On Wed, Feb 1, 2023 at 11:45 AM Fred Cisin via cctalk <cctalk@classiccmp.org>
wrote:

> On Wed, 1 Feb 2023, Zane Healy via cctalk wrote:
> > So far I’ve tackled one split zip.  I wasn’t having any luck with
> > the version of PKZIP that I assume created this.  I copied the files
> > into a directory, and did COPY
> > FILE1.ZIP+FILE2.ZIP+FILE3.ZIP+FILE4.ZIP+FILE5.ZIP COMBINED.ZIP
>
> THAT will give you a corrupted file!
>
> Concatenated copy (COPY with '+') has a behavior that you need to take
> into account.
>
> PC/MS-DOS 1.00 kept track of the file size with a course granularity.
> (logical sectors, not bytes)
> Therefore, PC/MS-DOS supported CTRL-Z as an end of file character!
> (A legacy of CP/M)
>
> When you cop a file, it copies the whole thing.  Any extraneous content
> after EOF won't matter.
>
> BUT!  When you concatenate files,
> COPY FILE1.ZIP + FILE2.ZIP COMBINED.ZIP
> COPY will terminate FILE1.ZIP at the first CTRL-Z that it encounters!
> When copying text files, Concatenated COPY will trim off all content after
> EOF!
> It is called "text mode".
>
> You need to change your command to
> COPY /B  FILE1.ZIP+FILE2.ZIP+FILE3.ZIP+FILE4.ZIP+FILE5.ZIP COMBINED.ZIP
> to get "binary mode", so that it will copy ALL of each file, rather than
> just to the "end of file character" of each!
>
> Compare the final resulting file size of  COPY and COPY /B
>
> --
> Grumpy Ol' Fred                 ci...@xenosoft.com


Excellent knowledge transfer, Fred.  That is what makes this list great.

Sellam

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