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Extracting Multisegment Zip Archives

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  Extracting Multisegment Zip Archives Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-19 01:20 +0000
    Re: Extracting Multisegment Zip Archives c186282 <c186282@nnada.net> - 2025-12-19 02:41 -0500
      Re: Extracting Multisegment Zip Archives John Ames <commodorejohn@gmail.com> - 2025-12-19 08:05 -0800
    Re: Extracting Multisegment Zip Archives jayjwa <jayjwa@atr2.ath.cx.invalid> - 2025-12-19 20:20 -0500
      Re: Extracting Multisegment Zip Archives Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-20 02:47 +0000
      Re: Extracting Multisegment Zip Archives rbowman <bowman@montana.com> - 2025-12-20 06:15 +0000

#79454 — Extracting Multisegment Zip Archives

This page
<https://open3dlab.com/project/cba26de0-d1ee-4daa-abbb-00fb16a75358/>
contains some multipart archives in .zip and .7z format.

Try as I might I could not use zip and unzip to make any sense of the
multipart .zip, .z01 etc files. There were suggestions in the man page
to concatenate them together and use the -Z or -ZZ options to fix them
up, but all I got was failure.

Finally I discovered that 7-zip can not only extract its own multipart
archives, it can handle .zip ones as well. Painlessly.

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#79472

On 12/18/25 20:20, Lawrence D’Oliveiro wrote:
> This page
> <https://open3dlab.com/project/cba26de0-d1ee-4daa-abbb-00fb16a75358/>
> contains some multipart archives in .zip and .7z format.
> 
> Try as I might I could not use zip and unzip to make any sense of the
> multipart .zip, .z01 etc files. There were suggestions in the man page
> to concatenate them together and use the -Z or -ZZ options to fix them
> up, but all I got was failure.
> 
> Finally I discovered that 7-zip can not only extract its own multipart
> archives, it can handle .zip ones as well. Painlessly.

   7-Zip *is* the improved utility.

   Multi-parts ... try deliberately shifting to the dir
   where  all the parts are stored and THEN running it.

   Alas, I've yet to find a way to get 7z to use more
   advanced encryption methods. ZIP encryption is kinda
   crappy, many pw busters out there for it.

   Got well into corporate backup methods back in the
   day. Could NOT find anything I liked. So, wrote my
   own. Each individual file could be zipped or not
   and then put through AES encryption. Gotta zip BEFORE
   encryption btw or you get big fat files - encrypted
   files are binary 'white noise' and zippers can't zip.

   Also, for safety, did all the encryption LOCALLY in
   a temp dir before sending the files to local, or
   especially 'cloud', storage. I do NOT trust 'cloud
   storage' providers ... esp not NOW when there is
   big $$$ selling content to AI companies as 'training
   material'.

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#79497

On Fri, 19 Dec 2025 02:41:51 -0500
c186282 <c186282@nnada.net> wrote:

> Each individual file could be zipped or not and then put through AES
> encryption. Gotta zip BEFORE encryption btw or you get big fat files
> - encrypted files are binary 'white noise' and zippers can't zip.

Did that back at another job, some years ago - the client IIRC was a
fleet-services payment processor, so we dealt with sensitive customer
info at fairly high $ amounts, but either their backend or ours was too
antiquated for more secure methods, so payment info was sent in a plain-
text spreadsheet that we zipped up, PGPed, and...sent over unencrypted
FTP :/

(Hoo boy were we not PCI-compliant at that place - we'd brought on a
guy for compliance years before, but he was one of the most dedicatedly
useless people I've ever had the displeasure to work with. When I got
laid off we *still* weren't compliant, and since he was axed as well I
imagine they never were. To nobody's surprise, the company folded a few
years later.)

When the client got paranoid about that setup, we ended up *printing
out and mailing* the spreadsheets o_O

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#79535

Lawrence D’Oliveiro <ldo@nz.invalid> writes:

> Finally I discovered that 7-zip can not only extract its own multipart
> archives, it can handle .zip ones as well. Painlessly.
Yup. Pretty handy, especially when you need to send files to people on
other platforms and also when you don't want the metadata to go along
with it. Hopefully you have the full one that used to be Windows-only
and not the p7zip one? If you can, get the little assembler it wants to
build. That version is much faster than the one built without.

7-Zip (z) 24.09 (x64) : Copyright (c) 1999-2024 Igor Pavlov : 2024-11-29
 64-bit locale=en_US.utf8 Threads:8 OPEN_MAX:1024, ASM

It should say "ASM" at the end, as above.

-- 
PGP Key ID: 781C A3E2 C6ED 70A6 B356  7AF5 B510 542E D460 5CAE
       "The Internet should always be the Wild West!"

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#79536

On Fri, 19 Dec 2025 20:20:36 -0500, jayjwa wrote:

> Hopefully you have the full one that used to be Windows-only
> and not the p7zip one?

Standard Debian package.

<https://packages.debian.org/trixie/7zip>

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#79544

On Fri, 19 Dec 2025 20:20:36 -0500, jayjwa wrote:

> 7-Zip (z) 24.09 (x64) : Copyright (c) 1999-2024 Igor Pavlov : 2024-11-29
>  64-bit locale=en_US.utf8 Threads:8 OPEN_MAX:1024, ASM

fwiw. Fedora and Ubuntu have 

7-Zip 25.01 (x64) : Copyright (c) 1999-2025 Igor Pavlov : 2025-08-03
 64-bit locale=en_US.UTF-8 Threads:8 OPEN_MAX:1024, ASM


Linux Mint 22.2 is 23.01 without the ASM.

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