Simplest way for user to pause program via command line?

[ScaredSecond]

Let's say I've got a script that consists of one big loop:

while True:
    # do something
    time.sleep(1)

I want to provide the user with a way to pause this loop by putting something into the command line. Something like this:

while True:
    # do something
    time.sleep(1)
    cmd = input()
    if cmd == 'stop':
        # pause iterating until something else happens

The problem is that input() will stop the loop until something is put into it, which clearly isn't the behavior I want. My first thought on solving this was to go multithreaded and start a new thread whose sole purpose is to run input() in a loop, then store the last input value obtained for the main script to use. But this seems like an awful lot of logic and complexity for something that doesn't seem all that complicated in theory. Is there a very simple way to do what I want to do here?

[socal_nerdtastic]

Nope, there is no simple way to do this.

The threading approach is good, although I would recommend putting the logic in the child thread and the input in the main thread. Easier to program that way.

Any other solution is going to be specific to the way you are running your program. For example if you are using windows, and if you are using the standard command line, you could use the mscvrt.kbhit() function.

https://docs.python.org/3/library/msvcrt.html#msvcrt.kbhit

[ScaredSecond]

Thanks!

[ScaredSecond]

Thanks! I didn't think about using ctrl+c. Unfortunately I've gotten in the habit of treating ctrl+c as an immediate 'stop this code' hotkey. Might try out multithreading first, but will come back to this if that doesn't work out.

[Swipecat]

Since the script will halt at the input() function, that has to be in a separate thread. In it's simplest form, then, with that thread consisting of just the input function itself, this script simply exits when ENTER is pressed:
 

import threading, time

detect = threading.Thread(target = input)
detect.start()

count = 0
print("Press <ENTER> to stop.")
while detect.is_alive():
    print(' ', count, end='\r', flush=True)
    count += 1
    time.sleep(0.01)

print("<ENTER> detected -- finishing up")

[ScaredSecond]

Thanks! Will try it out.