How would you prompt the user for some input but timing out after N seconds?
Google is pointing to a mail thread about it at http://mail.python.org/pipermail/python-list/2006-January/533215.html but it seems not to work. The statement in which the timeout happens, no matter whether it is a sys.input.readline or timer.sleep(), I always get:
<type 'exceptions.TypeError'>: [raw_]input expected at most 1 arguments, got 2
which somehow the except fails to catch.
The example you have linked to is wrong and the exception is actually occuring when calling alarm handler instead of when read blocks. Better try this:
import signal
TIMEOUT = 5 # number of seconds your want for timeout
def interrupted(signum, frame):
"called when read times out"
print 'interrupted!'
signal.signal(signal.SIGALRM, interrupted)
def input():
try:
print 'You have 5 seconds to type in your stuff...'
foo = raw_input()
return foo
except:
# timeout
return
# set alarm
signal.alarm(TIMEOUT)
s = input()
# disable the alarm after success
signal.alarm(0)
print 'You typed', s
Using a select call is shorter, and should be much more portable
import sys, select
print "You have ten seconds to answer!"
i, o, e = select.select( [sys.stdin], [], [], 10 )
if (i):
print "You said", sys.stdin.readline().strip()
else:
print "You said nothing!"
Not a Python solution, but...
I ran in to this problem with a script running under CentOS (Linux), and what worked for my situation was just running the Bash "read -t" command in a subprocess. Brutal disgusting hack, I know, but I feel guilty enough about how well it worked that I wanted to share it with everyone here.
import subprocess
subprocess.call('read -t 30', shell=True)
All I needed was something that waited for 30 seconds unless the ENTER key was pressed. This worked great.
And here's one that works on Windows
I haven't been able to get any of these examples to work on Windows so I've merged some different StackOverflow answers to get the following:
import threading, msvcrt
import sys
def readInput(caption, default, timeout = 5):
class KeyboardThread(threading.Thread):
def run(self):
self.timedout = False
self.input = ''
while True:
if msvcrt.kbhit():
chr = msvcrt.getche()
if ord(chr) == 13:
break
elif ord(chr) >= 32:
self.input += chr
if len(self.input) == 0 and self.timedout:
break
sys.stdout.write('%s(%s):'%(caption, default));
result = default
it = KeyboardThread()
it.start()
it.join(timeout)
it.timedout = True
if len(it.input) > 0:
# wait for rest of input
it.join()
result = it.input
print '' # needed to move to next line
return result
# and some examples of usage
ans = readInput('Please type a name', 'john')
print 'The name is %s' % ans
ans = readInput('Please enter a number', 10 )
print 'The number is %s' % ans
Paul's answer did not quite work. Modified code below which works for me on
windows 7 x64
vanilla CMD shell (eg, not git-bash or other non-M$ shell)
-- nothing msvcrt works in git-bash it appears.
python 3.6
(I'm posting a new answer, because editing Paul's answer directly would change it from python 2.x-->3.x, which seems too much for an edit (py2 is still in use)
import sys, time, msvcrt
def readInput( caption, default, timeout = 5):
start_time = time.time()
sys.stdout.write('%s(%s):'%(caption, default))
sys.stdout.flush()
input = ''
while True:
if msvcrt.kbhit():
byte_arr = msvcrt.getche()
if ord(byte_arr) == 13: # enter_key
break
elif ord(byte_arr) >= 32: #space_char
input += "".join(map(chr,byte_arr))
if len(input) == 0 and (time.time() - start_time) > timeout:
print("timing out, using default value.")
break
print('') # needed to move to next line
if len(input) > 0:
return input
else:
return default
# and some examples of usage
ans = readInput('Please type a name', 'john')
print( 'The name is %s' % ans)
ans = readInput('Please enter a number', 10 )
print( 'The number is %s' % ans)
I spent a good twenty minutes or so on this, so I thought it was worth a shot to put this up here. It is directly building off of user137673's answer, though. I found it most useful to do something like this:
#! /usr/bin/env python
import signal
timeout = None
def main():
inp = stdinWait("You have 5 seconds to type text and press <Enter>... ", "[no text]", 5, "Aw man! You ran out of time!!")
if not timeout:
print "You entered", inp
else:
print "You didn't enter anything because I'm on a tight schedule!"
def stdinWait(text, default, time, timeoutDisplay = None, **kwargs):
signal.signal(signal.SIGALRM, interrupt)
signal.alarm(time) # sets timeout
global timeout
try:
inp = raw_input(text)
signal.alarm(0)
timeout = False
except (KeyboardInterrupt):
printInterrupt = kwargs.get("printInterrupt", True)
if printInterrupt:
print "Keyboard interrupt"
timeout = True # Do this so you don't mistakenly get input when there is none
inp = default
except:
timeout = True
if not timeoutDisplay is None:
print timeoutDisplay
signal.alarm(0)
inp = default
return inp
def interrupt(signum, frame):
raise Exception("")
if __name__ == "__main__":
main()
Following code worked for me.
