OCLC does not currently publish a reconciliation report of new items placed on hold (the Daily Holds Ready for Pickup report is a cumulative list). We'll need to keep a list of previously added items to diff out the new from the old. This uses LevelDB to store a list of hashed ND-JSON objects and only passes unique items through.
Pipe a stream of ND-JSON objects
$ unique-holds < holds-list-20160229.txt > new-holds-20160229.txt
Note: you'll have to do this once to prime the db with items to ignore.