Python - Infinite while loop, break on user input

On python 3.5 you can use the following code. It can be adjusted for a specific keystroke. The while loop will keep running until the user presses a key.

import time
import threading

# set global variable flag
flag = 1

def normal():
    global flag
    while flag==1:
        print('normal stuff')
        time.sleep(2)
        if flag==False:
            print('The while loop is now closing')


def get_input():
    global flag
    keystrk=input('Press a key \n')
    # thread doesn't continue until key is pressed
    print('You pressed: ', keystrk)
    flag=False
    print('flag is now:', flag)

n=threading.Thread(target=normal)
i=threading.Thread(target=get_input)
n.start()
i.start()

I think you can do better with msvcrt:

import msvcrt, time
i = 0
while True:
    i = i + 1
    if msvcrt.kbhit():
        if msvcrt.getwche() == '\r':
            break
    time.sleep(0.1)
print(i)

Sadly, still windows-specific.

You can use non-blocking read from stdin:

import sys
import os
import fcntl
import time

fl = fcntl.fcntl(sys.stdin.fileno(), fcntl.F_GETFL)
fcntl.fcntl(sys.stdin.fileno(), fcntl.F_SETFL, fl | os.O_NONBLOCK)
while True:
    print("Waiting for user input")
    try:
        stdin = sys.stdin.read()
        if "\n" in stdin or "\r" in stdin:
            break
    except IOError:
        pass
    time.sleep(1)