To start:
https://prepression.blogspot.com/2016/08/extracting-metadata-to-csv.html
https://community.adobe.com/t5/photoshop-ecosystem-discussions/script-to-change-name-of-document-to-its-size-tag-and-save-overwrite/td-p/11736503
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Edit: I just updated the previously mentioned blogpost to include the script from Mars Premedia and now Blogger has disabled the post! Here it is in full for now...
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There are five common methods for extracting/exporting metadata from one or more files to a comma separated value (.csv) or tab delimited text file.
Adobe Bridge Script – Extract Metadata, by Paul Riggott:
https://www.ps-scripts.com/viewtopic.php?f=72&t=24358&sid=6529114a378b6e37ff888bf74ba105cf
Adobe Bridge Script – Barred Rock Script “BSExportMetadata”:
http://creativescripting.net/blog/2009/01/free-stuff/ or
https://metadatatocsv.wordpress.com/scripts/
Adobe Bridge Script – VRA Panel Export-Import Tool
http://metadatadeluxe.pbworks.com/w/page/48025141/VRA%20Panel%20Export-Import%20Tool
Adobe Photoshop Script – Images Report, by Mars Premedia
https://www.marspremedia.com/software/photoshop/images-report
ExifTool – by Phil Harvey:
http://www.sno.phy.queensu.ca/~phil/exiftool/
http://www.sno.phy.queensu.ca/~phil/exiftool/exiftool_pod.html
An example of using ExifTool to write all metadata to a .csv file on the desktop using the source directory titled “test” on the desktop (the following code would be entered into Terminal.app on the Mac or the Command Prompt in MS Windows):
exiftool -r -all -csv '/Users/loggedinusername/Desktop/test' > '/Users/loggedinusername/Desktop/metadata-out.csv'
This code is formatted for the Mac OS, MS Windows would use straight double quote marks “ and the expected \ file path formatting.
Of course, the flipside of exporting metadata is to import metadata, which is also a feature of ExifTool. For an Adobe Bridge solution, try the VRA Panel Export-Import Tool or Paul Riggott’s Do It Yourself Metadata Input script (also here) and for Photoshop there is Keywords from CSV from Mars Premedia.