nixpkgs/nixos/doc/manual/installation/installing.xml

<chapter xmlns="http://docbook.org/ns/docbook"
            xmlns:xlink="http://www.w3.org/1999/xlink"
            xmlns:xi="http://www.w3.org/2001/XInclude"
            version="5.0"
            xml:id="sec-installation">

<title>Installing NixOS</title>

<para>NixOS can be installed on BIOS or UEFI systems.  The procedure
for a UEFI installation is by and large the same as a BIOS installation. The differences are mentioned in the steps that follow.</para>

<orderedlist>

  <listitem><para>Boot from the CD.</para>
    <variablelist>
      <varlistentry><term>UEFI systems</term>
      <listitem><para>You should boot the live CD in UEFI mode
  (consult your specific hardware's documentation for instructions).
  You may find the <link xlink:href="http://www.rodsbooks.com/refind">rEFInd boot
  manager</link> useful.</para></listitem></varlistentry></variablelist></listitem>

  <listitem><para>The CD contains a basic NixOS installation.  (It
  also contains Memtest86+, useful if you want to test new hardware).
  When it’s finished booting, it should have detected most of your
  hardware.</para></listitem>

  <listitem><para>The NixOS manual is available on virtual console 8
  (press Alt+F8 to access) or by running <command>nixos-help</command>.
  </para></listitem>

  <listitem><para>You get logged in as <literal>root</literal>
  (with empty password).</para></listitem>

  <listitem><para>If you downloaded the graphical ISO image, you can
  run <command>systemctl start display-manager</command> to start KDE. If you
  want to continue on the terminal, you can use
  <command>loadkeys</command> to switch to your preferred keyboard layout.
  (We even provide neo2 via <command>loadkeys de neo</command>!)</para></listitem>

  <listitem><para>The boot process should have brought up networking (check
  <command>ip a</command>).  Networking is necessary for the
  installer, since it will download lots of stuff (such as source
  tarballs or Nixpkgs channel binaries).  It’s best if you have a DHCP
  server on your network. Otherwise configure networking manually
  using <command>ifconfig</command>.</para>
  <para>To manually configure the network on the graphical installer,
  first disable network-manager with
  <command>systemctl stop network-manager</command>.</para>
  <para>To manually configure the wifi on the minimal installer, run
  <command>wpa_supplicant -B -i interface -c &lt;(wpa_passphrase 'SSID' 'key')</command>.</para></listitem>


  <listitem><para>If you would like to continue the installation from a different
  machine you need to activate the SSH daemon via <literal>systemctl start sshd</literal>.
  In order to be able to login you also need to set a password for
  <literal>root</literal> using <literal>passwd</literal>.</para></listitem>

  <listitem><para>The NixOS installer doesn’t do any partitioning or
  formatting yet, so you need to do that yourself.  Use the following
  commands:

  <itemizedlist>

    <listitem><para>For partitioning:
    <command>fdisk</command>.
<screen>
# fdisk /dev/sda # <lineannotation>(or whatever device you want to install on)</lineannotation>
-- for UEFI systems only
> n      # <lineannotation>(create a new partition for /boot)</lineannotation>
> 3      # <lineannotation>(make it a partition number 3)</lineannotation>
>        # <lineannotation>(press enter to accept the default)</lineannotation>
> +512M  # <lineannotation>(the size of the UEFI boot partition)</lineannotation>
> t      # <lineannotation>(change the partition type ...)</lineannotation>
> 3      # <lineannotation>(... of the boot partition ...)</lineannotation>
> 1      # <lineannotation>(... to 'UEFI System')</lineannotation>
-- for BIOS or UEFI systems
> n      # <lineannotation>(create a new partition for /swap)</lineannotation>
> 2      # <lineannotation>(make it a partition number 2)</lineannotation>
>        # <lineannotation>(press enter to accept the default)</lineannotation>
> +8G    # <lineannotation>(the size of the swap partition, set to whatever you like)</lineannotation>
> n      # <lineannotation>(create a new partition for /)</lineannotation>
> 1      # <lineannotation>(make it a partition number 1)</lineannotation>
>        # <lineannotation>(press enter to accept the default)</lineannotation>
>        # <lineannotation>(press enter to accept the default and use the rest of the remaining space)</lineannotation>
> a      # <lineannotation>(make the partition bootable)</lineannotation>
> x      # <lineannotation>(enter expert mode)</lineannotation>
> f      # <lineannotation>(fix up the partition ordering)</lineannotation>
> r      # <lineannotation>(exit expert mode)</lineannotation>
> w      # <lineannotation>(write the partition table to disk and exit)</lineannotation></screen></para></listitem>

