I am officially an old person, as I have subscribed to a magazine. It’s niche, but it’s been around a long time, and having enjoyed a lot of issues in my childhood that were given to me for free, I feel I should give back.

I’m wondering if there are precautions I should take. Can any sort of copy protection be put into PDFs that I should strip out? If I share them as a torrent, should I be worried that the publisher can tell where they came from?

  • GenderNeutralBro@lemmy.sdf.orgEnglish
    17·
    11 months ago

    There are some free, open-source command line tools that can do this.

    First off, there’s exiftool. It’s the go-to utility to read and write metadata in a wide variety of file types, like mp3, jpg, and you guessed it, pdf. It’s very easy to use:

    To read all the metadata in a file: exiftool -a -All <file> (where <file> is the path to your pdf).

    To erase all the metadata in a file: exiftool -a -All="" <file> (that’s two double-quotes, to indicate a blank string). Please note that this will overwrite your file in-place! If you want to save the output as a new file, use exiftool -a -All="" -o <output_file> <file>.

    exiftool is likely all you need for your use case, but if you need more advanced PDF manipulation, with a truly dizzying array of options, there’s Ghostscript. Ghostscript can read, write, and convert PDFs, and provides hooks to apply any PostScript commands and options.

    To simply print out information on a PDF file: gs -dPDFINFO -dBATCH <file>. This will show you the metadata, such as author, title, etc.

    I’m…not going to give you an example of how to use Ghostscript to edit metadata because I’m not confident I’d get it right. The gist is that you use PostScript commands with the -c flag. It is truly arcane but extraordinarily powerful.

    If you’re on Linux, you can likely get both of these with your distro’s default package manager. On Mac, use Homebrew or MacPorts. On Windows, you can download prebuilt binaries from their web sites. I think you can even run them on Android using Tmux Termux.

    • drivepiler@lemmy.worldEnglish
      9·
      11 months ago

      I believe you’re referring to Termux, the terminal app. Tmux is a terminal multiplexer. Although you can run Tmux in Termux, so technically…

      Anyway, great post! It seems I have to check out Ghostscript, don’t think I’ve ever heard of it, thanks.

  • Atropos@lemmy.worldEnglish
    16·
    11 months ago

    I think if you print the PDF to another PDF, it’ll lose any copy protection or potential identifiers.

      • Daniel Quinn@lemmy.caEnglish
        16·
        11 months ago

        The easiest way to confirm this would be:

        1. Find out how to list the metadata from a PDF.
        2. List the metadata from a known-to-have-stuff-you-don’t-want PDF.
        3. “Print” the new PDF from the old one
        4. List the metadata from the new PDF.
        • Timwi@kbin.social
          19·
          11 months ago

          This obviously assumes that you know exactly what metadata you want to eliminate and how to view it.

          The OP’s whole point of asking is that they don’t know the former.

          • sebinspace@lemmy.worldOPEnglish
            8·
            11 months ago

            This, essentially. Like until I tried to move music from iTunes to Foobar, I didn’t learn that metadata was even a thing, and apparently neither does Apple.

      • amigan@lemmy.dynatron.meEnglish
        3·
        11 months ago

        If you use ghostscript, it absolutely should, but you’re probably better off using something like cpdf.

    • doc@kbin.social
      3·
      11 months ago

      Adobe and Microsoft PDF printers retain some information. If you run it through ghostscript you’ll get only the PostScript output. You can use a free utility like cutepdf to make it easy. Just install the latest gs release after installing cutepdf instead of the download they provide.

  • refutablewife@reddthat.comEnglish
    9·
    11 months ago

    Use calibre book converter. You might need a plugin if it’s a super specific drm that needs to be removed (like, say, a library book from the libby app), but calibre will let you pick any output you want and save it as a clean file.

    • Radin@lemmy.worldEnglish
      1·
      11 months ago

      I’ve used calibre to put ebooks on my kindle before but do you have any idea if that would work for books downloaded from kindle unlimited? It’d be great to grab a bunch on my “to read” list and not have to worry about reading them before my subscription runs out.

      • refutablewife@reddthat.comEnglish
        2·
        10 months ago

        Yeah, for sure

        1. download it to kindle 2: transfer azw/mobi file to computer 3: open calibre and install DeDRM 4: drag and drop books into calibre 5: calibre is auto de-drm’ing the books so you can now convert them to any format you want or just backup the books