mongo Shell Quick Reference

mongo Shell Command History

You can retrieve previous commands issued in the mongo shellwith the up and down arrow keys. Command history is stored in~/.dbshell file. See .dbshell for moreinformation.

Command Line Options

The mongo shell can be started with numerous options. Seemongo shell page for details on allavailable options.

The following table displays some common options for mongo:

Command Helpers

The mongo shell provides various help. The following tabledisplays some common help methods and commands:

Basic Shell JavaScript Operations

The mongo shell provides aJavaScript API for database operations.

In the mongo shell, db is the variable that referencesthe current database. The variable is automatically set to the defaultdatabase test or is set when you use the use <db> to switchcurrent database.

The following table displays some common JavaScript operations:

coll = db.myCollection;

coll.find();

For more information on performing operations in the shell, see:

• MongoDB CRUD Operations
• mongo Shell Methods

Keyboard Shortcuts

The mongo shell provides most keyboard shortcuts similar tothose found in the bash shell or in Emacs. For some functionsmongo provides multiple key bindings, to accommodateseveral familiar paradigms.

The following table enumerates the keystrokes supported by themongo shell:

Queries

In the mongo shell, perform read operations using thefind() and findOne()methods.

The find() method returns a cursor objectwhich the mongo shell iterates to print documents onscreen. By default, mongo prints the first 20. Themongo shell will prompt the user to “Type it” to continueiterating the next 20 results.

The following table provides some common read operations in themongo shell:

coll = db.users;coll.find( { name: "Joe" } );

coll = db.users;coll.find( { }, { name: true } );

coll = db.users;coll.find().sort( { name: 1 } );

coll = db.users;coll.findOne( { name: "Joe" } );

See Query Documents documentation for more information andexamples. See Query and Projection Operators to specify other queryoperators.

Error Checking Methods

Changed in version 2.6.

The mongo shell write methods now integrates theWrite Concern directly into the method execution ratherthan with a separate db.getLastError() method. As such, thewrite methods now return a WriteResult() object thatcontains the results of the operation, including any write errors andwrite concern errors.

Previous versions used db.getLastError() anddb.getLastErrorObj() methods to return error information.

Administrative Command Helpers

The following table lists some common methods to support databaseadministration:

See also administrative database methods for a full list of methods.

Opening Additional Connections

You can create new connections within the mongo shell.

The following table displays the methods to create the connections:

db = connect("<host><:port>/<dbname>")

conn = new Mongo()db = conn.getDB("dbname")

See also Opening New Connections for more information on theopening new connections from the mongo shell.

Miscellaneous

The following table displays some miscellaneous methods:

Additional Resources

Consider the following reference material that addresses themongo shell and its interface:

• mongo
• mongo Shell Methods
• Database Commands
• Aggregation Reference
• Getting Started Guide

Additionally, the MongoDB source code repository includes a jstestsdirectorywhich contains numerous mongo shell scripts.