    <listitem><para>For initialising Ext4 partitions:
    <command>mkfs.ext4</command>.  It is recommended that you assign a
    unique symbolic label to the file system using the option
    <option>-L <replaceable>label</replaceable></option>, since this
    makes the file system configuration independent from device
    changes.  For example:

<screen>
# mkfs.ext4 -L nixos /dev/sda1</screen>

    </para></listitem>

    <listitem><para>For creating swap partitions:
    <command>mkswap</command>.  Again it’s recommended to assign a
    label to the swap partition: <option>-L
    <replaceable>label</replaceable></option>. For example:

<screen>
# mkswap -L swap /dev/sda2</screen>

    </para></listitem>

    <listitem>
    <variablelist>
      <varlistentry><term>UEFI systems</term>
      <listitem><para>For creating boot partitions:
    <command>mkfs.fat</command>.  Again it’s recommended to assign a
    label to the boot partition: <option>-n
    <replaceable>label</replaceable></option>. For example:

<screen>
# mkfs.fat -F 32 -n boot /dev/sda3</screen>

    </para></listitem></varlistentry></variablelist></listitem>

    <listitem><para>For creating LVM volumes, the LVM commands, e.g.,
    <command>pvcreate</command>, <command>vgcreate</command>, and
    <command>lvcreate</command>.</para></listitem>

    <listitem><para>For creating software RAID devices, use
    <command>mdadm</command>.</para></listitem>

  </itemizedlist>

  </para></listitem>

  <listitem><para>Mount the target file system on which NixOS should
  be installed on <filename>/mnt</filename>, e.g.

<screen>
# mount /dev/disk/by-label/nixos /mnt
</screen>

  </para></listitem>

  <listitem>
    <variablelist>
      <varlistentry><term>UEFI systems</term>
      <listitem><para>Mount the boot file system on <filename>/mnt/boot</filename>, e.g.

<screen>
# mkdir -p /mnt/boot
# mount /dev/disk/by-label/boot /mnt/boot
</screen>

  </para></listitem></varlistentry></variablelist></listitem>

  <listitem><para>If your machine has a limited amount of memory, you
  may want to activate swap devices now (<command>swapon
  <replaceable>device</replaceable></command>).  The installer (or
  rather, the build actions that it may spawn) may need quite a bit of
  RAM, depending on your configuration.

<screen>
# swapon /dev/sda2</screen>

  </para></listitem>

  <listitem>

    <para>You now need to create a file
    <filename>/mnt/etc/nixos/configuration.nix</filename> that
    specifies the intended configuration of the system.  This is
    because NixOS has a <emphasis>declarative</emphasis> configuration
    model: you create or edit a description of the desired
    configuration of your system, and then NixOS takes care of making
    it happen.  The syntax of the NixOS configuration file is
    described in <xref linkend="sec-configuration-syntax"/>, while a
    list of available configuration options appears in <xref
    linkend="ch-options"/>.  A minimal example is shown in <xref
    linkend="ex-config"/>.</para>

    <para>The command <command>nixos-generate-config</command> can
    generate an initial configuration file for you:

<screen>
# nixos-generate-config --root /mnt</screen>

    You should then edit
    <filename>/mnt/etc/nixos/configuration.nix</filename> to suit your
    needs:

<screen>
# nano /mnt/etc/nixos/configuration.nix
</screen>

    If you’re using the graphical ISO image, other editors may be
    available (such as <command>vim</command>). If you have network
    access, you can also install other editors — for instance, you can
    install Emacs by running <literal>nix-env -i
    emacs</literal>.</para>

