Interested in how much bandwidth you are using? vnStat is a simple command line utility to track network traffic on a Linux computer. vnStat is easy to set up and use on Ubuntu, and works well on both server and desktop systems.
Run these three commands to install vnStat and set up permissions so every user can run it:
sudo apt-get install vnstat
sudo chmod o+x /usr/bin/vnstat
sudo chmod o+wx /var/lib/vnstat/