\section{/tmp}
\begin{frame}
   {/tmp}

   \begin{itemize}
      \item Used to store temporary files
      \item Assume that any files stored here are
      subject to deletion
      \begin{itemize}
         \item \textbf{Ubuntu} wipes \filelink{/tmp} on every
         system reboot!
      \end{itemize}
      \item Beware of systems (such as \textbf{Fedora})
      that mount \filelink{/tmp} as a pseudo-filesystem
      in memory.
      \begin{itemize}
         \item
         Convert to a real filesystem on storage with:
         \begin{cmd}
$ sudo systemctl mask tmp.mount            
          \end{cmd}
         and a reboot
      \end{itemize}
   \end{itemize}

\end{frame}

\cprotect\note{

   Used to store temporary files, and
   can be accessed by any user or application. However,
   any files on \filelink{/tmp} can not be depended on
   to stay around for a long time:
   \begin{itemize}
      \item
      Some distributions run automated \textbf{cron}
      jobs which remove any files older than 10 days
      typically, unless the purge scripts have been
      modified to exclude them.
      \item
      Some distributions remove the contents of
      \filelink{/tmp} with every reboot.  This has been
      the \textbf{Ubuntu} policy.
      \item
      Some modern distributions utilize a virtual
      filesystem using the \filelink{/tmp} directory
      only as a mount point for a \textbf{ram disk}
      using the \textbf{tmpfs} filesystem.  This is the
      default policy on \textbf{Fedora} systems.
      When the system reboots, all information is
      thereby lost; \filelink{/tmp} is indeed temporary!
   \end{itemize}

   In the last case, one must avoid creating large
   files on \filelink{/tmp}; they will actually occupy
   space in memory rather than disk, and it is easy to
   harm or crash the system through memory exhaustion.
   While the guideline is for applications to avoid
   putting large files in \filelink{/tmp}, there are
   plenty of applications that violate this policy and
   which make large temporary files in \filelink{/tmp};
   even if it is possible to put them somewhere else
   (perhaps by specifying an environment variable),
   many users are not aware of how to configure this
   and all users have access to \filelink{/tmp}.

   This policy can be canceled on systems using
   \textbf{systemd} such as \textbf{Feodra}, by issuing
   the command:
   \begin{cmd}
$ sudo systemctl mask tmp.mount
   \end{cmd}
   followed by a system reboot.

}

