<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-package-management">

<title>Package Management</title>

<para>This section describes how to add additional packages to your
system.  NixOS has two distinct styles of package management:

<itemizedlist>

  <listitem><para><emphasis>Declarative</emphasis>, where you declare
  what packages you want in your
  <filename>configuration.nix</filename>.  Every time you run
  <command>nixos-rebuild</command>, NixOS will ensure that you get a
  consistent set of binaries corresponding to your
  specification.</para></listitem>

  <listitem><para><emphasis>Ad hoc</emphasis>, where you install,
  upgrade and uninstall packages via the <command>nix-env</command>
  command.  This style allows mixing packages from different Nixpkgs
  versions.  It’s the only choice for non-root
  users.</para></listitem>

</itemizedlist>

</para>

<xi:include href="declarative-packages.xml" />
<xi:include href="ad-hoc-packages.xml" />

</chapter>
