https://docs.mongodb.com/v3.2/reference/mongo-shell/
show dbs
show databases
show collections
db.runCommand("serverStatus")
db.runCommand({ serverStatus: 1 })
db.runCommand("dbStats")
db.runCommand({ dbStats: 1 })
db.runCommand("whatsmyuri")
db.runCommand({ whatmyuri: 1 })
db.runCommand({ "collStats": "<collection name>"})
db.<collection>.find(<query>)
db.<collection>.findOne(<query>)
db.<collection>.count()
db.<collection>.find(<query>).count()
db.<collection.find().sort().skip().limit()