Notes for package maintainers (and perhaps suitable for finding solutions to 
your problem with no hddtemp being displayed):

This version now has optional compile-time support for libsensors3, hddtemp and
ACPI stuff. Thus, when creating packages, you have the choice to deliver a 
package with all features, which then strongly depends on all of the compiled-in 
features and libraries.

hddtemp is no longer searched at run-time, it is only enabled at compile-time.

If you know of any further OS-specific interface or system library that might be worth including, please tell me. 

For hddtemp to work for users in the plugin, it must be setuid root or a hddtemp daemon must be running. if none of this is done, it cant display the hddtemp. A possible workaround consists of adding a wrapper script as option to --with-pathhddtemp, that will call sudo on hddtmep.

