Constantly Running Python Script With User Input

Question

I want to write a python command line script that will accept user input while simultaneously running another function or script at constant intervals. I have written some pseudo-code below to show what I am aiming for:

def main():
    threading.Timer(1.0, function_to_run_in_background).start()

    while True:
        command = raw_input("Enter a command >>")

        if command.lower() == "quit":
            break

def function_to_run_in_background():
    while True:
        print "HI"
        time.sleep(2.0)

if __name__ == "__main__":
    main()

I have tried to make something along these lines work, but usually what happens is that the function_to_run_in_background only runs once and I would like it to run continuously at a specified interval while the main thread of the program accepts user input. Is this close to what I am thinking of or is there a better way?

Should function_to_run_in_background run only once (with a delay of 2 seconds) or once every 2 seconds? — Aran-Fey
– Aran-Fey, Commented Jan 15, 2018 at 21:43
As per my edit for clarification I would like function_to_run_in_background to run once every 2 seconds. — Skysmithio
– Skysmithio, Commented Jan 15, 2018 at 23:54
Timer only runs once (after 2 seconds in your case), as per the documentation. — user707650
– user707650, Commented Jan 16, 2018 at 0:09
A simple alternative is to create a thread (without a timer) that runs an infinite while loop itself, with a sleep function. That won't run your function exactly every 2 seconds, since the function itself takes time, but it may get close to what you want. (sched.scheduler may help.) — user707650
– user707650, Commented Jan 16, 2018 at 0:10

Skysmithio · Accepted Answer · 2018-01-16 14:08:23Z

2

Below is essentially what I was looking for. It was helped along by @Evert as well as the answer located here How to use threading to get user input realtime while main still running in python:

import threading
import time
import sys

def background():
    while True:
        time.sleep(3)
        print 'disarm me by typing disarm'


def save_state():
    print 'Saving current state...\nQuitting Plutus. Goodbye!'

# now threading1 runs regardless of user input
threading1 = threading.Thread(target=background)
threading1.daemon = True
threading1.start()

while True:
    if raw_input().lower() == 'quit':
        save_state()
        sys.exit()
    else:
        print 'not disarmed'`

answered Jan 16, 2018 at 14:08

Skysmithio

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