How to find exit code or reason when atexit callback is called in Python?

Question

I want to know if a Python script is terminating correctly or not. For this I am using atexit but the problem is that I do not know how to differentiate if atexit was called with sys.exit(0) or non zero or an exception.

Reasoning: if program ends properly, it will do nothing but if the program ends by an exception or returning an error code (exit status) different than zero I want to trigger some action.

In case you will wonder why I'm not using try/finally is because I want to add the same behaviour for a dozen of scripts that are importing a common module. Instead of modifying all of them, I want to add the atexit() hack to the module being imported and get this behaviour for free in all of them.

Answer 1

You can solve this using sys.excepthook and by monkey-patching sys.exit():

import atexit import sys  class ExitHooks(object):     def __init__(self):         self.exit_code = None         self.exception = None      def hook(self):         self._orig_exit = sys.exit         sys.exit = self.exit         sys.excepthook = self.exc_handler      def exit(self, code=0):         self.exit_code = code         self._orig_exit(code)      def exc_handler(self, exc_type, exc, *args):         self.exception = exc  hooks = ExitHooks() hooks.hook()  def foo():     if hooks.exit_code is not None:         print("death by sys.exit(%d)" % hooks.exit_code)     elif hooks.exception is not None:         print("death by exception: %s" % hooks.exception)     else:         print("natural death") atexit.register(foo)  # test sys.exit(1)