KeyboardInteruption but for all keys

Question

I have been looking on the web for about an hour searching for a command like Keyboardinterupt, but then for all keys. I need this for an try and Except loop which I want people to quit using any key. Is there another thing like KeyboardInterupt or do i need to become hackerman?

Thanks for your time

Answer 1

KeyboardInterrupt is an exception raised when Python catches the SIGINT system signal. You can raise it yourself at will: raise KeyboardInterrupt. However, you cannot generate the SIGINT signal yourself, the signal has to be sent to the process. A similar effect is achieved by pressing CTRL-C, which emits the SIGINT signal to the running process.

If you have a loop and want to break it on a key, you have to listen for any keyboard event and raise an exception when it is caught; you need a mechanism to execute your code and listening for events at the same time.

I can imagine something like this:

• you start a Python subprocess with your code
• you enter a loop, catching any keyboard keypress
• when you get the keypress event you send the SIGINT signal to the other process

Example, Python 2.7 (not tested):

import multiprocessing
import time
import signal
import select
import sys
import os

def my_code():
  while True:
    print 'Do something...'
    time.sleep(1)

if __name__ == '__main__':
    p = multiprocessing.Process(target=my_code)
    p.start()

    # wait for a key
    select.select([sys.stdin],[],[])

    os.kill(p.pid, signal.SIGINT)

Due to stdin buffering, on Linux at least, the code above requires [Enter] after key is pressed. However, it can be worked-around easily using some Python module like getc for example.