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I have downloaded a multipart ZIP archive. It contains a video file.

Unfortunately, IZarc reports a CRC check fail when extracting the archive. Downloading the archive again is a long task, since I used a freemium digital locker and JDownloader, it will take me several hours to download all files again and I'm even unsure if the result will be better.

So I want to ask: provided that the archive is composed by .zip, .z01 ... .z09 parts, and provided that a few bytes damaged in a video stream don't necessarily make the video unreadable (it's an MP4),

How do I extract a multipart ZIP archive disabling CRC checks or at least preventing the zip utility from deleting a file that fails the check?

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1 Answer 1

up vote 2 down vote accepted

Cygwin's zip has the command line switches -F and -FF. They can be used if some portions of the archive are missing.

Use zip -F broken_archive -F --out fixed_archive.zip to create a new ZIP file that contains the same files with hard-fixed CRC, then extract the usual way from the new archive

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Just one question: supposing Cygwin emulates GNU/Linux and "man unzip" reports no -F -FF flags, how am I supposed to use them in Windows? By the way, I have Linux too and I can open files from there. Any advice? –  djechelon Feb 4 '13 at 13:50
    
"man zip" mentions those flags. It also explains how to use them. Basically you use zip -F broken_archive.zip --out fixed_archive.zip –  user570500 Feb 4 '13 at 13:55
    
It looked working just fine. I wasn't lucky: video crashes in the middle but this answer the question anyway –  djechelon Feb 4 '13 at 14:23
    
@djechelon: WinRAR has a Keep broken files extraction option as well. –  Karan Feb 4 '13 at 18:22

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