Program to add a blank page if PDF has an odd number of pages

Question

I'm looking for a program that can:

• add a blank page if the PDF has an odd number of pages (no action if the PDF has an even number of pages). It must be able to process several PDFs at once. (otherwise I can just do it manually)

And if possible (descending priority):

• works on Windows 7
• easy to use
• free

---

User story: I have to print 30 PDFs. Due to my university printing system, every time a document is sent to the printer a dialog box pops up to ask to which user ID I want to print the document. In order to avoid getting this dialog box 30 times, I want to combine those 30 PDFs into one PDF. The issue is when I print the combined PDF, sometimes the first page of the initial PDFs is located on the verso of a page, which makes it impossible to staple the printed PDFs one by one.

Answer 1

The idea is from this answer on stackoverflow. But as you are a Windows user, I doubt that shell scripts will work for you. So I've implemented a Python version that should also work on Windows.

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 uniprint.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 uniprint.py executable

Every time you need it

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

Python

#!/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

You can use PDFsam:

• gratis
• runs on Microsoft Windows, Mac OS X and Linux
• portable version available (at least on Windows)
• can add a blank page after each merged document if the document has an odd number of pages

Answer 3

You could use PDFtk to merge the documents, and have a one-blank-page pdf file, that you could insert after every document with and odd number of pages. It will be 5 minutes to create a single PDF with 30 documents merged (you can add all the files at once).

As you can see the number of pages of every document, its easy adn fast to do. An example:

Maybe it's not the solution you are looking for, but a workaround.

Answer 4

There is a program called A PDF Merger.

Does exatcly what you ask:

1. Add all the files
2. Go to Options → Pages → add a blank page for odd numbers

It’s free to try with a watermark only on the first page but you can get it free as well.