python – What can lead to IOError: [Errno 9] Bad file descriptor during os.system()?

python – What can lead to IOError: [Errno 9] Bad file descriptor during os.system()?

You get this error message if a Python file was closed from the outside, i.e. not from the file objects close() method:

>>> f = open(.bashrc)
>>> os.close(f.fileno())
>>> del f
close failed in file object destructor:
IOError: [Errno 9] Bad file descriptor

The line del f deletes the last reference to the file object, causing its destructor file.__del__ to be called. The internal state of the file object indicates the file is still open since f.close() was never called, so the destructor tries to close the file. The OS subsequently throws an error because of the attempt to close a file thats not open.

Since the implementation of os.system() does not create any Python file objects, it does not seem likely that the system() call is the origin of the error. Maybe you could show a bit more code?

You can get this error if you use wrong mode when opening the file. For example:

    with open(output, wb) as output_file:
        print output_file.read()

In that code, I want to read the file, but I use mode wb instead of r or r+

python – What can lead to IOError: [Errno 9] Bad file descriptor during os.system()?