###############################
  A brief introduction to Linux
###############################

If you're already familiar with UNIX, you can just skim or skip these topics.

You can spend a lifetime learning UNIX; I've worked with it since
1993 and I'm still learning something new every day. The
commands in the following topics, limited to what you'll need for
:ref:`the basics <the basics>`, barely scratch the surface.

.. toctree::
   :maxdepth: 1

   Directories.md
   OtherCommands.md
   CommandLineTricks.md

.. admonition:: Better UNIX references
   :class: note

   Either of these two sites offer a good introduction to UNIX:[#f3]_

   * `UNIX Tutorial for Beginners <http://www.ee.surrey.ac.uk/Teaching/Unix/>`_

   * `Learn UNIX <https://www.tutorialspoint.com/unix/index.htm>`_

.. figure:: https://imgs.xkcd.com/comics/cautionary.png
   :align: center
   :alt: xkcd cautionary

   <http://xkcd.com/456> by Randall Munroe

.. rubric:: Footnotes

.. [#f3] For the purposes of this tutorial, "Linux" and "UNIX" are the same
    thing. Systems administrators know that Linux and Mac OS Darwin are
    varieties of UNIX, but you're not here to be a sysadmin... at least
    not for today.