Capture keyboardinterrupt in Python without try-except

Question

Is there some way in Python to capture KeyboardInterrupt event without putting all the code inside a try-except statement   I want to cleanly exit without trace if user presses Ctrl C

User · Answer

An alternative to setting your own signal handler is to use a context-manager to catch the exception and ignore it:

>>> class CleanExit(object):
...     def __enter__(self):
...             return self
...     def __exit__(self, exc_type, exc_value, exc_tb):
...             if exc_type is KeyboardInterrupt:
...                     return True
...             return exc_type is None
... 
>>> with CleanExit():
...     input()    #just to test it
... 
>>>

This removes the try-except block while preserving some explicit mention of what is going on.

This also allows you to ignore the interrupt only in some portions of your code without having to set and reset again the signal handlers everytime.

User · Answer

If someone is in search for a quick minimal solution  import signal    The code which crashes program on interruption  signal signal signal SIGINT  call this function if interrupted     The code skipped if interrupted

User · Answer

I know this is an old question but I came here first and then discovered the atexit module  I do not know about its cross-platform track record or a full list of caveats yet  but so far it is exactly what I was looking for in trying to handle post-KeyboardInterrupt cleanup on Linux  Just wanted to throw in another way of approaching the problem   I want to do post-exit clean-up in the context of Fabric operations  so wrapping everything in try except wasn t an option for me either  I feel like atexit may be a good fit in such a situation  where your code is not at the top level of control flow   atexit is very capable and readable out of the box  for example   import atexit  def goodbye        print  You are now leaving the Python sector    atexit register goodbye    You can also use it as a decorator  as of 2 6  this example is from the docs    import atexit   atexit register def goodbye        print  You are now leaving the Python sector     If you wanted to make it specific to KeyboardInterrupt only  another person s answer to this question is probably better   But note that the atexit module is only  70 lines of code and it would not be hard to create a similar version that treats exceptions differently  for example passing the exceptions as arguments to the callback functions   The limitation of atexit that would warrant a modified version  currently I can t conceive of a way for the exit-callback-functions to know about the exceptions  the atexit handler catches the exception  calls your callback s   then re-raises that exception  But you could do this differently    For more info see    Official documentation on atexit The Python Module of the Week post  a good intro

User · Answer

If all you want is to not show the traceback  make your code like this      all your app logic here def main          whatever your app does    if   name         main        try        main      except KeyboardInterrupt          do nothing here       pass    Yes  I know that this doesn t directly answer the question  but it s not really clear why needing a try except block is objectionable -- maybe this makes it less annoying to the OP

User · Answer

You can prevent printing a stack trace for KeyboardInterrupt  without try      except KeyboardInterrupt  pass  the most obvious and propably  best  solution  but you already know it and asked for something else  by replacing sys excepthook  Something like  def custom excepthook type  value  traceback       if type is KeyboardInterrupt          return   do nothing     else          sys   excepthook   type  value  traceback

User · Answer

I tried the suggested solutions by everyone  but I had to improvise code myself to actually make it work  Following is my improvised code   import signal import sys import time  def signal handler signal  frame       print  You pressed Ctrl C        print signal    Value is 2 for CTRL   C     print frame    Where your execution of program is at moment - the Line Number     sys exit 0    Assign Handler Function signal signal signal SIGINT  signal handler     Simple Time Loop of 5 Seconds secondsCount   5 print  Press Ctrl C in next   str secondsCount   timeLoopRun   True  while timeLoopRun        time sleep 1      if secondsCount  lt  1          timeLoopRun   False     print  Closing in    str secondsCount     seconds       secondsCount   secondsCount - 1

User · Answer

Yes  you can install an interrupt handler using the module signal  and wait forever using a threading Event   import signal import sys import time import threading  def signal handler signal  frame       print  You pressed Ctrl C        sys exit 0   signal signal signal SIGINT  signal handler  print  Press Ctrl C   forever   threading Event   forever wait

[python] Capture keyboardinterrupt in Python without try-except

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