unset [ -fmv ] name ...
       Each  named  parameter  is unset.  Local parameters
       even  if unset; they appear unset within scope, but
       value will still reappear when the scope ends.

       Individual elements of associative array parameters
       by using subscript syntax on name, which should  be
       the  entire  command   prefixed   with  noglob)  to
       script from filename generation.

       If the -m flag is specified the arguments are taken
       (should   be   quoted)   and  all  parameters  with
       unset.   Note  that this cannot be used when unset-
       array  elements, as the subscript will  be  treated
       pattern.

       The  -v flag specifies that name refers to  parame-
       the default behaviour.

       unset -f is equivalent to unfunction.
