This script was inspired by the Stack Exchange question, Is there someway to get a list of all missing photos from the photo library?
I had the same question, and it turns out that the photo library is backed by a SQLite database under the covers. You can find it at <photo library root>/database/photos.db. There's a table called RKMaster, with a row for every photo, and a column called fileIsReference that tells you whether the photo is "external" or not. It's relatively straightforward to script a solution from there.
The script does not require any parameters. You can simply run:
./find-missing-photo-referencesIf it finds any broken links, then it will produce output like the following:
/Users/msolnit/Pictures/beach.jpg is missing.
/Users/msolnit/Pictures/cow.jpg is missing.
/Users/msolnit/Pictures/kitten.jpg is missing.
If there are no broken links, then the script is silent (does not produce any output).
The photos.db schema is not part of any public Apple documentation, so this script may break any at any time due to minor (or major) software updates. No guarantees are made about its safety, etc. etc. But it works fine for me.