How to exit from python without traceback?

Question

I would like to know how to I exit from python without having an traceback dump on the output.

I still want want to be able to return an error code but I do not want to display the traceback log.

I want to be able to exit using exit(number) without trace but in case of an Exception (not an exit) I want the trace.

Answer 1

import sys
sys.exit(1)

Answer 2

something like import sys; sys.exit(0) ?

Answer 3

You are presumably encountering an exception and the program is exiting because of this (with a traceback). The first thing to do therefore is to catch that exception, before exiting cleanly (maybe with a message, example given).

Try something like this in your main routine:

import sys

def main():
    try:
        do main program stuff here
        ....
    except KeyboardInterrupt:
        print "Shutdown requested...exiting"
    except Exception, e:
        print "An unexpected exception was encountered: %s" % str(e)
        sys.exit(1)
    sys.exit(0)

if __name__ == "__main__":
    main()

Answer 4

Perhaps you're trying to catch Exception and this is catching the SystemExit exception raised by sys.exit()?

import sys

try:
    sys.exit(1) # Or something that calls sys.exit()
except SystemExit, e:
    sys.exit(e)
except Exception:
    # Cleanup and reraise. This will print a backtrace.
    # (Insert your cleanup code here.)
    raise

In general, catching Exception is a bad idea. You'll catch all kinds of stuff you don't want to catch -- like SystemExit -- and it can also mask your own programming errors. My example above is silly, unless you're doing something in terms of cleanup. You could replace it with:

import sys
sys.exit(1) # Or something that calls sys.exit().

If you need to exit without raising SystemExit:

import os
os._exit(1)

I do this, in code that runs under unittest and calls fork(). Unittest gets when the forked process raises SystemExit. This is definitely a corner case!

Answer 5

Thanks to bspierre for pointing out the SystemExit exception

Here is how I do:

try:
    #some function call doing a sys.exit
    ...
except SystemExit:
    pass

By the way if you want to specify the exception variable in python 3 you have to do

except SystemExit as e:
    sys.exit(e)

it is "as" instead of a comma (http://www.python.org/dev/peps/pep-3110/#grammar-changes)