#!/usr/bin/bash

# Create printable booklet from a scanned book pdf
#
# Here we want to print an A5 size booklet in a way that on the top side of
# each A4 page we print two consecutive odd pages (e.g. 1 and 3), while on
# the other side the two corresponding even pages (4 and 2). Then we send
# the document to the printer with 2 pages per page and two sided printing
# (flip on short edge) settings. The printed A4 pages can be cut precisely
# in the middle into A5 size with a paper cutting tool. Finally, we bind
# the A5 pages together to form a booklet.
#
# To create a pdf with a page order suitable for this kind of printing, we
# use pdftk (PDF Toolkit), a simple and efficient command line tool for pdf
# manipulation. The tool is available from the web page below or from most
# of the Linux package repositories.
#
# https://www.pdflabs.com/tools/pdftk-the-pdf-toolkit/
#
# Once we have pdftk installed, it takes only two commands to reorder the
# pages. First we sort the even and odd pages into separate files. Then we
# merge these files in a way that we take 2 pages from the odd pages, and
# 2 from the even but in reversed order.

pdftk original.pdf cat 1-endeven output even.pdf
pdftk original.pdf cat 1-endodd output odd.pdf
pdftk A=odd.pdf B=even.pdf shuffle Aodd Aeven Beven Bodd output booklet.pdf