\begin{exe} {Using \textbf{chmod}}

   One can use either the octal digit
   or symbolic methods for specifying permissions when
   using \textbf{chmod}.  Let's elaborate some more
   on the symbolic method.

   It is possible to either give permissions directly,
   or add or subtract permissions.

   Try the following examples:

   \begin{cmd}
$ chmod u=r,g=w,o=x afile
$ chmod u+w,g-w,o+rw afile
$ chmod ug=rwx,o-rw afile
   \end{cmd}
   After each step do:

   \begin{cmd}
$ ls -l afile
   \end{cmd}
   to see how the permissions took, and try some variations.

\end{exe}

