OptArg:String Is set to the argument of an option, if the option needs
one.
Optind:Longint Is the index of the current paramstr(). When
all options have been processed, optind is the index of the first
non-option parameter. This is a read-only variable. Note that it can become
equal to paramcount+1
OptErr:Boolean Indicates whether getopt() prints error
messages.
OptOpt:Char In case of an error, contains the character causing the
error.