@Override
	public boolean execute(CommandSender sender, String[] args) {
		if(!(sender instanceof CommandSender)
				|| (sender instanceof Player && !sender.isOp())) {
			sender.sendMessage("You don't have permission to perform this command");
			return true;
		}
		
		Collection<Group> groups = groupManager.getAllGroups();
		if(groups.size() == 0) {
			sender.sendMessage("No data");
			return true;
		}
		
		for(Group group : groups) {
			sender.sendMessage(group.getName());
		}
		
		return true;
	}