Install bwbar by entering the following commands in the terminal:
sudo apt update sudo apt install bwbar
generates text and graphical readout of current bandwidth use
This program will output a PNG and a text file that can be used in scripts or be included in web pages to show current bandwidth usage. The amount of total bandwidth can be customized. The PNG output appears as a bar graph showing maximum possible usage with the current inbound or outbound usage shown as a differently colored bar.