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 directory.

       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 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.
