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 arg begins with a slash, attempt to change to  the
       director given by arg.

       If  arg  does  not  begin with a slash, the behaviour depends on
       whether  the  current  directory  `.'  occurs  in  the  list  of
       directories contained in the shell parameter cdpath.  If it does
       not, first attempt to change to the directory arg under the cur-
       rent directory, and if that fails but cdpath is set and contains
       at least one element attempt to  change  to  the  directory  arg
       under each component of cdpath in turn until successful.  If `.'
       occurs in cdpath, then cdpath is searched strictly in  order  so
       that `.' is only tried at the appropriate point.

       If  no  directory is found, 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.
