Python's zipfile module cannot update entries [duplicate]

Question

I would like to update an entry in a zip file using pythons zipfile module. My problem is that this generates a new entry.

Please assume I have this code:

from zipfile import ZipFile,ZIP_DEFLATED
with ZipFile("myfile.zip","w") as z:
    z.writestr("hello.txt", "the content of hello.txt", ZIP_DEFLATED)
    ###  how to update the hello.txt file here ?
    z.writestr("hello.txt", "the content of hello.txt", ZIP_DEFLATED)

After this the actual zip file has two entries instead of one:

$ unzip -l myfile.zip 
Archive:  myfile.zip
  Length      Date    Time    Name
---------  ---------- -----   ----
       24  2013-02-19 22:48   hello.txt
       24  2013-02-19 22:48   hello.txt
---------                     -------
       48                     2 files
$ python --version
Python 3.3.0
$

I know of the method to write a complete new file, but this would take much time if the content is big.

The zip(1) utility can do this ( using the "-u" option) so why not python? Is there any way I can still achieve this using python?

Answer 1

I doubt the zipfile module can modify archives like you want. If it could, there would be a method to remove a file from a ZipFile, which there isn't.