You can save this in a file called query.js and then execute it with mongo localhost:27017/mydb query.js
It will output something like
[ { "_id" : ObjectId("5547ae6a65190fe21225ec2b"), "_key" : "post:124", "pid" : 124, "uid" : 47, "tid" : 5, "content" : "I like it too :)", "timestamp" : 1376791225638, "bookmarks" : 2 }, { "_id" : ObjectId("5547aee765190fe212296f10"), "_key" : "post:18", "pid" : 18, "uid" : 2, "tid" : 5, "content" : "Thank you :)", "timestamp" : 1373686442781 } ]
