And now to give you a practical example what I personally do with lua(4)
right now: In the past I wrote several tty line disciplines to decode
various serial formats. Now I have a need for that again. Doing this
in C is of course possible, but I want something more dynamic. So I
wrote a tty line discipline that uses Lua to do all the decoding. That
works like a charm: Load the script, test, change the script and
reload. Really practical. I will release this code once I sorted out a
few remaining details. And in the course of this work, I also found
deficencies in slattach(8).
In previous work I used Lua to create a software gpio device, a modified
version of gpiosim(4) that uses a Lua script to "mimick" a real device.
Also handy.