How to run pdftotext ... | grep on many documents?

Code which works with a single document pdftotext *.pdf - | grep therapy You can use find as described in the thread How can I grep in PDF files? but I would like to understand why the above command is not working. Differential code where pdfgrep may add some benefit but still early in development pdftotext *.pdf - | pdfgrep therapy #Wrong syntax so error # Usage: pdfgrep [OPTION]... PATTERN FILE... # Syntax Warning: Invalid Font Weight # Syntax Warning: Invalid Font Weight I would like to get then a fast way to move to the specific pdf page if there is a good match. However, I have not found any evidence that such a feature exists. OS: Debian 8.5 Linux kernel: 4.6 backports Hardware: Asus Zenbook UX303UA Poppler-utils: pdftotext