\section{/dev}
\begin{frame}
   {/dev}
   \begin{multicols}{2}
      \begin{itemize}
         \item Character and Block \textbf{device nodes}, or files
         \item Essential for proper system operation
         \item Modern systems manage device files
         automatically via \textbf{udev}
         \item On ancient systems (or embedded devices), can
         be created by \textbf{MAKEDEV} or \textbf{mknod}
         at install or at any other time as needed
      \end{itemize}
      \begin{figure}[H]
         \includegraphics[height=3.3in]{IMAGES/device_node_large}
         \caption{Device Nodes}
      \end{figure}
   \end{multicols}
\end{frame}

\cprotect\note{

   This directory contains \textbf{special device files}
   (also known as \textbf{device nodes}) which represent
   devices built into or connected to the system.  These special
   files are essential for the system to function properly.
   Such device files represent \textbf{character}
   (byte-stream) and \textbf{block} I/O devices;
   \textbf{network} devices do not have devices nodes in
   \textbf{Linux} and are instead referenced by name, such as
   \texttt{eth1} or \texttt{wlan0}.

   \begin{figure}[H]
      \includegraphics[width=4.0in]{IMAGES/lsdev}
      \caption{/dev Directory}
   \end{figure}
   \vspace{-30pt}

   All modern \textbf{Linux} distributions use the
   \textbf{udev} system, which creates nodes in
   \filelink{/dev} only as needed when devices are found,
   If you were to look at the \filelink{/dev} directory on
   an unmounted filesystem, you would find it empty.
   %%   directory; upon boot a virtual filesystem is created and
   %%   mounted at \filelink{/dev} and then populated with
   %%   devices nodes as \textbf{udev} requires.  Embedded
   %%   \textbf{Linux} systems (which are not being discussed
   %%   much in this course) may have fixed device nodes and not
   %%   use \textbf{udev} or use an alternative such as
   %%   \textbf{mdev}.
}



