xpdf | xpdf with local changes | Document Editor library

After quite a bit of trial and error, I have found a solution that works.

As @mb21 mentioned, Docker image would probably be the best option long term. Docker images are supported on Heroku. However, I wanted to avoid dockerizing the whole application to solve this issue.

After finding a TeX Live buildpack for Heroku that supports adding custom TeX Live packages (one example of such buildpack), the error on conversion was ! LaTeX Error: File 'xcolor.sty' not found.

I used tlmgr to get some info on the missing file. Running tlmgr search --global --file xcolor.sty does the trick and reveals that there is a package called xcolor. After installing that we come to the next error, and the next, and the next. In the end I ended up installing 2 collections that are small enough for Heroku (mind the 500MB slug size limit) and contain everything pandoc needs for a successful conversion. Those 2 are collection-fontsrecommended and collection-latexrecommended.

Adding a texlive.packages file to the root of the application does the trick. It is recognized by the buildpack and it installs all the specified packages for you using tlmgr.

create a docker image where you can grab all required libraries from

This answer is for the case where killall or pkill (suggested in this answer) are not enough for you. For example if you really want to print "xpdf läuft nicht" if there is no pid to kill or applying kill -SIGTERM because you want to be sure of the signal you send to your pids or whatever.

You could use a bash loop instead of xargs and sed. It's pretty simple to iterate over CSV/column outputs:

Recent versions of Ghostscript default to SAFER mode by default, which prevents PostScript programs (like pdf_info.ps) from accessing files in the file system.

In general Ghostscript will try and infer from the command line when files should be permitted (such as the input filename, in the case above pdf_info.ps) but it can't know that -sFile= should be permitted, because that part of the command simply ends up in the PostScript interpreter.

So to use pdf_info.ps you will either have to set -dNOSAFER or add --permit-file-read= to your command line. -dNOSAFER turns off all protection so you may not want to do that, --permit-file-read allows the PostScript program to read the specified directory only. I'd recommend you do that.

I'd also suggest you experiment from the command line using the usual Ghostscript executable and only move to your application when you have it correct.

If you are planning to distribute this application, please have a look at the license file.

There are two fairly simple techniques you can use.

1) Google's "Tessaract" open source OCR (optical character recognition). You could apply this evenly to all PDFs, though converting all that data into pixels and then working magic upon them is going to be more computationally expensive. Which is more important, engineer time or CPU time? There's a pytesseract module. Note that this tool works on image formats, so you'd have to use something like GhostScript (another open source project) to convert all of a PDF's pages to images, then run [py]tessaract on those images.

2) pyPDF can get each page and programmatically extract any text draw operations in the order they were drawn onto the page. This may be nothing like the logical reading order of the page... While a PDF could draw all the 'a's and then all the 'b's (and so forth), it's actually more efficient to draw everything in "font a" , then everything in "font b". It's important to note that "font b" might just be the italic version of "font a". This produces a shorter/more efficient stream of drawing commands, though probably not by such an amount as to be a good business decision to do so.

The kicker here is that a random pile of PDF files might require you to do some OCR. A poorly assembled PDF (one with a font subset that has no "to unicode" data) can't be properly mined for text even though it has nothing but text drawing operations. "Draw glyphs one through five from "font C" doesn't mean much if you don't know that those first five glyphs are "g-l-y-p-h", because that's the order they were used in.

On the other hand, if you've got home-grown PDFs or all your pdfs are from some known source (Word's pdf converter for example), you'll know what to expect in advance.

Note that the only thing mentioned above that I've actually used is Ghostscript. I remember it having a solid command line interface we used to generate images for some online PDF viewer Many Years Ago.

It's a HTML encoding issue. I think you need to either use the following code.

You can append the page number to the name of the PDF file, separated with a hash sign ("#").

To get page 7 of "sample.pdf", use the filename "sample.pdf#6" (zero-based page numbers).

Okay, I figured it out! If you install pdftotext using Anaconda and conda, then importing it seems to only work when you run it in the Python interpreter from within the Anaconda3 shell.

So, I had to switch to the Python interpreter mode in the Anaconda3 PowerShell first: python

Then, I could import pdftotext with no error: import pdftotext

It looked like this: