typically includes the option name, type, default value, and a detailed description. The display can be influenced by command-line arguments.

Example:
`nixos-option services.openssh.enable`
Shows the details of the `services.openssh.enable` option.
Example:
`nixos-option`
Lists all available options (potentially very long).
Example:
`nixos-option services.openssh | less`
Lists information related to options under 'services.openssh', and pipes the output to 'less'.

Behind the scenes, `nixos-option` evaluates Nix expressions to determine the current values and descriptions of the options. This evaluation process is handled by the Nix package manager itself.

nix(1), nix-shell(1), nix-build(1)