Exit python properly

Question

I knew that sys.exit() raises an Exit exception, so when I run this I knew it wouldn't exit:

In [25]: try:
   ....:     sys.exit()
   ....: except:
   ....:     print "oops"
   ....:     
oops

But I thought that os._exit() was meant to exit using a C call, but it's also causing an exception:

In [28]: try:
   ....:     os._exit()
   ....: except:
   ....:     print "oops"
   ....:     
oops

Is there a way of doing this without killing the PID?

You should never use except without a specific exception.

msvalkon
– msvalkon

2012-06-05 16:08:58 +00:00
Commented Jun 5, 2012 at 16:08 — msvalkon
– msvalkon, Commented Jun 5, 2012 at 16:08

mgilson · Accepted Answer · 2012-06-05 16:07:08Z

9

I'm not sure I understand your question, but os._exit isn't raising an exception -- you calling os._exit with the wrong number of arguments is:

try:
    os._exit()
except Exception as e:
    print e

#output: _exit() takes exactly 1 argument (0 given)

answered Jun 5, 2012 at 16:07

mgilson

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schlamar · Accepted Answer · 2012-06-05 16:54:23Z

4

Don't use except without an Exception class, so sys.exit will just work fine without triggering the exception handling:

>>> import sys
>>> try:
...     sys.exit()
... except Exception:
...     print 'oops'
... 
$

There are other exceptions which are triggered with a plain except clause (and in general shouldn't), especially KeyboardInterrupt.

edited Jun 5, 2012 at 16:54

answered Jun 5, 2012 at 16:07

schlamar

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5 Comments

Jonathan Eunice Over a year ago

I know this is the conventional wisdom--and even more so, to use a narrowly-specified, specific exception. But when you're going to catch every exception and not going to use the exception data (e.g. contra @mgilson's answer), is there really any virtue in except Exception? Is there any non-Exception possibility that will trigger the except clause?

schlamar Over a year ago

@ire_and_curses This does exit the process without triggering the exception handler.

ire_and_curses Over a year ago

@ms4py - I see. That's interesting! Vote redacted!

schlamar Over a year ago

@JonathanEunice Please re-read my answer, it should be more clear now :)

Val Over a year ago

Why do people lie over and over again? It is very easy to check that sys.exit() throws a SystemExit exception

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