Real Temp is not available for Linux but there are a few alternatives that runs on Linux with similar functionality. The best Linux alternative is Lm-Sensors, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Real Temp and three of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to Real Temp are GtkStressTesting (Free, Open Source) and Linpack Xtreme (Free).
Linpack is a benchmark and the most aggressive stress testing software available today. Best used to test stability of overclocked PCs. Linpack tends to crash unstable PCs in a shorter period of time compared to other stress testing applications.