Two Ways to Merge PDFs

TL;DR

Here’s how you merge two PDF documents together.

pdfunite

Merge two documents:

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pdfunite file1.pdf file2.pdf mergedfile.pdf

pdftk

Merge one document with odd pages, and one document with even pages into one sequential file:

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pdftk A=odd.pdf B=even.pdf shuffle A B output merged.pdf

The Rest of the Story

Do you only have a one-sided scanner? Have you ever needed merge two PDF scans together? Here are a couple options for you if you are using Linux.

In my scenario, these commands work on Linux Mint 19.1, but I’ll wager that they will work on most if not all Linux distributions (especially the snap package).

Merge

First I’ll handle the simple scenario of merging file1.pdf with file2.pdf. For that we’ll use pdfunite. Pdfunite came installed with Linux Mint. To use it simply open up the terminal, and follow this pattern:

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pdfunite file1.pdf file2.pdf mergedfile.pdf

You can merge as many documents as you want. You could do:

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pdfunite file1.pdf file2.pdf file3.pdf mergedfile.pdf

Or:

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pdfunite file1.pdf file2.pdf file3.pdf file4.pdf mergedfile.pdf

Hopefully, you get the idea ;-) The very last file name in the series will be the merged file, or the output file. So simply enter the command, then a file name, a space, another file name, a space, etc., and finally the name of the file you want to create.

Here are some more details for the pdfunite command: http://manpages.ubuntu.com/manpages/bionic/man1/pdfunite.1.html

Mixed

Ok, now what if, for example, you only have a one-sided scanner? You now have to scan two-sided documents twice, and that gives you a scan set of odd pages, and a scan set of even pages. Ultimately, you want those to be one sequential document just like the original documents, well there’s an app for that too.

The app is called pdftk. This did not come pre-installed with Linux Mint. So, if you try to run pdftk from the terminal, you get this error:

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sudo apt install snapd
sudo snap install pdf

If you do have Snappy installed, here are the commands to get pdftk installed:

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sudo snap install pdf

Once installed, here is the command to take a scan of odd pages, a scan of even pages, and merge them into one sequential PDF:

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pdftk A=odd.pdf B=even.pdf shuffle A B output merged.pdf

In the command above, I actually renamed my file with the odd pages “odd.pdf”, and likewise with the even-paged document. The “merged.pdf” is the file you want to create. Originally, I found the info for pdftk on StackExchange.

And that’s it, that’s all you need to do. Hope you find this helpful!

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