PDF and JPG conversion
PDF files containing scanned JPG files can be converted:
from the folder where the .pdf file is type:
pdfimages -j filename.pdf filename
to extract all jpg files in the same folder.
If you use
pdfimages filename.pdf filename
The output will be ppm files, but that takes a conversion
Put all .jpg files into pdf files:
ls -1 ./*jpg | xargs -L1 -I {} img2pdf {} -o {}.pdf
Combine those .pdf files into one .pdf file:
pdftk *.pdf cat output file.pdf
you may need to install some of these programs first, but the ternminal will tell you so.