How can I merge PDF files (or PS if not possible) such that every file will begin in a odd page?

Question

I am working on a UNIX system and I\'d like to merge thousands of PDF files into one file in order to print it. I don\'t know how many pages they are in advance.

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Answer 1

Preparation

1. Install Python and make sure you have the pyPDF package.
2. Create a PDF file with a single blank in /path/to/blank.pdf (I've created blank pdf pages here).
3. Save this as pdfmerge.py in any directory of your $PATH. (I'm not a Windows user. This is straight forward under Linux. Please let me know if you get errors / if it works.)
4. Make pdfmerge.py executable

Every time you need it

Run uniprint.py a directory that contains only PDF files you want to merge.

pdfmerge.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from argparse import ArgumentParser
from glob import glob
from pyPdf import PdfFileReader, PdfFileWriter

def merge(path, blank_filename, output_filename):
    blank = PdfFileReader(file(blank_filename, "rb"))
    output = PdfFileWriter()

    for pdffile in glob('*.pdf'):
        if pdffile == output_filename:
            continue
        print("Parse '%s'" % pdffile)
        document = PdfFileReader(open(pdffile, 'rb'))
        for i in range(document.getNumPages()):
            output.addPage(document.getPage(i))

        if document.getNumPages() % 2 == 1:
            output.addPage(blank.getPage(0))
            print("Add blank page to '%s' (had %i pages)" % (pdffile, document.getNumPages()))
    print("Start writing '%s'" % output_filename)
    output_stream = file(output_filename, "wb")
    output.write(output_stream)
    output_stream.close()

if __name__ == "__main__":
    parser = ArgumentParser()

    # Add more options if you like
    parser.add_argument("-o", "--output", dest="output_filename", default="merged.pdf",
                      help="write merged PDF to FILE", metavar="FILE")
    parser.add_argument("-b", "--blank", dest="blank_filename", default="blank.pdf",
                      help="path to blank PDF file", metavar="FILE")
    parser.add_argument("-p", "--path", dest="path", default=".",
                      help="path of source PDF files")

    args = parser.parse_args()
    merge(args.path, args.blank_filename, args.output_filename)

Testing

Please make a comment if this works on Windows and Mac.

Please always leave a comment if it doesn't work / it could be improved.

It works on Linux. Joining 3 PDFs to a single 200-page PDF took less then a second.

Answer 2

The code by @Chris Lercher in https://stackoverflow.com/a/12761103/1369181 did not quite work for me. I do not know whether that is because I am working on Cygwin/mintty. Also, I have to use qpdf instead of pdftk. Here is the code that has worked for me:

#!/bin/bash

for f in *.pdf; do
  npages=$(pdfinfo "$f"|grep 'Pages:'|sed 's/[^0-9]*//g')
  modulo=$(($npages %2))
  if [ $modulo -eq 1 ]; then
    qpdf --empty --pages "$f" "path/to/blank.pdf" -- "aligned_$f"
  else
    cp "$f" "aligned_$f"
  fi
done

Now, all "aligned_" files have even page numbers, and I can join them using qpdf (thanks to https://stackoverflow.com/a/51080927):

qpdf --verbose --empty --pages aligned_* -- all.pdf

And here the useful code from https://unix.stackexchange.com/a/272878 that I have used for creating the blank page:

echo "" | ps2pdf -sPAPERSIZE=a4 - blank.pdf