Converting PDFs to Greyscale
Needed to remove the colour from PDFs that were too big to print our our crappy printer.
find . -iname '*.pdf' -exec sh -c 'gs -sOutputFile=grey/{} -sDEVICE=pdfwrite -sColorConversionStrategy=Gray -dProcessColorModel=/DeviceGray -dCompatibilityLevel=1.4 -dNOPAUSE -dBATCH {}' \;
Greyscale will print much better, although the colour versions look amazing.