.. _sec-package-management:

Package Management
------------------

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

-

  *Declarative*, where you declare what packages you want
  in your :file:`configuration.nix`. Every time you run
  :command:`nixos-rebuild`, NixOS will ensure that you get a
  consistent set of binaries corresponding to your specification.

-

  *Ad hoc*, where you install, upgrade and uninstall
  packages via the :command:`nix-env` command. This style allows
  mixing packages from different Nixpkgs versions. It’s the only choice
  for non-root users.

.. toctree::

   declarative-packages.xml.rst

.. toctree::

   ad-hoc-packages.xml.rst