cd [ -sLP ] [ arg ]
cd [ -sLP ] old new
cd [ -sLP ] {+|-}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 CDABLE VARS is
       set, and a parameter named arg exists  whose  value
       begins  with a slash, treat its value as the direc-
       tory.

       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 extracts an entry from the
       directory stack, and changes to that directory.  An
       argument  of the form `+n' identifies a stack entry
       by counting from the left of the list shown by  the
       dirs  command,  starting with zero.  An argument of
       the form  `-n'  counts  from  the  right.   If  the
       PUSHD MINUS  option is set, the meanings of `+' and
       `-' in this context are swapped.

       If the -s  option  is  specified,  cd  will  refuse
       change  the currect directory if the given pathname

       contains symlinks.  If the -P option  is  given  or
       the  CHASE LINKS  option is set, symbolic links are
       resolved to their true values.  If the -L option is
       given symbolic links are followed regardless of the
       state of the CHASE LINKS option.

chdir  Same as cd.
