Random idea number eleventeen

On a tech forum I visit often, we were discussing the various ways to
power down a computer when power goes out (apart from the boring way
of making your UPS automatically doing it for you). Now that I think
about it, I’m really obsessed with shutting computers down. I had an
idea long ago which was quite stupid but I’m gonna note it down anyway
so that I can laugh about it later. Also, I want to ensure that
Shampoo doesn’t patent it.

What if I could shut down my computer by making it listen to the
annoying beeps that UPSes usually make? All the cheap ones don’t have
an option to turn that off, so I could probably use it as signal to
power down. Considering that linux has finally implemented some sort
of “sound framework” that doesn’t (theoretically at least) lock sound
devices when a process accesses it, it should be quite trivial to
create a lightweight daemon that samples from the system microphone
and checks for the annoying beep waveform. If it matches, kill the
system.

Two or three questions come to mind. The “Why do this?” can be
answered with “whatevs, becoz i can”. The other more pertinent
questions are:

• How difficult would this be to pull off?
• Wouldn’t it be annoying to have a microphone connected to your
  system all the time?
• Would it not be resource intensive to continuously poll the mic?
• Are there any libraries which would make it easy for me to pull
  this off without resorting to hacks?
• And finally, if i ran around with a beeping thingamajig, would it
  not be possible to start a shutdown? How can one protect against this?

I hope to try it out this weekend, let’s see if it can be done.