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.  Otherwise, 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 no directory is found
       and the option CDABLE VARS is set, and a  parameter
       named  arg  exists whose value begins with a slash,
       treat its value as the directory.   In  that  case,
       the  parameter is added to the named directory hash
       table.

       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 refuses to change
       the  current  directory  if the given pathname con
       tains 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.
