Process a PDF to allow for half-size booklet printing

half-size-booklet.sh

# Get the number of pages in the PDF. (On a Mac you can do `pages=$(mdls -raw -name kMDItemNumberOfPages $PDF)`)
pages=$(pdftk $PDF dump_data | grep NumberOfPages | awk '{print $2}')
# Get the number of 16-page booklets
booklets=$(($pages/16))
if [[ $(($pages%16)) -gt 0 ]]; then
    booklets=$(($booklets+1))
fi
# Determine where to split the book for the half-size
booksplit=$(($booklets/2))
# Determine at what page to split the book
pagesplit=$(($booksplit*16))
# Determine the page number for the extra booklet, if any
extrabooklet=0
if [[ $(($booklets%2)) -gt 0 ]]; then
    extrabooklet=$(($pagesplit*2+1))
fi
# Split the PDF into 2 parts
pdftk $PDF cat 1-$pagesplit output split-top.pdf
pdftk $PDF cat $(($pagesplit+1))-$(($pagesplit*2)) output split-bottom.pdf
# Insert blank pages on the bottom to make sure page numbers are equal
echo '\shipout\hbox{}\end' | pdftex # Creates 'texput.pdf'
# Create a 16-page PDF of blank pages
pdftk texput.pdf cat 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 output blank.pdf
# Determine if we need an extra booklet or to pad the last booklet
if [[ $extrabooklet -gt 0 ]]; then
    pdftk $PDF cat $extrabooklet-$pages output extra.pdf
    extrapages=$(($pages-$extrabooklet))
    pdftk blank.pdf cat 1-$extrapages output blank-cut.pdf
    pdftk A=extra.pdf B=blank-cut.pdf shuffle A B output extra-shuffle.pdf
    pdftk A=extra-shuffle.pdf B=blank.pdf cat A B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 output extra-extended.pdf
    pdftk extra-extended.pdf cat 1-32 output extra-booklet.pdf
    rm extra.pdf blank-cut.pdf extra-shuffle.pdf extra-extended.pdf
else
    # Add 15 blank pages to the end, then cut the pages back to the right number
    pdftk A=split-bottom.pdf B=texput.pdf cat A B B B B B B B B B B B B B B B B output split-bottom-extended.pdf
    pdftk split-bottom-extended.pdf cat 1-$pagesplit output split-bottom.pdf
    rm split-bottom-extended.pdf
fi
# Collate the two parts
pdftk A=split-top.pdf B=split-bottom.pdf shuffle A B output collated.pdf
# Add the extra booklet to the end if necessary
if [[ $extrabooklet -gt 0 ]]; then
    pdftk A=collated.pdf B=extra-booklet.pdf cat A B output collated-extra.pdf
    mv collated-extra.pdf collated.pdf
    rm extra-booklet.pdf
fi
# Arrange 2 logical pages vertically on a single page
pdfjam collated.pdf --nup 1x2 --no-landscape --papersize '{8.5in,22in}' --outfile output.pdf
# Delete our temporary files
rm split-top.pdf split-bottom.pdf texput.pdf texput.log blank.pdf collated.pdf