This post provides instructions on how to monitor CPU emperatures from command line on Ubuntu.
Step 1: Install lm-sensors using the following command in your terminal
$ sudo apt-get install lm-sensors
Step 2: type the following command in terminal
$ sudo sensors-detect
You will be asked a few questions. Answer Yes for all of them.
Step 3: type sensors in your terminal to get your CPU temperature.
Step 4: You can run the following command to see temperature values updating each second
$ watch sensors
$ watch -n 10 sensors # this will update the temperature values every 10 seconds. You got the idea -- you can change the number 10 to any seconds you would like to see the updated temperature values.
Step 5: use Ctrl + C to terminate.