I want to backup the files i have in Books. The Internet provides me with "~/Library/Containers/com.apple.BKAgentService/Data/Documents/iBooks/Books", but that appear only to be for books from the iBooks Store. Where is everything else located?
Thanks for your reply, and yes, ePubs and PDFs are exactly what I am looking for. Your suggestion was sound, but they're not located there either - I have no Books folder in there.
I think I have to scour through ~/Library/ to see where they hide.. I can't figure out where else they might be..
Edit: Found them! They are in a hidden folder in your iCloud Drive called Books. If you search your home folder for ".epub" or the name of one of the books you can find them, and then right click one and go to the overlaying folder. I couldn't get "~/Library/Mobile\ Documents/com~apple~CloudDocs/Books/" to work, so the above is the only way to access them I guess?