How do I persist to disk a temporary file using Python?

Question

I am attempting to use the 'tempfile' module for manipulating and creating text files. Once the file is ready I want to save it to disk. I thought it would be as simple as using 'shutil.copy'. However, I get a 'permission denied' IOError:

>>> import tempfile, shutil
>>> f = tempfile.TemporaryFile(mode ='w+t')
>>> f.write('foo')
>>> shutil.copy(f.name, 'bar.txt')

Traceback (most recent call last):
  File "<pyshell#5>", line 1, in <module>
    shutil.copy(f.name, 'bar.txt')
  File "C:\Python25\lib\shutil.py", line 80, in copy
    copyfile(src, dst)
  File "C:\Python25\lib\shutil.py", line 46, in copyfile
    fsrc = open(src, 'rb')
IOError: [Errno 13] Permission denied: 'c:\\docume~1\\me\\locals~1\\temp\\tmpvqq3go'
>>>

Is this not intended when using the 'tempfile' library? Is there a better way to do this? (Maybe I am overlooking something very trivial)

Answer 1

I believe this is what you are looking for: http://www.doughellmann.com/PyMOTW/tempfile/tempfile.html

Answer 2

You could always use shutil.copyfileobj, in your example:

shutil.copyfileobj(f, 'bar.txt')

Answer 3

The file you create with TemporaryFile or NamedTemporaryFile is automatically removed when it's closed, which is why you get an error. If you don't want this, you can use mkstemp instead (see the docs for tempfile).

>>> import tempfile, shutil, os
>>> fd, path = tempfile.mkstemp()
>>> os.write(fd, 'foo')
>>> os.close(fd)
>>> shutil.copy(path, 'bar.txt')
>>> os.remove(path)

Answer 4

Starting from python 2.6 you can also use NamedTemporaryFile with the delete= option set to False. This way the temporary file will be accessible, even after you close it.

Note that on Windows (NT and later) you cannot access the file a second time while it is still open. You have to close it before you can copy it. This is not true on Unix systems.