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I see here that a tar is used to merge several files into one. So why do I see so often one zip file in a tar?

example : archive.zip.tar

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    That's not common at all in my experience, where did you see that? (.tar.gz and variations on the other hand is extremely common.)
    – Mat
    Nov 17, 2015 at 11:13
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    because people do all sorts of strange things. and it's not illegal (or even immoral) to put a .zip inside a tar file.
    – cas
    Nov 17, 2015 at 11:14
  • Maybe someone put a zip in a tar file to avoid a naive email attachment filter.
    – Joshua Taylor
    Nov 17, 2015 at 14:23
  • why do you tar zip file?
    – mikeserv
    Nov 17, 2015 at 14:43

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Tar doesn't compress* - it's 'tape archive' and exists purely to serialise data - traditionally to a tape device.

It serialises a directory structure, including permissions and file contents.

gzip doesn't preserve structure, and just compresses on a 'file' bases - hence why you tend to get .tar.gz - it's a serialised structure that has then been compressed.

I don't know why you'd get .zip.tar though, given that zip does support directory structures, permissions and compression. It seems largely nonsensical to do so.

* newer versions of tar include the z flag to compress - this wasn't part of the original spec. So you'd tar cvf - ./path_to_tar | gzip -c > file.tar.gz

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  • Doesn't it matter for the inode count? askubuntu.com/questions/436679/…
    – Thomas
    Nov 17, 2015 at 11:31
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    You save the same number of inodes through tar and through zip; you save nothing if you use both at once.
    – SF.
    Nov 17, 2015 at 11:41
  • Actually, just tar cv ./path_to_tar | gzip .., f - is unnecessary.
    – muru
    Nov 17, 2015 at 15:13

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