====== Merge many JPG-Files into a single PDF ======
30.12.2014

  sudo apt install imagemagick

Again we use here imagemagick in a very simple form:
  convert *.jpg output.pdf

====== Merge many PDF-Files into a single PDF ======
  pdfunite *.pdf out.pdf

Or by using PDF-Shuffler
  sudo apt install pdfshuffler