Create a MongoDB user from commandline

Question

I have set up a MongoDB database with an admin user that has only administrative rights, not read or write access to databases.

What I now would want to do

Answer 1

Above in my case didn't worked

use dummyDb

db.createUser({user: "admin",pwd: "secrectP@wd",roles: [ { role: "readWrite", db: "reporting" } ],mechanisms: [ "SCRAM-SHA-256" ]   }