I ran an IT consultancy for roughly 8 years. During that time, I developed a number of little apps/services/scripts that did tasks like this, one being the so-called HyperBeacon. I had versions of the "pinger" that ran in C# (Windows service, console (.NET and Mono)), Python (Windows service, console (cross-platform) and Unix daemon (fork and detach, daemontools/svscan)), native Win32 API C (Windows service and console)... as well as, as you've requested here, bash scripting (the transport was UDP, so this used the /dev/udp pseudo-devices bash provides; these aren't actual filesystem nodes, but they're detailed in the bash Texinfo manual).
I've written more than a few non-trivial scripts in bash (as well as other shells, but bash provides some really compelling features) and am quite familiar with its various facilities for concurrency, string manipulation/parsing, pipes, process control, variable manipulation (including associative arrays), and internal arithmetic. I think what I love about bash scripting is that it requires a very different approach to things than most any other language I've used, but is still quite capable.
Anyway, this sounds like an interesting project, and I'm new here and keen to build my reputation and make some more cash to take more exams and such. If you'd like examples of some code I've written, I'll happily send them over- just let me know what sort of thing you're looking for. (Still building out my profile & haven't gotten to the portfolio.)