Does python's `os.system` ever throw an exception?

Might the esteemed os.system of Python fame开发者_StackOverflow throw an exception? If so, which ones?

---

Short answer: yes:

>>> import os
>>> os.system(None)
TypeError ...

Long answer: look here http://docs.python.org/library/subprocess.html#subprocess-replacements to see how to avoid using os.system.

---

On POSIX systems it appears to be a straight pass-through to system() (listing from Python 2.7.1's posixmodule.c):

static PyObject *
posix_system(PyObject *self, PyObject *args)
{
    char *command;
    long sts;
    if (!PyArg_ParseTuple(args, "s:system", &command))
        return NULL;
    Py_BEGIN_ALLOW_THREADS
    sts = system(command);
    Py_END_ALLOW_THREADS
    return PyInt_FromLong(sts);
}

---

os.system throws a TypeError if there is not exactly one string argument. If the fork fails due to resource or ulimit restrictions, it will return -1. If the argument is not valid in some way (like non-existing command), it will return a high error code. Apart from the aforementioned TypeError, os.system does not throw any exceptions.

---

If you're asking whether it throws an exception when the process you're calling ends with an error, the answer is no, you can call a program with os.system(), have it error out, and you will never know.

That's why you should use the subprocess module.