> So what happens if I interrupt the script with ^C?  Do I end up with
> my terminal in the "stty nokerninfo" state?

trap cleanup EXIT

Hundreds of programs change the tty configuration and restore it upon
interrupt.  Most are written in C.  In sh, it is possible to write programs
which capture exit signalling jus as well as C code.

I don't think this is really a drama.  fw_update is run rarely.  When it
doesn't work well, we want to know why.  I've found previous bugs in here
using sh -x, and that is tiring.