mongodb-setup.js

    var mongo = require('mongodb').MongoClient
    var age = process.argv[2]
    
    var url = 'mongodb://localhost:27017/learnyoumongo'
    
    mongo.connect(url, function(err, db) {
      if (err) throw err
      var parrots = db.collection('parrots')
      parrots.find({
        age: {
          $gt: +age
        }
      }).toArray(function(err, docs) {
        if (err) throw err
        console.log(docs)
        db.close()
      })
    })