I used two threads one to get the raw_Input and another to wait for a specific time. If any of the thread exits, both the thread is terminated and returned.
def _input(msg, q):
ra = raw_input(msg)
if ra:
q.put(ra)
else:
q.put("None")
return
def _slp(tm, q):
time.sleep(tm)
q.put("Timeout")
return
def wait_for_input(msg="Press Enter to continue", time=10):
q = Queue.Queue()
th = threading.Thread(target=_input, args=(msg, q,))
tt = threading.Thread(target=_slp, args=(time, q,))
th.start()
tt.start()
ret = None
while True:
ret = q.get()
if ret:
th._Thread__stop()
tt._Thread__stop()
return ret
return ret
print time.ctime()
t= wait_for_input()
print "\nResponse :",t
print time.ctime()
Analogous to Locane's for windows:
import subprocess
subprocess.call('timeout /T 30')
Here is a portable and simple Python 3 solution using threads. This is the only one that worked for me while being cross-platform.
Other things I tried all had problems:
from threading import Thread
class myClass:
_input = None
def __init__(self):
get_input_thread = Thread(target=self.get_input)
get_input_thread.daemon = True # Otherwise the thread won't be terminated when the main program terminates.
get_input_thread.start()
get_input_thread.join(timeout=20)
if myClass._input is None:
print("No input was given within 20 seconds")
else:
print("Input given was: {}".format(myClass._input))
@classmethod
def get_input(cls):
cls._input = input("")
return
my cross platform solution
def input_process(stdin_fd, sq, str):
sys.stdin = os.fdopen(stdin_fd)
try:
inp = input (str)
sq.put (True)
except:
sq.put (False)
def input_in_time (str, max_time_sec):
sq = multiprocessing.Queue()
p = multiprocessing.Process(target=input_process, args=( sys.stdin.fileno(), sq, str))
p.start()
t = time.time()
inp = False
while True:
if not sq.empty():
inp = sq.get()
break
if time.time() - t > max_time_sec:
break
p.terminate()
sys.stdin = os.fdopen( sys.stdin.fileno() )
return inp
add if name=='main': #required by multiprocessing on windows
import sys, os, multiprocessing, time
def input_process(stdin_fd, sq, sstr):
sys.stdin = os.fdopen(stdin_fd)
try:
inp = input(sstr)
sq.put(True)
except:
sq.put(False)
def input_in_time(sstr, max_time_sec):
sq = multiprocessing.Queue()
p = multiprocessing.Process(target=input_process, args=( sys.stdin.fileno(), sq, sstr))
p.start()
t = time.time()
inp = False
while True:
if not sq.empty():
inp = sq.get()
break
if time.time() - t > max_time_sec:
break
tleft=int( (t+max_time_sec)-time.time())
if tleft<max_time_sec-1 and tleft>0:
print('\n ...time left '+str(tleft)+'s\ncommand:')
time.sleep(2)
p.terminate()
sys.stdin = os.fdopen( sys.stdin.fileno() )
return inp
if __name__=='__main__':
input_in_time("command:", 17)
This is the way I approached this problem. I haven't tested it thoroughly, and I'm not sure it doesn't have some important problems, but considering other solutions are far from perfect as well, I decided to share:
import sys
import subprocess
def switch():
if len(sys.argv) == 1:
main()
elif sys.argv[1] == "inp":
print(input(''))
else:
print("Wrong arguments:", sys.argv[1:])
def main():
passw = input_timed('You have 10 seconds to enter password:', timeout=10)
if passw is None:
print("Time's out! You explode!")
elif passw == "PasswordShmashword":
print("H-h-how did you know you h-h-hacker")
else:
print("I spare your life because you at least tried")
def input_timed(*args, timeout, **kwargs):
"""
Print a message and await user input - return None if timedout
:param args: positional arguments passed to print()
:param timeout: number of seconds to wait before returning None
:param kwargs: keyword arguments passed to print()
:return: user input or None if timed out
"""
print(*args, **kwargs)
try:
out: bytes = subprocess.run(["python", sys.argv[0], "inp"], capture_output=True, timeout=timeout).stdout
except subprocess.TimeoutExpired:
return None
return out.decode('utf8').splitlines()[0]
switch()
For Linux, I would prefer the select version by @Pontus. Here just a python3 function works like read in shell:
import sys, select
def timeout_input(prompt, timeout=3, default=""):
print(prompt, end=': ', flush=True)
inputs, outputs, errors = select.select([sys.stdin], [], [], timeout)
print()
return (0, sys.stdin.readline().strip()) if inputs else (-1, default)
Run
In [29]: timeout_input("Continue? (Y/n)", 3, "y")
Continue? (Y/n):
Out[29]: (-1, 'y')
In [30]: timeout_input("Continue? (Y/n)", 3, "y")
Continue? (Y/n): n
Out[30]: (0, 'n')
And a yes_or_no function
In [33]: yes_or_no_3 = lambda prompt: 'n' not in timeout_input(prompt + "? (Y/n)", 3, default="y")[1].lower()
In [34]: yes_or_no_3("Continue")
Continue? (Y/n):
Out[34]: True
In [35]: yes_or_no_3("Continue")
Continue? (Y/n): no
Out[35]: False
A late answer :)
I would do something like this:
from time import sleep
print('Please provide input in 20 seconds! (Hit Ctrl-C to start)')
try:
for i in range(0,20):
sleep(1) # could use a backward counter to be preeety :)
print('No input is given.')
except KeyboardInterrupt:
raw_input('Input x:')
print('You, you! You know something.')
I know this is not the same but many real life problem could be solved this way. (I usually need timeout for user input when I want something to continue running if the user not there at the moment.)
Hope this at least partially helps. (If anyone reads it anyway :) )
