@JuanGRodeja i think it depends on how the PDF was created whether its easy to search in them or not. If the PDF is basically only an image it gets difficult. Nonetheless possible for example M$ Onenote, does some OCR to let you search in these... That maybe would be a more advanced feature, but for other PDFs, i guess it shouldn't be that difficult. Please open a feature request issue here: https://github.com/ubports/docviewer-app/issues

Thanks. Done.

find $PATH -name '*.pdf' -exec sh -c 'pdftotext "{}" - | grep --with-filename --label="{}" --color "TEXT TO SEARCH FOR"' ;

Where $PATH is the full path you want to search and "TEXT TO SEARCH FOR" is um, the text you want to search for.

In a slightly more elegant way - and as I have - you can use emacs (in my mind, the only way to fully unleash the power of a convergent machine in your pocket!) on UT, install recoll and helm-recoll and then have instant searching through PDFs for text