在程序运行时按下任意键时停止 python 程序

Question

I recently got to know about the python module signal. With that, we can capture a SIGINT and do what we want after capturing it. I used it as below. In that case I am just using SIGINT to print that program is going to be stopped and stop the program.

import signal  
import os
import time

def signalHandler(signalnumb, frame):  
    print("Signal Number:", signalnumb, " Frame: ", frame)
    print('Exiting the program...')
    os._exit(0)
 
signal.signal(signal.SIGINT, signalHandler)
 
c=0
# Loop infinite times using the while(1) which is always true
while 1:
    print(c)
    #sleep for 1 seconds using the sleep() function in time 
    time.sleep(1)
    c=c+1

Now I want to give any signal from keyboard(for example pressing 'q') and as soon as signal was recieved, the python program should be stopped. Has anyone got some experience on how to do that? Any other method rather than using signal module (for example using multithreading) is accepted.

Edit1- Later I tried to use pynput module as suggested in one of a similar kind of question. For sure I have done a mistake. It doesn't work as I expected. It means with a key press, I couldn't stop the for loop from running.

from pynput import keyboard
import time

def on_press(key):
    for i in range(100):
        print(i)
        time.sleep(1)
        if key == keyboard.Key.esc:
            return False  # stop listener
        try:
            k = key.char  # single-char keys
        except:
            k = key.name  # other keys
        if k in ['1', '2', 'left', 'right']:  # keys of interest
            # self.keys.append(k)  # store it in global-like variable
            print('Key pressed: ' + k)
            return False  # stop listener; remove this if want more keys

listener = keyboard.Listener(on_press=on_press)
listener.start()  # start to listen on a separate thread
listener.join()  # remove if main thread is polling self.keyspython

Can someone point out how to do it using pynput in correct way?

Answer 1

This was my original implementation:

a = input('Press a key to exit')
if a:
    exit(0)

However, it seems that you need a piece of code that will allow for any key to be clicked and immediately exit out of the program, without hitting enter afterwards. This may be a better way to do that:

import readchar
print("Press Any Key To Exit")
k = readchar.readchar()

Hope this helps!

Answer 2

After carefully understanding about the threads and pynput module, I managed to stop a for loop (or any program which runs as a separate thread) using a key press callback.

from pynput import keyboard
import os
import threading
import time

loop_running = False

def on_press(key):
    print(dir(key))
    global loop_running
    #if key == keyboard.Key.delete and not loop_running:
    if ('char' in dir(key)) and (key.char == 's') and (not loop_running):
        t=threading.Thread(target=start_loop)
        t.start()
        
    #elif key==keyboard.Key.tab:   #if this is used, the attributes related to 'key' will be changed. you can see them since I have used a print(dir(key))
    elif key.char == 'q':
        loop_running=False
        

def start_loop():
    global loop_running
    loop_running = True
    for i in range(100):
        if not loop_running:
            os._exit(0)                          
            
        print(i)
        time.sleep(1)
        
with keyboard.Listener(on_press=on_press) as listner:
    listner.join()