2

I would like to be able to interrupt watch if execution of command was successful. In effect, I'm looking for a reverse behaviour than that offered via --errexit. As per man:

-e, --errexit Freeze updates on command error, and exit after a key press.

Example

The command:

ping -c 3 www.google.com

Fails due to the patchy connection*. I can re-run in the following manner to see when the connection is back:

watch -n 1 'ping -c 3 www.google.com'

I would like to stop watch if ping executes with no error.


* I'm not looking to find a better of way of verifying connectivity. The ping examples comes from using a mobile phone connection when on the train with mobile phone loosing signal every so often.

2

Since you would start receiving pings once your network connection has been restored, start the watch after your connection has dropped and tell it to exit once the output changes:

watch -g -n 1 ping -c 3 www.google.com

As soon as you start receiving pongs, watch will exit.

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