[ Python 常見問題 ] Interactive input/output using python

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Question 
I have a program that interacts with the user (acts like a shell), and I want to run it using python subprocess module interactively. That means, I want the possibility to write to stdin and immediately get the output from stdout. I tried many solutions offered here, but none of them seems to work for my needs. 

The code I've written based on Running an interactive command from within python: 

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1. import Queue  
2. import threading  
3. import subprocess  
4.   
5. def enqueue_output(out, queue):  
6.     for line in iter(out.readline, b''):  
7.         queue.put(line)  
8.     out.close()  
9.   
10. def getOutput(outQueue):  
11.     outStr = ''  
12.     try:  
13.         while True: #Adds output from the Queue until it is empty  
14.             outStr+=outQueue.get_nowait()  
15.   
16.     except Queue.Empty:  
17.         return outStr  
18.   
19. p = subprocess.Popen("./a.out", stdin=subprocess.PIPE, stout=subprocess.PIPE, stderr=subprocess.PIPE, bufsize = 1)  
20. #p = subprocess.Popen("./a.out", stdin=subprocess.PIPE, stout=subprocess.PIPE, stderr=subprocess.PIPE, shell=False, universal_newlines=True)  
21.   
22. outQueue = Queue()  
23. errQueue = Queue()  
24.   
25. outThread = Thread(target=enqueue_output, args=(p.stdout, outQueue))  
26. errThread = Thread(target=enqueue_output, args=(p.stderr, errQueue))  
27.   
28. outThread.daemon = True  
29. errThread.daemon = True  
30.   
31. outThread.start()  
32. errThread.start()  
33.   
34. p.stdin.write("1\n")  
35. p.stdin.flush()  
36. errors = getOutput(errQueue)  
37. output = getOutput(outQueue)  
38.   
39. p.stdin.write("5\n")  
40. p.stdin.flush()  
41. erros = getOutput(errQueue)  
42. output = getOutput(outQueue)  

The problem is that the queue remains empty, as if there is no output. Only if I write to stdin all the input that the program needs to execute and terminate, then I get the output (which is not what I want ). Is there any way to do what I want to do? 

How-To 
Second try: I tried this solution and it works for me. Firstly, a testing shell to echo with input line: 
- test.sh 

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1. #!/bin/sh  
2. while read LINE; do  
3.     echo "OUT> $LINE"  
4.     if [ "$LINE" == "bye" ]; then  
5.         break  
6.     fi  
7. done  

Usage: 

# ./test.sh
test line1
OUT> test line1
test line2
OUT> test line2
bye // Exit the interactive shell
OUT> bye

Then we can use python code to run this interactive shell: 
- test.py 

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1. from subprocess import Popen, PIPE  
2. import time  
3.   
4.   
5. class CmdInteractor:  
6.     def __init__(self, cmd, tmp_file = "tmpout"):  
7.         self.cmd = cmd  
8.         self.fw = open(tmp_file, "wb")  
9.         self.fr = fr = open(tmp_file, "r")  
10.         self.p = Popen(cmd, shell=True, stdin = PIPE, stdout = self.fw, stderr = self.fw)  
11.   
12.     def sendline(self, msg):  
13.         self.p.stdin.write(("%s\n" % (msg)).encode()); self.p.stdin.flush()  
14.   
15.     def readline(self, timeout=10):  
16.         r'''  
17.         Read one line from stdout  
18.   
19.         @param timeouot:  
20.             Timeout in second  
21.         '''  
22.         out = self.fr.readline()  
23.         wi = 0  
24.         while out is None or out == '':  
25.             wi = wi + 1  
26.             if wi > 10:  
27.                 raise Exception('Timeout in reading line from output!')  
28.             time.sleep(1)  
29.             out = self.fr.readline()  
30.         return out.rstrip()  
31.   
32.     def __del__(self):  
33.         self.fw.close()  
34.         self.fr.close()  
35.         self.p.terminate()  
36.   
37. ci = CmdInteractor('./test.sh')  
38. ci.sendline('Test')  
39. print("Read: %s" % (ci.readline()))  
40. ci.sendline('Hello')  
41. print("Read: %s" % (ci.readline()))  
42. print("\t[Info] Say bye!")  
43. ci.sendline('bye')  
44. print("Read: %s" % (ci.readline()))  

Execution out: 

# ./test.py
Read: OUT> Test
Read: OUT> Hello
[Info] Say bye!
Read: OUT> bye

Supplement 
* Running an interactive command from within python 
* Python std library - subprocess — Subprocess management