Use the current desktop environment’s notification system to create a notification. More information: https://manned.org/notify-send.
notify-send "{{Test}}" "{{This is a test}}"
notify-send {{[-i|--icon]}} {{icon.png}} "{{Test}}" "{{This is a test}}"
notify-send {{[-t|--expire-time]}} 5000 "{{Test}}" "{{This is a test}}"
notify-send {{[-u|--urgency]}} {{low|normal|critical}} "{{Test}}" "{{This is a test}}"
notify-send "{{Test}}" {{[-i|--icon]}} {{google-chrome}} {{[-a|--app-name]}} "{{Google Chrome}}"