Batch remove comments from PDF files

How can I easily remove all comments and annotations (added with Foxit Reader) from all the PDFs in a folder?

I just came across this problem, and none of the answers given here worked for me. What did work was the rewritepdf tool from the Ubuntu package libcam-pdf-perl:

rewritepdf -C in.pdf out.pdf

Wrapping this into a little scripting to remove annotations from all pdf files in a directory is now easy:

for i in *.pdf; do rewritepdf -C '$i' '$i'.new; done

As usual, you can install libcam-pdf-perl via the Software Center or using sudo apt install libcam-pdf-perl

Providing you're on a Unix system:

cd <directory containing PDFs>
find . -type f -name '*.pdf' -exec perl -pi -e 's:/Annots \[[^]]+\]::g' {} +

This is a hack that removes all /Annots commands from the PDF (the commands that draws the annotations). It leaves the annotation objects there (you can open the PDF with a text editor and search for them), they're just not drawn.