<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-install</command></refentrytitle>
  <manvolnum>8</manvolnum>
  <refmiscinfo class="source">NixOS</refmiscinfo>
  <!-- <refmiscinfo class="version"><xi:include href="version.txt" parse="text"/></refmiscinfo> -->
</refmeta>

<refnamediv>
  <refname><command>nixos-install</command></refname>
  <refpurpose>install bootloader and NixOS</refpurpose>
</refnamediv>

<refsynopsisdiv>
  <cmdsynopsis>
    <command>nixos-install</command>
    <arg>
      <arg choice='plain'><option>-I</option></arg>
      <replaceable>path</replaceable>
    </arg>
    <arg>
      <arg choice='plain'><option>--root</option></arg>
      <replaceable>root</replaceable>
    </arg>
    <arg>
      <arg choice='plain'><option>--closure</option></arg>
      <replaceable>closure</replaceable>
    </arg>
    <arg>
      <arg choice='plain'><option>--no-channel-copy</option></arg>
    </arg>
    <arg>
      <arg choice='plain'><option>--no-root-passwd</option></arg>
    </arg>
    <arg>
      <arg choice='plain'><option>--no-bootloader</option></arg>
    </arg>
    <arg>
      <group choice='req'>
        <arg choice='plain'><option>--max-jobs</option></arg>
        <arg choice='plain'><option>-j</option></arg>
      </group>
      <replaceable>number</replaceable>
    </arg>
    <arg>
      <option>--cores</option>
      <replaceable>number</replaceable>
    </arg>
    <arg>
      <option>--option</option>
      <replaceable>name</replaceable>
      <replaceable>value</replaceable>
    </arg>
    <arg>
      <arg choice='plain'><option>--show-trace</option></arg>
    </arg>
    <arg>
      <arg choice='plain'><option>--chroot</option></arg>
    </arg>
    <arg>
      <arg choice='plain'><option>--help</option></arg>
    </arg>
  </cmdsynopsis>
</refsynopsisdiv>


<refsection><title>Description</title>

<para>This command installs NixOS in the file system mounted on
<filename>/mnt</filename>, based on the NixOS configuration specified
in <filename>/mnt/etc/nixos/configuration.nix</filename>.  It performs
the following steps:

<itemizedlist>

  <listitem><para>It copies Nix and its dependencies to
  <filename>/mnt/nix/store</filename>.</para></listitem>

  <listitem><para>It runs Nix in <filename>/mnt</filename> to build
  the NixOS configuration specified in
  <filename>/mnt/etc/nixos/configuration.nix</filename>.</para></listitem>

  <listitem><para>It installs the GRUB boot loader on the device
  specified in the option <option>boot.loader.grub.device</option>
  (unless <option>--no-bootloader</option> is specified),
  and generates a GRUB configuration file that boots into the NixOS
  configuration just installed.</para></listitem>

  <listitem><para>It prompts you for a password for the root account
  (unless <option>--no-root-passwd</option> is specified).</para></listitem>

</itemizedlist>

</para>

<para>This command is idempotent: if it is interrupted or fails due to
a temporary problem (e.g. a network issue), you can safely re-run
it.</para>

</refsection>

<refsection><title>Options</title>

<para>This command accepts the following options:</para>

<variablelist>

  <varlistentry>
    <term><option>--root</option></term>
    <listitem>
      <para>Defaults to <filename>/mnt</filename>. If this option is given, treat the directory
      <replaceable>root</replaceable> as the root of the NixOS installation.
      </para>
    </listitem>
  </varlistentry>

  <varlistentry>
    <term><option>--closure</option></term>
    <listitem>
      <para>If this option is provided, <command>nixos-install</command> will install the specified closure
      rather than attempt to build one from <filename>/mnt/etc/nixos/configuration.nix</filename>.</para>

      <para>The closure must be an appropriately configured NixOS system, with boot loader and partition
      configuration that fits the target host. Such a closure is typically obtained with a command such as
      <command>nix-build -I nixos-config=./configuration.nix '&lt;nixos&gt;' -A system --no-out-link</command>
      </para>
    </listitem>
  </varlistentry>

  <varlistentry>
    <term><option>-I</option></term>
    <listitem>
      <para>Add a path to the Nix expression search path. This option may be given multiple times.
        See the NIX_PATH environment variable for information on the semantics of the Nix search path.
        Paths added through <replaceable>-I</replaceable> take precedence over NIX_PATH.</para>
    </listitem>
  </varlistentry>

  <varlistentry><term><option>--max-jobs</option></term>
    <term><option>-j</option></term>
  
    <listitem><para>Sets the maximum number of build jobs that Nix will
    perform in parallel to the specified number. The default is <literal>1</literal>.
    A higher value is useful on SMP systems or to exploit I/O latency.</para></listitem>
  
  </varlistentry>
  
  
  <varlistentry><term><option>--cores</option></term>
  
    <listitem><para>Sets the value of the <envar>NIX_BUILD_CORES</envar>
    environment variable in the invocation of builders.  Builders can
    use this variable at their discretion to control the maximum amount
    of parallelism.  For instance, in Nixpkgs, if the derivation
    attribute <varname>enableParallelBuilding</varname> is set to
    <literal>true</literal>, the builder passes the
    <option>-j<replaceable>N</replaceable></option> flag to GNU Make.
    The value <literal>0</literal> means that the builder should use all
    available CPU cores in the system.</para></listitem>
  
  </varlistentry>

  <varlistentry><term><option>--option</option> <replaceable>name</replaceable> <replaceable>value</replaceable></term>

    <listitem><para>Set the Nix configuration option
    <replaceable>name</replaceable> to <replaceable>value</replaceable>.</para></listitem>

  </varlistentry>

  <varlistentry>
    <term><option>--show-trace</option></term>
    <listitem>
      <para>Causes Nix to print out a stack trace in case of Nix expression evaluation errors.</para>
    </listitem>
  </varlistentry>

  <varlistentry>
    <term><option>--chroot</option></term>
    <listitem>
      <para>Chroot into given installation. Any additional arguments passed are going to be executed inside the chroot.
      </para>
    </listitem>
  </varlistentry>

  <varlistentry>
    <term><option>--help</option></term>
    <listitem>
      <para>Synonym for <command>man nixos-install</command>.</para>
    </listitem>
  </varlistentry>

</variablelist>

</refsection>


<refsection><title>Examples</title>

<para>A typical NixOS installation is done by creating and mounting a
file system on <filename>/mnt</filename>, generating a NixOS
configuration in
<filename>/mnt/etc/nixos/configuration.nix</filename>, and running
<command>nixos-install</command>.  For instance, if we want to install
NixOS on an <literal>ext4</literal> file system created in
<filename>/dev/sda1</filename>:

<screen>
$ mkfs.ext4 /dev/sda1
$ mount /dev/sda1 /mnt
$ nixos-generate-config --root /mnt
$ # edit /mnt/etc/nixos/configuration.nix
$ nixos-install
$ reboot
</screen>

</para>

</refsection>

</refentry>
