Python – How to Catch sys.exit()

I wanted to catch a sys.exit() call in my code (using Python 2.5) and handle it but alas even this wasn’t working:

import sys
try:
    sys.exit()
except Exception,Err:
    print 'hi'

It would just exit the script.

I found this is the way to go when you truly want to capture all exceptions:

try:
    sys.exit()
except BaseException,Err:
    print 'hi'

Please correct me if I’m missing anything. Are there any exceptions I still won’t catch?

Posted by Greg Pinero (Primary Searcher) on Oct 31st, 2007 and is filed under Python.

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5 Responses to “Python – How to Catch sys.exit()”

  1. Anonymous says:
    October 31st, 2007 at 10:49 pm

    Is there some reason you’re not just doing:


    try:
    sys.exit()
    except:
    print 'hi'
    ?

    This annoys pylint, but AFAIK it's the only guaranteed way to catch all exceptions. (Runtime exceptions are supposed to extend the Exception base class, but not all code does it. pyserial, I'm looking at you.)

  2. sri says:
    October 31st, 2007 at 11:19 pm

    I’m assuming that you’re using Python 2.5.
    Check out this page:
    http://docs.python.org/whatsnew/pep-352.html

    KeyboardInterrupt is the other exception
    that won’t be caught by your
    ‘except Exception:’ clause.

  3. Chris says:
    November 1st, 2007 at 3:27 am

    As sri said, if you really want to catch all exceptions in Python 2.5, use BaseException instead of Exception.

  4. Greg Pinero (Primary Searcher) says:
    November 1st, 2007 at 11:46 am

    Thanks, so I guess I want BaseException. Good to know.

  5. Jim says:
    November 5th, 2007 at 7:23 pm

    Nope, if you really want to catch all exceptions, you also have to remember that you can raise *strings* as exceptions too.