How to create a temporary file that can be read by a subprocess?

Since nobody else appears to be interested in leaving this information out in the open...

tempfile does expose a function, mkdtemp(), which can trivialize this problem:

try:    temp_dir = mkdtemp()    temp_file = make_a_file_in_a_dir(temp_dir)    do_your_subprocess_stuff(temp_file)    remove_your_temp_file(temp_file)finally:    os.rmdir(temp_dir)

I leave the implementation of the intermediate functions up to the reader, as one might wish to do things like use mkstemp() to tighten up the security of the temporary file itself, or overwrite the file in-place before removing it. I don't particularly know what security restrictions one might have that are not easily planned for by perusing the source of tempfile.

Anyway, yes, using NamedTemporaryFile on Windows might be inelegant, and my solution here might also be inelegant, but you've already decided that Windows support is more important than elegant code, so you might as well go ahead and do something readable.

According to Richard Oudkerk

(...) the only reason that trying to reopen a NamedTemporaryFile fails on Windows is because when we reopen we need to use O_TEMPORARY.

and he gives an example of how to do this in Python 3.3+

import os, tempfileDATA = b"hello bob"def temp_opener(name, flag, mode=0o777):    return os.open(name, flag | os.O_TEMPORARY, mode)with tempfile.NamedTemporaryFile() as f:    f.write(DATA)    f.flush()    with open(f.name, "rb", opener=temp_opener) as f:        assert f.read() == DATAassert not os.path.exists(f.name)

Because there's no opener parameter in the built-in open() in Python 2.x, we have to combine lower level os.open() and os.fdopen() functions to achieve the same effect:

import subprocessimport tempfileDATA = b"hello bob"with tempfile.NamedTemporaryFile() as f:    f.write(DATA)    f.flush()    subprocess_code = \    """import os       f = os.fdopen(os.open(r'{FILENAME}', os.O_RDWR | os.O_BINARY | os.O_TEMPORARY), 'rb')       assert f.read() == b'{DATA}'    """.replace('\n', ';').format(FILENAME=f.name, DATA=DATA)    subprocess.check_output(['python', '-c', subprocess_code]) == DATA

You can always go low-level, though am not sure if it's clean enough for you:

fd, filename = tempfile.mkstemp()try:    os.write(fd, someStuff)    os.close(fd)    # ...run the subprocess and wait for it to complete...finally:    os.remove(filename)