python how to append to file in zip archive

Question

If I do something like this:

from zipfile import ZipFile 

zip = ZipFile(archive, "a")  

for x in range(5):
    zip.writestr("file1.txt", "blabla")

It will create an archive with 5 files all named "file1.txt". What I want to achieve is having one compressed file to which every loop iteration appends some content. Is it possible without having some kind of auxiliary buffer and how to do this?

Solution 1

It's impossible with zipfile package but writing to compressed files is supported in gzip:

import gzip
content = "Lots of content here"
f = gzip.open('/home/joe/file.txt.gz', 'wb')
f.write(content)
f.close()

Solution 2

Its quite possible to append files to compressed archive using Python.

Tested on linux mint 14,Python 2.7

import zipfile

#Create compressed zip archive and add files
z = zipfile.ZipFile("myzip.zip", "w",zipfile.ZIP_DEFLATED)
z.write("file1.ext")
z.write("file2.ext")
z.printdir()
z.close()

#Append files to compressed archive
z = zipfile.ZipFile("myzip.zip", "a",zipfile.ZIP_DEFLATED)
z.write("file3.ext")
z.printdir()
z.close()

#Extract all files in archive
z = zipfile.ZipFile("myzip.zip", "r",zipfile.ZIP_DEFLATED)
z.extractall("mydir")
z.close()

Comments

[Kien Truong]

But gzip can only contain one file.

[Lev Levitsky]

Yep, but it can be used together with tarfile or zipfile.

[Kien Truong]

When you use it with tar, you can not write directly to a single file like this anymore :)

[Lev Levitsky]

What I mean is that the data can be written in gzip-compressed files that are then packed into a tar archive later in the same script.

[Jatin Kumar]

There is no way one can "append" to a file in zip file using the python zipfile library. Please suggest if there is some other library which I can use to append content to a file.

[Charles Duffy]

I believe the clear reading of the question is that the OP wants to append to file1.ext, adding additional content to that existing file in multiple iterations, as opposed to adding additional files.

[Oleg Kokorin]

the question is about to append data into the same file entity inside the ZIP archive but appending another file entity into the same ZIP archive