On Linux (Ubuntu 11.10 on a ARM processor in my case) I was looking for a way to measure CPU temperature. I found out that acat /sys/class/thermal/thermal_zone0/tempdid the trick. Now I wonder: what is the /sys/class filesystem meant for?
/sys/class filesystem on Linux
linux;sysfs
/sys is an implimentation of the sysfs (system file system) various system internals can be read here, in a similar way /proc and the procfs shows process information. /sys/class shows information that relate to a class of device/attribute.You can read an overview in this linux.org article.