Size of an open file object

Question

Is there a way to find the size of a file object that is currently open?

Specifically, I am working with the tarfile module to create tarfiles, but I don't want my tarfile to exceed a certain size. As far as I know, tarfile objects are file-like objects, so I imagine a generic solution would work.

Answer 1

$ ls -la chardet-1.0.1.tgz -rwxr-xr-x 1 vinko vinko 179218 2008-10-20 17:49 chardet-1.0.1.tgz $ python Python 2.5.1 (r251:54863, Jul 31 2008, 22:53:39) [GCC 4.1.2 (Ubuntu 4.1.2-0ubuntu4)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> f = open('chardet-1.0.1.tgz','rb') >>> f.seek(0,2) >>> f.tell() 179218L 

Adding ChrisJY's idea to the example

>>> import os >>> os.fstat(f.fileno()).st_size 179218L >>>         

Note: Based on the comments, f.seek(0, 2) is must before calling f.tell(), without which it would return a size of 0. The reason is that f.seek(0, 2) moves the file object's position to the end of the file.

Answer 2

Well, if the file object support the tell method, you can do:

current_size = f.tell() 

That will tell you were it is currently writing. If you write in a sequential way this will be the size of the file.

Otherwise, you can use the file system capabilities, i.e. os.fstat as suggested by others.