MongoDB Command Examples

February 12, 2020

MongoDB Installation on Mac

You can run MongoDB as a macOS service using brew, or you can run MongoDB manually as a background process. It is recommended to run MongoDB as a macOS service, as doing so sets the correct system ulimit values automatically (see ulimit settings for more information).

To run MongoDB manually as a background process, issue the following:

mongod --config /usr/local/etc/mongod.conf --fork

Run mongoDB in the foreground

mongod --config /usr/local/etc/mongod.conf

cat /usr/local/etc/mongod.conf
  destination: file
  path: /usr/local/var/log/mongodb/mongo.log
  logAppend: true
  dbPath: /usr/local/var/mongodb

Alternatively, to run MongoDB as a macOS service, issue the following (the process uses the /usr/local/etc/mongod.conf file, created during the install):

brew services start mongodb-community@4.2

Tais-MBP:birdboard tailu$ brew services start mongodb-community@4.2
==> Tapping homebrew/services
Cloning into '/usr/local/Homebrew/Library/Taps/homebrew/homebrew-services'...
remote: Enumerating objects: 27, done.
remote: Counting objects: 100% (27/27), done.
remote: Compressing objects: 100% (19/19), done.
remote: Total 27 (delta 0), reused 16 (delta 0), pack-reused 0
Unpacking objects: 100% (27/27), done.
Tapped (65 files, 69.2KB).
==> Successfully started `mongodb-community` (label: homebrew.mxcl.mongodb-community)

To verify that MongoDB is running, search for mongod in your running processes:

ps aux | grep -v grep | grep mongod

Tais-MBP:birdboard tailu$ ps aux | grep -v grep | grep mongod
tailu            59126   0.0  0.2  5592684  41400   ??  S     5:37AM   0:01.05 /usr/local/opt/mongodb-community/bin/mongod --config /usr/local/etc/mongod.conf

When a MongoDB Server instance is started on a machine, it has to start listening on a port. By default, port number 27017 is used to mongod and mongos instances.

To begin using MongoDB, connect a mongo shell to the running instance. From a new terminal, issue the command:


Localhost Binding by Default

By default, MongoDB launches with bindIp set to, which binds to the localhost network interface. This means that the mongod can only accept connections from clients that are running on the same machine. Remote clients will not be able to connect to the mongod, and the mongod will not be able to initialize a replica set unless this value is set to a valid network interface.

For information on CRUD (Create,Read,Update,Delete) operations, see:
Insert Documents
Query Documents
Update Documents
Delete Documents

mongo command examples


show current db :


show all databases :

show dbs

> show dbs
admin             0.000GB
config            0.000GB
db_edureka        0.000GB
db_media          0.000GB
db_shopping_cart  0.000GB
local             0.000GB
userdata          0.000GB

show all collections in db :

use <dbname>
show collections

show all data in collection :


show first record in collection :


search records in collection :

db.movies.find( {“rate”:4.5} ).pretty()

search records in collection with selected fields : (projection)

db.movies.find( {“rate”:4.5}, {name:1, rate:1} ).pretty()

search records in collection with selected fields without internal id :

db.movies.find( {“rate”:4.5}, {_id:0, name:1, rate:1} ).pretty()

search records in collection without certain fields :

db.movies.find( {“rate”:4.5}, {_id:0, imageUrl:0} ).pretty()

show top two records in collection :


skip top two records in collection :


sort records in collection decending :


count records in collection :

db.<collectionName>.insert({“name”:”aakash”, “rollNo”:1})




create new db :

use <dbname>, 

Remove & Update

var item = db.collection.findOne({'condition':'some condition'})
db.collection.remove({_id: item._id});

db.collectionname.remove({"_id": ObjectId("5473293d43ecdre56352457f3a")})


  {“city”: “Helsinki”},
      “population”: 123456
  { upsert: true }