generate_printable_pdf.bash

#!/bin/bash

# Usage:
# ./this_script.bash -i [input file] -o [output file]
# generate a PDF that can be directly printed from an E-book

pdf_file=""
temp_dir="temp"
output_file=""

while getopts 'i:o:' opt; do
	case $opt in
		i)
			pdf_file="$OPTARG"
			;;
		o)
			output_file="$OPTARG"
			;;
		*)
			exit 1
			;;
	esac
done

# both arguments are required
[ -z "$pdf_file" -o -z "$output_file" ] && exit 1



pdf_page_count="$(pdfinfo "$pdf_file" | grep '^Pages:' | awk '{print $2}')"
# including empty pages
book_page_count="$(( ($pdf_page_count + 3) / 4 * 4 ))"

pdfnup_arg=""
for i in $(seq $(( $book_page_count / 2 ))); do
	neighbor_page=$(( $book_page_count + 1 - $i ))
	if [[ "$neighbor_page" -gt "$pdf_page_count" ]]; then
		neighbor_page="{}"
	fi

	if [[ "$(( $i % 2 ))" == 0 ]]; then
		left_page="$i"
		right_page="$neighbor_page"
	else
		left_page="$neighbor_page"
		right_page="$i"
	fi

	if [[ -z "$pdfnup_arg" ]]; then
		pdfnup_arg="$left_page,$right_page"
	else
		pdfnup_arg+=",$left_page,$right_page"
	fi
done

# TODO: automatically set paper size according to original pdf file
pdfnup "$pdf_file" "$pdfnup_arg" -q --outfile "$output_file"