.Dd January 1, 1980
.Dt nixos-option 8
.Os
.Sh NAME
.Nm nixos-option
.Nd inspect a NixOS configuration
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.Sh SYNOPSIS
.Nm
.Op Fl r | -recursive
.Op Fl I Ar path
.Ar option.name
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.Sh DESCRIPTION
This command evaluates the configuration specified in
.Pa /etc/nixos/configuration.nix
and returns the properties of the option name given as argument.
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.Pp
When the option name is not an option, the command prints the list of attributes
contained in the attribute set.
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.Sh OPTIONS
.Bl -tag -width indent
.It Fl r , -recursive
Print all the values at or below the specified path recursively.
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.It Fl I Ar path
This option is passed to the underlying
.Xr nix-instantiate 1
invocation.
.El
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.Sh ENVIRONMENT
.Bl -tag -width indent
.It Ev NIXOS_CONFIG
Path to the main NixOS configuration module. Defaults to
.Pa /etc/nixos/configuration.nix Ns
\&.
.El
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.Sh EXAMPLES
Investigate option values:
.Bd -literal -offset indent
$ nixos-option boot.loader
This attribute set contains:
generationsDir
grub
initScript

$ nixos-option boot.loader.grub.enable
Value:
true

Default:
true

Description:
Whether to enable the GNU GRUB boot loader.

Declared by:
  "/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/nixos/modules/system/boot/loader/grub/grub.nix"

Defined by:
  "/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/nixos/modules/system/boot/loader/grub/grub.nix"
.Ed
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.Sh SEE ALSO
.Xr configuration.nix 5
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.Sh AUTHORS
.An -nosplit
.An Nicolas Pierron
and
.An the Nixpkgs/NixOS contributors