Skaperen wrotean app that can ring your bell and can scan the log file for the right text, or ping a known host via the tunnel, could solve your need.
This may very well be true, and I appreciate the advice since nobody has to offer any advice.
However, unfortunately, I have two responses to that which negate it as a practical matter:
1. This thread is expressly for the openvpn app to add the feature, not for a second unrelated app to add the feature. 🙂
2. Besides, nobody knows how (yet) to make a secondary app ring the bell either.
For details on the second issue above, see the related thread exactly asking HOW to ring a bell (any way possible) when OpenVPN connects:
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How can I get OpenVPN Daemon to ring a bell upon "Initialization sequence completed
After two months, we still have been unable to even get a secondary app to ring a bell upon OpenVPN completion.