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1<refentry xmlns="http://docbook.org/ns/docbook"
2 xmlns:xlink="http://www.w3.org/1999/xlink"
3 xmlns:xi="http://www.w3.org/2001/XInclude">
4 <refmeta>
5 <refentrytitle><command>nixos-option</command>
6 </refentrytitle><manvolnum>8</manvolnum>
7 <refmiscinfo class="source">NixOS</refmiscinfo>
8<!-- <refmiscinfo class="version"><xi:include href="version.txt" parse="text"/></refmiscinfo> -->
9 </refmeta>
10 <refnamediv>
11 <refname><command>nixos-option</command></refname>
12 <refpurpose>inspect a NixOS configuration</refpurpose>
13 </refnamediv>
14 <refsynopsisdiv>
15 <cmdsynopsis>
16 <command>nixos-option</command>
17
18 <arg>
19 <group choice='req'>
20 <arg choice='plain'><option>-r</option></arg>
21 <arg choice='plain'><option>--recursive</option></arg>
22 </group>
23 </arg>
24
25 <arg>
26 <option>-I</option> <replaceable>path</replaceable>
27 </arg>
28
29 <arg>
30 <replaceable>option.name</replaceable>
31 </arg>
32 </cmdsynopsis>
33 </refsynopsisdiv>
34 <refsection>
35 <title>Description</title>
36 <para>
37 This command evaluates the configuration specified in
38 <filename>/etc/nixos/configuration.nix</filename> and returns the properties
39 of the option name given as argument.
40 </para>
41 <para>
42 When the option name is not an option, the command prints the list of
43 attributes contained in the attribute set.
44 </para>
45 </refsection>
46 <refsection>
47 <title>Options</title>
48 <para>
49 This command accepts the following options:
50 </para>
51 <variablelist>
52 <varlistentry>
53 <term><option>-r</option></term>
54 <term><option>--recursive</option></term>
55 <listitem>
56 <para>
57 Print all the values at or below the specified path recursively.
58 </para>
59 </listitem>
60 </varlistentry>
61 <varlistentry>
62 <term>
63 <option>-I</option> <replaceable>path</replaceable>
64 </term>
65 <listitem>
66 <para>
67 This option is passed to the underlying
68 <command>nix-instantiate</command> invocation.
69 </para>
70 </listitem>
71 </varlistentry>
72 </variablelist>
73 </refsection>
74 <refsection>
75 <title>Environment</title>
76 <variablelist>
77 <varlistentry>
78 <term>
79 <envar>NIXOS_CONFIG</envar>
80 </term>
81 <listitem>
82 <para>
83 Path to the main NixOS configuration module. Defaults to
84 <filename>/etc/nixos/configuration.nix</filename>.
85 </para>
86 </listitem>
87 </varlistentry>
88 </variablelist>
89 </refsection>
90 <refsection>
91 <title>Examples</title>
92 <para>
93 Investigate option values:
94<screen><prompt>$ </prompt>nixos-option boot.loader
95This attribute set contains:
96generationsDir
97grub
98initScript
99
100<prompt>$ </prompt>nixos-option boot.loader.grub.enable
101Value:
102true
103
104Default:
105true
106
107Description:
108Whether to enable the GNU GRUB boot loader.
109
110Declared by:
111 "/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/nixos/modules/system/boot/loader/grub/grub.nix"
112
113Defined by:
114 "/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/nixos/modules/system/boot/loader/grub/grub.nix"
115</screen>
116 </para>
117 </refsection>
118 <refsection>
119 <title>Bugs</title>
120 <para>
121 The author listed in the following section is wrong. If there is any other
122 bug, please report to Nicolas Pierron.
123 </para>
124 </refsection>
125 <refsection>
126 <title>See also</title>
127 <para>
128 <citerefentry>
129 <refentrytitle>configuration.nix</refentrytitle>
130 <manvolnum>5</manvolnum>
131 </citerefentry>
132 </para>
133 </refsection>
134</refentry>