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
