MongoDB is a free and open source document  based DBMS . Use the following command for MongoDB installation:

1) Execute the following command to import the public GPG Key. 

 sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10

2) Following command will create a new file "mongodb.list" in /etc/apt/sources.list.d/  folder and will write the MongoDB repository details.
    

 echo 'deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen' | sudo tee /etc/apt/sources.list.d/mongodb.list

3) Update the Packages .
  

sudo apt-get update

4) Now finally install the MongoDB.
  

sudo apt-get install mongodb-10gen=2.2.3    

5) Now MongoDB is installed to your system. To verify the MongoDB installation execute the following command in shell and it will display the following output.

 mongo
 Output:
    MongoDB shell version: 2.2.3
    connecting to: test
    Welcome to the MongoDB shell.

    Create and display the databases commands:

    1) Following command will create a database named nirmala and will switch to that database.   

use nirmala

    2) Check the current database.    

   db    

    3) Following command will display all the databases list.    

show dbs