Extract only a single directory from tar (in python)

Question

I am working on a project in python in which I need to extract only a subfolder of tar archive not all the files. I tried to use

tar = tarfile.open(tarfile)
tar.extract("dirname", targetdir)

But this does not work, it does not extract the given subdirectory also no exception is thrown. I am a beginner in python. Also if the above function doesn't work for directories whats the difference between this command and tar.extractfile() ?

extractfile() doesn't write a file to the disk, it just gives you a python object. extract() writes to the disk. — ed.
– ed., Commented Nov 4, 2011 at 12:14

taleinat · Accepted Answer · 2016-01-11 15:03:18Z

23

Building on the second example from the tarfile module documentation, you could extract the contained sub-folder and all of its contents with something like this:

with tarfile.open("sample.tar") as tar:
    subdir_and_files = [
        tarinfo for tarinfo in tar.getmembers()
        if tarinfo.name.startswith("subfolder/")
    ]
    tar.extractall(members=subdir_and_files)

This creates a list of the subfolder and its contents, and then uses the recommended extractall() method to extract just them. Of course, replace "subfolder/" with the actual path (relative to the root of the tar file) of the sub-folder you want to extract.

edited Jan 11, 2016 at 15:03

answered Nov 4, 2011 at 12:22

taleinat

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Sam Bull · Accepted Answer · 2017-03-29 13:03:50Z

20

The other answer will retain the subfolder path, meaning that subfolder/a/b will be extracted to ./subfolder/a/b. To extract a subfolder to the root, so subfolder/a/b would be extracted to ./a/b, you can rewrite the paths with something like this:

def members(tf):
    l = len("subfolder/")
    for member in tf.getmembers():
        if member.path.startswith("subfolder/"):
            member.path = member.path[l:]
            yield member

with tarfile.open("sample.tar") as tar:
    tar.extractall(members=members(tar))

answered Mar 29, 2017 at 13:03

Sam Bull

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5 Comments

Blake Over a year ago

Works great. You can also rename the top-level folder with this style by doing member.path = os.path.join('new_dirname', member.path[l:])

user8491363 Over a year ago

Great tip. Having tarfile extracted with every useless subdirectory really bugged me.

Ramesh Over a year ago

This works great. Unfortunately, I skipped this answer before by only looking at the best answer.

Folaht Over a year ago

I will delete it. Sorry. I was hoping for an answer to a very similar issue. By the way, this solution is not working for me. I'm getting an error: [Pyright reportGeneralTypeIssues] [E] Argument of type "Generator[TarInfo, None, None]" cannot be assigned to parameter "members" of type "List[TarInfo] | None" in function "extractall" Type "Generator[TarInfo, None, None]" cannot be assigned to type "List[TarInfo] | None" "Generator[TarInfo, None, None]" is incompatible with "List[TarInfo]" Cannot assign to "None"

Sam Bull Over a year ago

Easier to open a new question than leaving a comment with not enough information. The code works correctly if you run it in Python. The error you're showing is a static typing error, not something that will stop the code from functioning. Fix for that error: github.com/python/typeshed/pull/5273

Criminal_Affair_At_SO · Accepted Answer · 2024-05-10 16:54:36Z

2

The problem with all of the other solutions is that they require to access the end of the file before extracting - which means that they cannot be applied to a stream which does not support seeking.

Staring with Python 3.11.4 (I haven't found a way with earlier versions):

strip1 = lambda member, path: member.replace(name=pathlib.Path(*pathlib.Path(member.path).parts[1:]))
with tarfile.open('file.tar.gz', mode='r:gz') as input:
    input.extractall(path=dest, filter=strip1)

extractall accepts a filter that gets called for each file with TarInfo - you unpack the filename, take all parts except the first one and then repack it.

edited May 10, 2024 at 16:54

answered May 10, 2024 at 16:46

Criminal_Affair_At_SO

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