    <variablelist>

      <varlistentry><term>BIOS systems</term>
        <listitem><para>You <emphasis>must</emphasis> set the option
            <xref linkend="opt-boot.loader.grub.device"/> to specify on which disk
            the GRUB boot loader is to be installed.  Without it, NixOS cannot
            boot.</para></listitem></varlistentry>

      <varlistentry><term>UEFI systems</term>
        <listitem><para>You <emphasis>must</emphasis> set the option
            <xref linkend="opt-boot.loader.systemd-boot.enable"/> to <literal>true</literal>.
            <command>nixos-generate-config</command> should do this automatically for new
            configurations when booted in
            UEFI mode.</para>
          <para>You may want to look at the options starting with
            <option><link linkend="opt-boot.loader.efi.canTouchEfiVariables">boot.loader.efi</link></option> and
            <option><link linkend="opt-boot.loader.systemd-boot.enable">boot.loader.systemd</link></option> as well.
          </para>
        </listitem>
      </varlistentry>

    </variablelist>

    <para>If there are other operating systems running on the machine before
    installing NixOS, the
    <xref linkend="opt-boot.loader.grub.useOSProber"/> option can be set to
    <literal>true</literal> to automatically add them to the grub menu.</para>

    <para>Another critical option is <option>fileSystems</option>,
    specifying the file systems that need to be mounted by NixOS.
    However, you typically don’t need to set it yourself, because
    <command>nixos-generate-config</command> sets it automatically in
    <filename>/mnt/etc/nixos/hardware-configuration.nix</filename>
    from your currently mounted file systems.  (The configuration file
    <filename>hardware-configuration.nix</filename> is included from
    <filename>configuration.nix</filename> and will be overwritten by
    future invocations of <command>nixos-generate-config</command>;
    thus, you generally should not modify it.)</para>

    <note><para>Depending on your hardware configuration or type of
    file system, you may need to set the option
    <option>boot.initrd.kernelModules</option> to include the kernel
    modules that are necessary for mounting the root file system,
    otherwise the installed system will not be able to boot.  (If this
    happens, boot from the CD again, mount the target file system on
    <filename>/mnt</filename>, fix
    <filename>/mnt/etc/nixos/configuration.nix</filename> and rerun
    <filename>nixos-install</filename>.)  In most cases,
    <command>nixos-generate-config</command> will figure out the
    required modules.</para></note>

  </listitem>

  <listitem><para>Do the installation:

<screen>
# nixos-install</screen>

    Cross fingers.  If this fails due to a temporary problem (such as
    a network issue while downloading binaries from the NixOS binary
    cache), you can just re-run <command>nixos-install</command>.
    Otherwise, fix your <filename>configuration.nix</filename> and
    then re-run <command>nixos-install</command>.</para>

    <para>As the last step, <command>nixos-install</command> will ask
    you to set the password for the <literal>root</literal> user, e.g.

    <screen>
setting root password...
Enter new UNIX password: ***
Retype new UNIX password: ***
    </screen>

    <note>
      <para>
        To prevent the password prompt, set <code><xref linkend="opt-users.mutableUsers"/> = false;</code> in
        <filename>configuration.nix</filename>, which allows unattended installation
        necessary in automation.
      </para>
    </note>

    </para>

  </listitem>

  <listitem>
    <para>If everything went well:

      <screen>
        # reboot</screen>

  </para></listitem>

  <listitem>

    <para>You should now be able to boot into the installed NixOS. The
      GRUB boot menu shows a list of <emphasis>available
        configurations</emphasis> (initially just one). Every time you
      change the NixOS configuration (see <link
        linkend="sec-changing-config">Changing Configuration</link> ), a
      new item is added to the menu. This allows you to easily roll back
      to a previous configuration if something goes wrong.</para>

    <para>You should log in and change the <literal>root</literal>
    password with <command>passwd</command>.</para>

    <para>You’ll probably want to create some user accounts as well,
    which can be done with <command>useradd</command>:

