How to replace the "KeyboardInterrupt" command for another key?

Question

I have the following code:

while True:
    try:
        #DoSomething
    except KeyboardInterrupt:
        break

But instead of using Crtl + C, I want to type another key to end the loop. How can I do this?

Inside the loop you'll need to check if a key has been pressed, and if so, get it and see if it's the one that stops the loop. Checking for keypresses is OS-depend, although there are some third-party modules that work on several platforms that can do that (and more). — martineau
– martineau, Commented Jul 21, 2021 at 19:31
Here's one of them named keyboard and another named pynput. — martineau
– martineau, Commented Jul 21, 2021 at 19:37
Ctrl+C is standard method to stop script in system and it is processed by system - for other keys you have to use some module to check pressed keys and raise KeyboardInterrupt or use while running and set running = False — furas
– furas, Commented Jul 21, 2021 at 20:15

Alan Bagel · Accepted Answer · 2021-07-21 21:03:11Z

2

You can use the keyboard module:

import keyboard

while True:
    if keyboard.is_pressed("some key"):
        break

    do_something()

This will keep doing something until some key is pressed. Then, it will break out of the endless loop.

To catch hotkeys, use the add_hotkey function:

import keyboard


def handle_keypress(key):
    global running

    running = False
    print(key + " was pressed!")


running = True
keyboard.add_hotkey("ctrl+e", lambda: handle_keypress("Ctrl-E"))

while running:
    do_something()

Or you can use pynput:

from pynput.keyboard import Listener


def on_press(key):
    print('{0} pressed'.format(
        key))


with Listener(
        on_press=on_press) as listener:

    listener.join()

edited Jul 21, 2021 at 21:03

answered Jul 21, 2021 at 20:55

Alan Bagel

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1 Comment

ruxtain Over a year ago

About "keyboard", these's an Erorr when you're not root: ImportError: You must be root to use this library on linux.

martineau · Accepted Answer · 2021-07-21 20:17:04Z

1

Here's a simple example of using that keyboard module I mentioned in my second comment. It handles most of steps I mentioned in my first comment and works on several platforms. The loop will stop if and when the user presses the Ctrl + B key.

Note that Ctrl + C will still raise a KeyboardInterrupt.

import keyboard
from time import sleep

def callback(keyname):
    global stopped
    print(f'{keyname} was pressed!')
    stopped = True

keyboard.add_hotkey('ctrl+b', lambda: callback('Ctrl-B'))

stopped = False
print('Doing something...')
while not stopped:
    sleep(1)  # Something

print('-fini-')

answered Jul 21, 2021 at 20:17

martineau

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