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+<refentry xmlns="http://docbook.org/ns/docbook"
+          xmlns:xlink="http://www.w3.org/1999/xlink"
+          xmlns:xi="http://www.w3.org/2001/XInclude">
+ <refmeta>
+  <refentrytitle><command>nixos-version</command>
+  </refentrytitle><manvolnum>8</manvolnum>
+  <refmiscinfo class="source">NixOS</refmiscinfo>
+ </refmeta>
+ <refnamediv>
+  <refname><command>nixos-version</command></refname>
+  <refpurpose>show the NixOS version</refpurpose>
+ </refnamediv>
+ <refsynopsisdiv>
+  <cmdsynopsis>
+   <command>nixos-version</command>
+   <arg>
+    <option>--hash</option>
+   </arg>
+
+   <arg>
+    <option>--revision</option>
+   </arg>
+
+   <arg>
+    <option>--json</option>
+   </arg>
+
+  </cmdsynopsis>
+ </refsynopsisdiv>
+
+ <refsection>
+  <title>Description</title>
+  <para>
+   This command shows the version of the currently active NixOS configuration.
+   For example:
+<screen><prompt>$ </prompt>nixos-version
+16.03.1011.6317da4 (Emu)
+</screen>
+   The version consists of the following elements:
+   <variablelist>
+    <varlistentry>
+     <term>
+      <literal>16.03</literal>
+     </term>
+     <listitem>
+      <para>
+       The NixOS release, indicating the year and month in which it was
+       released (e.g. March 2016).
+      </para>
+     </listitem>
+    </varlistentry>
+    <varlistentry>
+     <term>
+      <literal>1011</literal>
+     </term>
+     <listitem>
+      <para>
+       The number of commits in the Nixpkgs Git repository between the start of
+       the release branch and the commit from which this version was built.
+       This ensures that NixOS versions are monotonically increasing. It is
+       <literal>git</literal> when the current NixOS configuration was built
+       from a checkout of the Nixpkgs Git repository rather than from a NixOS
+       channel.
+      </para>
+     </listitem>
+    </varlistentry>
+    <varlistentry>
+     <term>
+      <literal>6317da4</literal>
+     </term>
+     <listitem>
+      <para>
+       The first 7 characters of the commit in the Nixpkgs Git repository from
+       which this version was built.
+      </para>
+     </listitem>
+    </varlistentry>
+    <varlistentry>
+     <term>
+      <literal>Emu</literal>
+     </term>
+     <listitem>
+      <para>
+       The code name of the NixOS release. The first letter of the code name
+       indicates that this is the N'th stable NixOS release; for example, Emu
+       is the fifth release.
+      </para>
+     </listitem>
+    </varlistentry>
+   </variablelist>
+  </para>
+ </refsection>
+
+ <refsection>
+  <title>Options</title>
+
+  <para>
+   This command accepts the following options:
+  </para>
+
+  <variablelist>
+
+   <varlistentry>
+    <term>
+     <option>--hash</option>
+    </term>
+    <term>
+     <option>--revision</option>
+    </term>
+    <listitem>
+     <para>
+      Show the full SHA1 hash of the Git commit from which this configuration
+      was built, e.g.
+<screen><prompt>$ </prompt>nixos-version --hash
+6317da40006f6bc2480c6781999c52d88dde2acf
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <option>--json</option>
+    </term>
+    <listitem>
+     <para>
+      Print a JSON representation of the versions of NixOS and the
+      top-level configuration flake.
+     </para>
+    </listitem>
+   </varlistentry>
+
+  </variablelist>
+
+ </refsection>
+
+</refentry>