mongosh (the MongoDB Shell) is the interactive command-line interface for MongoDB — a JavaScript environment for connecting, running queries, and administering databases. It's used for development, debugging, and administration, with JavaScript syntax for operations.
mongosh
mongosh
show dbs
use mydb
show collections
db
mongosh is a full JavaScript REPL — you can use JS variables, loops, and functions alongside database commands.
// CRUD operations (the db object refers to the current database)
db.users.insertOne({ name: "Ann" });
db.users.find({ age: { $gt: 25 } });
db.users.find().pretty(); // pretty-print results (readable)
db.users.updateOne({ name: "Ann" }, { $set: { age: 31 } });
db.users.countDocuments({ active: true });
You run the same CRUD and aggregation operations as application code, using the db.collection.method() syntax.
db.users.stats(); // collection statistics
db.users.getIndexes(); // list indexes on a collection
db.users.createIndex({ email: 1 }); // create an index
db.users.explain().find({ ... }); // see the query plan (performance)
db.stats(); // database statistics
db.serverStatus(); // server info
mongosh handles administration too — creating indexes, viewing stats, analyzing query plans (explain for performance), and managing the database.
// use JavaScript for scripting/bulk operations
for (let i = 0; i < 100; i++) {
db.test.insertOne({ num: i });
}
const count = db.users.countDocuments();
print(`Total users: ${count}`);
mongosh is the essential, everyday tool for working directly with MongoDB — developers and administrators use it constantly to connect, query, inspect, and administer databases, so knowing its essentials is practical, fundamental knowledge for MongoDB work.
While GUI tools (MongoDB Compass) exist, mongosh is the universal, always-available command-line interface, and a distinctive advantage is that it's a full JavaScript REPL — you can use JavaScript variables, loops, and functions alongside database operations, enabling scripting, bulk operations, and complex logic directly in the shell.
Knowing how to connect, navigate (show dbs, use, show collections), run CRUD and aggregation operations (db.collection.method()), and especially perform inspection and administration (creating indexes with createIndex, viewing indexes and stats, and using explain to analyze query plans for performance) is everyday practical knowledge for any MongoDB developer or administrator.
The explain capability in particular is valuable for diagnosing query performance.
Since mongosh is the standard, ubiquitous interface to MongoDB — used for development, debugging, administration, scripting, and exploration — understanding its essential commands and that it's a JavaScript environment is valuable, frequently-applied knowledge that makes working with MongoDB efficient, a basic competency expected of anyone working with the database directly, analogous to knowing psql for PostgreSQL.