#MongoDB 3.2.x Logging
The main log file is the mongod.log. You can specify the log file location when you are starting the mongod process but if you have installed on Ubuntu from a package then you log file will normally be located in /var/log/mongodb/mongod.log.
You can tail the log file using:
tail -f /var/log/mongodb/mongod.log
From the Mongo shell you can also view the log file using:
show logs