T 43 fan control daemon

As I mentioned earlier, one of the more annoying properties of the Thinkpad T43 is that its fan is running almost constantly, even when the device is basically cold.

This daemon controls the fan: When a certain temperature is exceeded, the fan is turned on. When fan speed drops below a certain threshold, it’s turned off. The daemon tries to be safe by turning on the fan when it is killed or otherwise encounters an error. If that doesn’t happen, there’s an emergency broadcast through syslog.

WARNING: Turning off the fan might lead to overheating of your machine. Use at your own risk. This daemon may have bugs that could lead to this situation.

Update, April 2013: Since this code is apparently still looked at, I’ve put it on github. Note that this is completely unmaintained, eight year old code.