The shell sets two options for GrepCommand (and child class EgrepCommand) - numThreads and table. numThreads uses the flag "t" while table uses an enum which is "t". Not only that, but GrepCommand extends ScanCommand (and also calls the super.getOptions) which also sets the table Option. The strange part is that num-threads takes precedence even though it's sandwiched within calls. This may call for a check of all Shell Commands to make sure this isn't done elsewhere. We may want to create of a master index of Shell options to make sure we don't have this collision space again.