Merging PDFs

PDFs can be easily merged using GhostScript. The trick is to make GhostScript print a series of PDFs to it's own loopback and then have it write a new PDF, it work like this:

gs -q -sPAPERSIZE=a4 -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=full.pdf parts*.pdf