Example: ping google.com
until it becomes reachable (for testing when internet connection is back), then notify with an audio message
until ping -W1 -c1 google.com; do sleep 5; done && say connected
It's also possible to use different notification means (e.g., notify-send on Ubuntu, growl on Mac, pushover, etc.).
Notes on ping:
ping -W1 -c1 google.com
means ping just once (-c1
) and wait for reply for 1 second (-W1
). It returns 0 if host is reachable, error otherwise.