       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  directory  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 direc-
              tory.

              The third form of cd is equivalent to popd.

       chdir  Same as cd.
