unsetopt [ {+|-}options | {+|-}o option_name ] [ name ... ]
       Unset the options for the shell.  All options  specified  either
       with  flags or by name are unset.  If no arguments are supplied,
       the names of all options currently unset are printed.  If the -m
       flag  is given the arguments are taken as patterns (which should
       be quoted to preserve them from being interpreted as  glob  pat-
       terns),  and  all options with names matching these patterns are
       unset.
