[chaley]

"Find books with missing files" searches for books CC's database but where the ebook files have been removed from the file system. After getting a list such books, you can remove the book's record, or metadata, from CC's database, individually or all of them.

This function is needed because unless the book was deleted using CC or calibre, CC will still has a record of the book and will think that the file is still there. The function tells CC to do a bit of housekeeping. This housekeeping is done on user request (the Find books with missing files command) to avoid slowing CC down for something that should not happen often.