Watermark all pdfs in folder with the file's name

I have a bunch of pdf files in a folder. I would like to watermark all of them. The watermak should be the name of the file itself. How?

I'm using ubuntu 18.04LTS

Solution 1:

• Create a script gedit /home/user/folderwithpdfs/pdfstamp.sh, which will generate watermark.pdf file with shortened filename's text inside as a watermark:

  #!/bin/bash
  text=${1?missing text to show}
  # Restricts string to 15 symbols from start, without extension and folder's path
  mtext=$(echo ${text:0:15} | sed 's/.pdf//' | sed -e 's,.*/,,') 
  angle=45 # in degrees counterclockwise from horizontal
  grey=0.75 # 0 is black 1 is white
  
  ps2pdf - - <<!
  %!PS
  /cm { 28.4 mul } bind def
  /draft-Bigfont /Helvetica-Bold findfont 72 scalefont def
  /draft-copy {
          gsave initgraphics $grey setgray
          5 cm 10 cm moveto
          $angle rotate
          draft-Bigfont setfont
          ($mtext) show grestore
   } def
  draft-copy showpage
  !
  

• Place it to folder with pdf files

• Run the next command inside the folder with pdf files, which will create watermark.pdf file each time, apply it to current file and output it to the new file:

  for f in ./*.pdf 
    do ./pdfstamp.sh "$f" > watermark.pdf
    pdftk "$f" stamp watermark.pdf output "$f.pdf"
  done
  

  The command will create filename.pdf.pdf files with watermark of file names but without extension and with 15 symbols length.

  Script mostly created by @meuh.

  Result:

  

The next variant of the command will place watermark to the background, so it could look like transparent:

for f in ./*.pdf; do ./pdfstamp.sh "$f" > watermark.pdf && pdftk "$f" background watermark.pdf output "$f.pdf"; done

But this method has a downside: this watermark could be covered over by images.