public boolean execute(){			
		//execute master_node. waiting for input and choose a slave to do the command.
		Scanner sca = new Scanner(System.in);
		
		try {
			String local = InetAddress.getLocalHost().getHostAddress();
			System.out.println(local);
		} catch (UnknownHostException e) {
			e.printStackTrace();
		}
		
		while(true){
			System.out.print("==>");
			String command_line = sca.nextLine();	
			
			String[] commandAndArg = Parse.parseCommand(command_line);
			if(commandAndArg ==  null){
				System.out.println("Command not supported or in wrong format");
				continue;
			}
			else if(commandAndArg[0].equals("ps"))				// show all the processes
				procTable.printProcList();
			else if(commandAndArg[0].equals("quit"))			// quit system
				System.exit(1);
			else if(commandAndArg[0].equals("kill"))			// kill a process
				procKill(commandAndArg);	
			else if(commandAndArg[0].equals("ws")){				//workload show
				printSlaves();
			}
			else if(commandAndArg[0].equals("transfer")){		// transfer a process to another node
				String pidAndName = getPidAndName(commandAndArg);
				System.out.println("transfer pid is:"+pidAndName);
				procTransfer(pidAndName, commandAndArg[commandAndArg.length - 1]);
			}
			else
				this.procCommands(commandAndArg);
		}
	}