use admin
db.createUser(
  {
    user: "adminUserName",
    pwd: "userPassword",
    roles:
    [
      {
        roles: "userAdminAnyDatabase",
        db: "admin"
      }
    ]
  }
)

mongo --host xxx -u adminUserName -p userPassword --authenticationDatabase admin

db.runCommand(
  {
    usersInfo:"userName",
    showPrivileges:true
  }
)

use db01
db.createUser(
  {
    user:"oneUser",
    pwd:"12345",
    roles:[
      {role:"read",db:"db01"},
      {role:"read",db:"db02"},
      {role:"read",db:"db03"}
    ]
  }
)

use admin
db.createUser(
  {
    user:"superuser",
    pwd:"pwd",
    roles:["root"]
  }
)

use admin
db.changeUserPassword("username", "xxx")

db.runCommand({usersInfo:"userName"})

db.runCommand(
  {
    updateUser:"username",
    pwd:"xxx",
    customData:{title:"xxx"}
  }
)