.. highlight:: console

.. role:: bash(code)
   :language: bash
   :class: highlight

Moving around the file system
-----------------------------

..	
	%\clearpage
	\timefornotes{File system structure}{
	  \begin{itemize}
	  \item Strictly rooted tree --- unlike Windows \kbd{A:}, \kbd{C:}, \kbd{D:}
	  \item Brilliant abstraction: \kbd{/dev}, \kbd{/proc}\dots
	  \item Navigation in tree, with convenience UI shortcuts, e.g. the
	  Desktop is one specific directory in the tree
	  \item Complications: hard and soft links, FIFOs, etc. --- for later.
	  \end{itemize}
	}

ls
~~
	
Let's move on to something useful... :command:`ls` will *list* the contents of the directory you're currently in. Find out what command line switches it supports. Our favourites are :option:`-a -l -t -r -h -S -1` and :option:`-o`.

Several switches can be combined behind one :option:`-` like this::

	$ ls -lrt

The argument :option:`--color` is a very
useful thing to have enabled by default (see aliases, later.)

pwd
~~~

Use :command:`pwd` to find out which directory you're currently looking
at. On UNIX systems, the full :dfn:`path` to a file starts from the
:dfn:`root directory` :kbd:`/`, followed by the nested directories up
to the one the file lives in. Paths will work with any command whenever a filename is expected.

cd
~~

Moving between directories is done with :command:`cd` followed by a
directory name. Some names are special: 

- :kbd:`~` is your home directory
- :kbd:`.` is the current directory
- :kbd:`..` is the parent directory (one step closer to :kbd:`/`)

You can use these anywhere inside a path, but they're of course 
most useful at the beginning of the path.

Now  move around your file system. Keep track of where you are with :command:`pwd` and use :command:`ls` to see what files are here.

Another shortcut, :bash:`cd -`, takes you back to the previous directory you were in. Why is this not the same as :bash:`cd ..`?
	
What happens when you type :bash:`cd` without an argument?

mkdir
~~~~~

You can create new directories with :command:`mkdir` followed by the name of the directory to create. The following exercises are best done in
a new directory, so we will create one in your home directory and \cmd{cd} into it::

	$ cd ~
	$ mkdir NewDirectoryThatWillBeUsedForTheExercises
	$ cd NewDirectoryThatWillBeUsedForTheExercises

Other names are fine, too, of course. This is a good time to explore :dfn:`tab completion` --- try typing some starting characters of a command or file you know to exist, then press the tab key (maybe twice). :command:`bash` will fill in the rest of the name if possible.