MongoDB Shell — MongoDB

MongoDB Shell (mongosh)

mongosh is the official MongoDB Shell — a Node.js REPL for interacting with MongoDB. It replaced the legacy mongo shell in MongoDB 5.0+ and supports modern JavaScript, autocompletion, and a configurable prompt.

Connecting to MongoDB

Connection examples

Bash

# Connect to local MongoDB on the default port (27017)
mongosh

# Connect to a specific port
mongosh --port 27018

# Connect with authentication
mongosh --username admin --password secret --authenticationDatabase admin

# Connect to MongoDB Atlas
mongosh "mongodb+srv://cluster0.xxxxx.mongodb.net/myDatabase"   --username myUser

Essential Shell Commands

Command	Description	Example
show dbs	List all databases	show dbs
use <db>	Switch to (or create) a database	use myapp
show collections	List collections in current db	show collections
db.stats()	Show database statistics	db.stats()
db.version()	Show MongoDB server version	db.version()
db.hello()	Show replica set info and connection details	db.hello()
exit / .exit / quit()	Exit the shell	exit

Database Operations

Database operations

// List all databases
show dbs

// Switch to a database (created on first write)
use mydb

// Get the current database name
db.getName()

// Drop the current database
db.dropDatabase()

Collection Operations

Collection operations

// Explicitly create a collection with options
db.createCollection("users", { capped: false })

// List all collection names
db.getCollectionNames()

// Get collection statistics
db.users.stats()

// Drop a collection
db.users.drop()

Running Your First Queries

Basic CRUD in mongosh

// Insert a single document
db.users.insertOne({ name: "Alice", age: 30, city: "Berlin" })

// Insert multiple documents
db.users.insertMany([
  { name: "Bob",   age: 25, city: "Paris" },
  { name: "Carol", age: 35, city: "Tokyo" },
])

// Find all documents
db.users.find()

// Find with a filter
db.users.find({ city: "Berlin" })

// Update a document
db.users.updateOne(
  { name: "Alice" },
  { $set: { age: 31 } }
)

// Delete a document
db.users.deleteOne({ name: "Bob" })

Using Variables and JavaScript

JavaScript in mongosh

// Assign a document to a variable
var user = { name: "Dave", role: "admin", active: true }
db.users.insertOne(user)

// Insert multiple documents with a loop
for (let i = 1; i <= 5; i++) {
  db.products.insertOne({ sku: `PROD-${i}`, price: i * 10 })
}

// Define and call a helper function
function countActive() {
  return db.users.countDocuments({ active: true })
}
countActive()

mongosh Configuration

mongosh loads ~/.mongoshrc.js at startup. You can use it to set a custom prompt, define helper functions, or connect to a database automatically.

~/.mongoshrc.js

// Show current database in the prompt
prompt = function () {
  return db.getName() + "> "
}

// Shorthand helper
globalThis.lf = (coll) => db[coll].find().toArray()

Running Script Files

Bash

# Run a JavaScript file against the local server
mongosh script.js

# Run a one-liner without opening an interactive session
mongosh --eval "db.users.countDocuments()"

# Run a script against a remote server
mongosh "mongodb+srv://cluster0.xxxxx.mongodb.net/mydb" seed.js

Useful Helpers

.pretty() is no longer needed — mongosh formats output automatically
cursor.toArray() — converts a cursor to a plain JavaScript array
cursor.forEach(fn) — iterates over every document in a cursor
db.collection.explain() — returns the query plan instead of results
db.collection.explain("executionStats") — includes execution statistics

Tip

Use Tab for autocompletion in mongosh — it knows MongoDB method names and your collection names. Press Tab twice to see all available options.

Note

mongosh supports modern JavaScript (ES2020+) including async/await, optional chaining, and nullish coalescing — the legacy mongo shell did not.