["python","exit"]
Difference between exit() and sys.exit() in Python

In Python, there are two similarly-named functions, exit() and sys.exit(). What's the difference and when should I use one over the other?
exit is a helper for the interactive shell - sys.exit is intended for use in programs. The site module (which is imported automatically during startup, except if the -S command-line option is given) adds several constants to the built-in namespace (e.g. exit). They are useful for the interactive interpreter shell and should not be used in programs. Technically, they do mostly the same: raising SystemExit. sys.exit does so in sysmodule.c: static PyObject * sys_exit(PyObject *self, PyObject *args) { PyObject *exit_code = 0; if (!PyArg_UnpackTuple(args, "exit", 0, 1, &exit_code)) return NULL; /* Raise SystemExit so callers may catch it or clean up. */ PyErr_SetObject(PyExc_SystemExit, exit_code); return NULL; } While exit is defined in site.py and _sitebuiltins.py, respectively. class Quitter(object): def __init__(self, name): self.name = name def __repr__(self): return 'Use %s() or %s to exit' % (self.name, eof) def __call__(self, code=None): # Shells like IDLE catch the SystemExit, but listen when their # stdin wrapper is closed. try: sys.stdin.close() except: pass raise SystemExit(code) __builtin__.quit = Quitter('quit') __builtin__.exit = Quitter('exit') Note that there is a third exit option, namely os._exit, which exits without calling cleanup handlers, flushing stdio buffers, etc. (and which should normally only be used in the child process after a fork()).