     cd [ arg ]
     cd old new
     cd +-n
          Change the  current  directory.   In  the  first  form,
          change the current directory to arg, or to the value of
          HOME if arg is not specified.  If arg is -,  change  to
          the  value  of  OLDPWD,  the  previous directory.  If a
          directory named arg is not found in the current  direc-
          tory  and  arg does not begin with a slash, search each
          component of the shell parameter cdpath.  If the option
          CDABLEVARS  is  set,  and  a parameter named arg exists
          whose value begins with a slash, treat its value as the
          directory.

          The second form of cd substitutes the  string  new  for
          the  string  old  in the name of the current directory,
          and tries to change to this new directory.

          The third form of cd is equivalent to popd.

     chdir
          Same as cd.
