How to copy a Database from a MongoDB instance to another?

While recently i was working in an application i had to copy the database from a mongoDB  hosted in an mlab instance to my local. I will share an easy step in MongoDB Shell which support to copy database from remote instance to current one with a single command.

DEMO with steps :

I made  two instances of MongoDB from following commands.

 //Instance 1  
 mongod --port 9998 --dbpath /data/db1  
 //Instance 2  
 mongod --port 9999 --dbpath /data/db2  

In instance 1 there is a database called "dsampledb1".

and i started the instance with the following command,

 mongo localhost:9998  

I create a database with one collection with the following command,

 use dsampledb1  
 db.users.save({id:1, name:"sample name"})  

Then I log in to next MongoDB instance using MongoDB Shell.

 mongo localhost:9999  

Now to copy the database from the instance 1 to instance 2 , we can simply use the following command,

 db.copyDatabase("dsampledb1","dsampledb2","localhost:9999")  

Syntax is as follows,

 db.copyDatabase(sourcedb, destinationdb, fromhost, username, password)