Step 1 is to dd the whole USB drive to a backup image. Then from a copy of
that backup image you can start trying recovery from that.

On Sun, Jan 12, 2020 at 1:32 PM Keith Lofstrom <[email protected]> wrote:

> The three book scanners near the checkout desk at the
> PSU Millar library are somewhat difficult to use, but
> better than my slow USB flatbed scanner at home.
>
> Yesterday I scanned three huge multipage files to a
> Brand X "Cheap on Amazon" 2GB USB flash drive.  I was
> in a hurry,  so I did not segment the files into smaller
> chunks, or check the files with my laptop as I made them.
>
> Bad idea.
>
> I now have a flash drive which is 60% full, but no files
> are listed in the directory.  Either the files were too
> large for the scanner, or the 40 character file names were.
> The flash drive is formatted for VFAT16 DOS or somesuch.
>
> I hope to recover the files (if not the file names) and
> avoid another 90 minute, 200+ page scanning marathon.
> I can grep the drive image for strings; I don't see the
> filenames, but grep shows about 100 strings like
> /ProcSet [ /PDF /ImageB ] -or-f /ProcSet [ /PDF /ImageC ]
> and some fragments.  I tried using "testdisk" tools to
> recover the three files; no joy.
>
> My best guess is that my overly-long scan files blew
> the memory buffer on the PSU scanner, and it overwrote
> garbage.  There are signs above the scanners to "save
> frequently" which I ignored (https://www.xkcd.com/293/)
>
> PERHAPS SOMEONE CAN SUGGEST CLEVER TOOLS to extract the
> pdfs from the 1.2 gigabytes of "unlabeled something" on
> the flash drive.  Knowing how might help me help others
> in the future.
>
> I expect I will only get my files by scanning them
> again, properly, in small chunks PSU's feeble scanners
> can handle.  Meanwhile, "don't do that" is probably the
> most help I can offer to others.
>
> Keith
>
> P.S. - the best book scanner I've used was at MIT Barker
> Library; it images the book open 120 degrees, face up,
> and accomodates the natural curve of the pages.  The book
> scanners in the Library of Congress are almost as good,
> but you must stretch the pages flat to get focused images.
>
> --
> Keith Lofstrom          [email protected]
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