Adding metadata/keywords to pdf

The Automator Set PDF Metadata action will set quoted PDF keywords if you enter them with double-quotes, and without if you exclude the quotes. Just tested this again on macOS 11.6.1 with an existing PDF. Get Info showed double-quotes on the keyword I set with them, and without double-quotes on the keyword without. This was verified when using ExifTool to list the keywords just placed on that PDF.

Continued.

Automator also has a PDF action named Get PDF Metadata, where one can just select Keywords in it and let that fall through into a Set Value of Variable action named existing_keywords. However, one is thwarted from adding this variable to the Keywords section of the Set PDF Metadata action in an effort to keep existing Keywords and then optionally adding any additional.

The key to keeping existing Keywords with the preceding Automator workflow is to not select Keywords in Set PDF Metadata.

If you want to keep existing, and potentially add new keywords to a PDF, then you will need a third-party PDF Editor to do that reliably.

Apple's Automator has a Set PDF Metadata action that allows you to apply the following content to a selected PDF which is updated in place in its original location. This is an Automator application that you would save to your Desktop and double-click to prompt for the PDF:

and a Finder's Get Info on that PDF reflects all of the metadata written to it:

There was already a keyword on the PDF I tested with this workflow and it was overwritten when I chose additional Keywords from the Automator action. Although Apple's Preview's Inspector panel allows you to set, add, or remove PDF keywords, these do not update or replace the existing PDF keywords as one would expect.

I've tried using the Set Pdf Metadata Action but it always seems to add Quotations ( " ) to the start and end of the Keywords ? any idea how to stop this, other than a script ?

The most comprehensive command-line tool for writing metadata is ExifTool. There is a steep learning curve. It can write keywords to pdfs, but my understanding from the PDF Tags page is that they are structured as a comma-delimited string, not as individual fields. There's a friendly and active forum where you could pick up more detail.

Cheers,

H

Not PDF Tags, but PDF keywords:

# add two keywords to a PDF
exiftool -PDF:keywords+="Ant,Aardvark" foo.pdf
# list keywords on the PDF
exiftool -s3 -PDF:keywords foo.pdf
Ant
Aardvark
# remove one keyword
exiftool -PDF:keywords-="Ant" foo.pdf
# list keywords
exiftool -s3 -PDF:keywords foo.pdf
Aardvark