how to verify whether a compressed .gz is corrupted or not?

Question

I have many gz downloaded from the internet, and I would like to make sure they are not corrupted.

Does the fact that I can open the archive with winzip on windows proves that everything is fine?

I must find a way to check their integrity without unzipping them, as they are way too big. Using Python can be an option.

Thanks!

To know if opening verifies the checksum, we'd need to know what tool you're opening with. — Michael Kohne, Apr 22 '16 at 12:56
also good ansver for similar question https://unix.stackexchange.com/a/359306/18674 — Mikhail Moskalev, Jan 08 '21 at 23:48
Why is size a problem? Does it take too long? Take too much diskspace? Just too many files to do them all by hand? — Ben Aveling, Dec 24 '21 at 06:58

score 13 · Accepted Answer · edited May 23 '17 at 11:33

13

Using the gunzip test option

gzip -t file.tar.gz

See How to check if a Unix .tar.gz file is a valid file without uncompressing

edited May 23 '17 at 11:33

Community

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answered Apr 22 '16 at 13:14

shsh

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thanks! is it possible to do that in python with the gzip module? – ℕʘʘḆḽḘ Apr 22 '16 at 13:16
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You can use `os.system("command")` or `subprocess.call("command")` – shsh Apr 22 '16 at 13:28

score 4 · Answer 2 · answered Apr 22 '16 at 12:23

4

Most sites will give you a check sum of some kind to check the file is good. Most of the time it is a md5sum but there are a few out there. If you can open it that is a good sign but it doesn't always mean it is good.

answered Apr 22 '16 at 12:23

Mat000111

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score 2 · Answer 3 · answered Apr 22 '16 at 12:50

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Calculate the md5 hash of the file using md5sum filename
Compare the 2 provided hashes (the one you generated and the one that is provided by the website as @Mat000111 said. if they are different, then the file has been modified or it is corrupted

answered Apr 22 '16 at 12:50

Jalal Mostafa

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score 2 · Answer 4 · answered Apr 22 '16 at 12:56

2

The gzip utility has a '-t' option which tests file integrity without bothering to unpack the file. That'll tell you if gzip thinks the file is OK.

answered Apr 22 '16 at 12:56

Michael Kohne

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great idea. how would I do that in the command line? sorry I am not very familiar with linux – ℕʘʘḆḽḘ Apr 22 '16 at 12:57
or could I do that in python? – ℕʘʘḆḽḘ Apr 22 '16 at 13:13

how to verify whether a compressed .gz is corrupted or not?

4 Answers4