<screen>
$ useradd -c 'Eelco Dolstra' -m eelco
$ passwd eelco</screen>

    </para>

    <para>You may also want to install some software.  For instance,

<screen>
$ nix-env -qa \*</screen>

    shows what packages are available, and

<screen>
$ nix-env -i w3m</screen>

    install the <literal>w3m</literal> browser.</para>

  </listitem>

</orderedlist>

<para>To summarise, <xref linkend="ex-install-sequence" /> shows a
typical sequence of commands for installing NixOS on an empty hard
drive (here <filename>/dev/sda</filename>).  <xref linkend="ex-config"
/> shows a corresponding configuration Nix expression.</para>

<example xml:id='ex-install-sequence'><title>Commands for Installing NixOS on <filename>/dev/sda</filename></title>
<screen>
# fdisk /dev/sda # <lineannotation>(or whatever device you want to install on)</lineannotation>
-- for UEFI systems only
> n      # <lineannotation>(create a new partition for /boot)</lineannotation>
> 3      # <lineannotation>(make it a partition number 3)</lineannotation>
>        # <lineannotation>(press enter to accept the default)</lineannotation>
> +512M  # <lineannotation>(the size of the UEFI boot partition)</lineannotation>
> t      # <lineannotation>(change the partition type ...)</lineannotation>
> 3      # <lineannotation>(... of the boot partition ...)</lineannotation>
> 1      # <lineannotation>(... to 'UEFI System')</lineannotation>
-- for BIOS or UEFI systems
> n      # <lineannotation>(create a new partition for /swap)</lineannotation>
> 2      # <lineannotation>(make it a partition number 2)</lineannotation>
>        # <lineannotation>(press enter to accept the default)</lineannotation>
> +8G    # <lineannotation>(the size of the swap partition)</lineannotation>
> n      # <lineannotation>(create a new partition for /)</lineannotation>
> 1      # <lineannotation>(make it a partition number 1)</lineannotation>
>        # <lineannotation>(press enter to accept the default)</lineannotation>
>        # <lineannotation>(press enter to accept the default and use the rest of the remaining space)</lineannotation>
> a      # <lineannotation>(make the partition bootable)</lineannotation>
> x      # <lineannotation>(enter expert mode)</lineannotation>
> f      # <lineannotation>(fix up the partition ordering)</lineannotation>
> r      # <lineannotation>(exit expert mode)</lineannotation>
> w      # <lineannotation>(write the partition table to disk and exit)</lineannotation>
# mkfs.ext4 -L nixos /dev/sda1
# mkswap -L swap /dev/sda2
# swapon /dev/sda2
# mkfs.fat -F 32 -n boot /dev/sda3        # <lineannotation>(for UEFI systems only)</lineannotation>
# mount /dev/disk/by-label/nixos /mnt
# mkdir -p /mnt/boot                      # <lineannotation>(for UEFI systems only)</lineannotation>
# mount /dev/disk/by-label/boot /mnt/boot # <lineannotation>(for UEFI systems only)</lineannotation>
# nixos-generate-config --root /mnt
# nano /mnt/etc/nixos/configuration.nix
# nixos-install
# reboot</screen>
</example>

<example xml:id='ex-config'><title>NixOS Configuration</title>
  <screen>
{ config, pkgs, ... }: {
  imports = [
    # Include the results of the hardware scan.
    ./hardware-configuration.nix
  ];

  <xref linkend="opt-boot.loader.grub.device"/> = "/dev/sda";   # <lineannotation>(for BIOS systems only)</lineannotation>
  <xref linkend="opt-boot.loader.systemd-boot.enable"/> = true; # <lineannotation>(for UEFI systems only)</lineannotation>

  # Note: setting fileSystems is generally not
  # necessary, since nixos-generate-config figures them out
  # automatically in hardware-configuration.nix.
  #<link linkend="opt-fileSystems._name__.device">fileSystems."/".device</link> = "/dev/disk/by-label/nixos";

  # Enable the OpenSSH server.
  services.sshd.enable = true;
}
  </screen>
</example>

<xi:include href="installing-usb.xml" />
<xi:include href="installing-pxe.xml" />
<xi:include href="installing-virtualbox-guest.xml" />
<xi:include href="installing-from-other-distro.xml" />

</chapter>