Python nonblocking console input

For Windows, console only, use the msvcrt module:

import msvcrt

num = 0
done = False
while not done:
    print(num)
    num += 1

    if msvcrt.kbhit():
        print "you pressed",msvcrt.getch(),"so now i will quit"
        done = True

For Linux, this article describes the following solution, it requires the termios module:

import sys
import select
import tty
import termios

def isData():
    return select.select([sys.stdin], [], [], 0) == ([sys.stdin], [], [])

old_settings = termios.tcgetattr(sys.stdin)
try:
    tty.setcbreak(sys.stdin.fileno())

    i = 0
    while 1:
        print(i)
        i += 1

        if isData():
            c = sys.stdin.read(1)
            if c == '\x1b':         # x1b is ESC
                break

finally:
    termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_settings)

For cross platform, or in case you want a GUI as well, you can use Pygame:

import pygame
from pygame.locals import *

def display(str):
    text = font.render(str, True, (255, 255, 255), (159, 182, 205))
    textRect = text.get_rect()
    textRect.centerx = screen.get_rect().centerx
    textRect.centery = screen.get_rect().centery

    screen.blit(text, textRect)
    pygame.display.update()

pygame.init()
screen = pygame.display.set_mode( (640,480) )
pygame.display.set_caption('Python numbers')
screen.fill((159, 182, 205))

font = pygame.font.Font(None, 17)

num = 0
done = False
while not done:
    display( str(num) )
    num += 1

    pygame.event.pump()
    keys = pygame.key.get_pressed()
    if keys[K_ESCAPE]:
        done = True

This is the most awesome solution¹ I've ever seen. Pasted here in case link goes down:

#!/usr/bin/env python
'''
A Python class implementing KBHIT, the standard keyboard-interrupt poller.
Works transparently on Windows and Posix (Linux, Mac OS X).  Doesn't work
with IDLE.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as 
published by the Free Software Foundation, either version 3 of the 
License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

'''

import os

# Windows
if os.name == 'nt':
    import msvcrt

# Posix (Linux, OS X)
else:
    import sys
    import termios
    import atexit
    from select import select


class KBHit:

    def __init__(self):
        '''Creates a KBHit object that you can call to do various keyboard things.
        '''

        if os.name == 'nt':
            pass

        else:

            # Save the terminal settings
            self.fd = sys.stdin.fileno()
            self.new_term = termios.tcgetattr(self.fd)
            self.old_term = termios.tcgetattr(self.fd)

            # New terminal setting unbuffered
            self.new_term[3] = (self.new_term[3] & ~termios.ICANON & ~termios.ECHO)
            termios.tcsetattr(self.fd, termios.TCSAFLUSH, self.new_term)

            # Support normal-terminal reset at exit
            atexit.register(self.set_normal_term)


    def set_normal_term(self):
        ''' Resets to normal terminal.  On Windows this is a no-op.
        '''

        if os.name == 'nt':
            pass

        else:
            termios.tcsetattr(self.fd, termios.TCSAFLUSH, self.old_term)


    def getch(self):
        ''' Returns a keyboard character after kbhit() has been called.
            Should not be called in the same program as getarrow().
        '''

        s = ''

        if os.name == 'nt':
            return msvcrt.getch().decode('utf-8')

        else:
            return sys.stdin.read(1)


    def getarrow(self):
        ''' Returns an arrow-key code after kbhit() has been called. Codes are
        0 : up
        1 : right
        2 : down
        3 : left
        Should not be called in the same program as getch().
        '''

        if os.name == 'nt':
            msvcrt.getch() # skip 0xE0
            c = msvcrt.getch()
            vals = [72, 77, 80, 75]

        else:
            c = sys.stdin.read(3)[2]
            vals = [65, 67, 66, 68]

        return vals.index(ord(c.decode('utf-8')))


    def kbhit(self):
        ''' Returns True if keyboard character was hit, False otherwise.
        '''
        if os.name == 'nt':
            return msvcrt.kbhit()

        else:
            dr,dw,de = select([sys.stdin], [], [], 0)
            return dr != []


# Test    
if __name__ == "__main__":

    kb = KBHit()

    print('Hit any key, or ESC to exit')

    while True:

        if kb.kbhit():
            c = kb.getch()
            if ord(c) == 27: # ESC
                break
            print(c)

    kb.set_normal_term()

_{¹ Made by Simon D. Levy, part of a compilation of software he has written and released under the Gnu Lesser General Public License.}

Here a solution that runs under linux and windows using a seperate thread:

import sys
import threading
import time
import Queue

def add_input(input_queue):
    while True:
        input_queue.put(sys.stdin.read(1))

def foobar():
    input_queue = Queue.Queue()

    input_thread = threading.Thread(target=add_input, args=(input_queue,))
    input_thread.daemon = True
    input_thread.start()

    last_update = time.time()
    while True:

        if time.time()-last_update>0.5:
            sys.stdout.write(".")
            last_update = time.time()

        if not input_queue.empty():
            print "\ninput:", input_queue.get()

foobar()