Error using SpeedFan - how can I control fan speed?

SpeedFan is a Windows-only program. It will not work in Linux. There is an application in the default Ubuntu repositories that has similar functionality to SpeedFan called Psensor. Psensor is an application for monitoring hardware sensors, including temperatures and fan speeds.

Install Psensor. Also install lm-sensors to detect your computer's hardware sensors, and detect your computer's hardware sensors by running these commands:

sudo apt install psensor lm-sensors
sudo sensors-detect

Then you will get asked a lot of questions about what hardware you want the program to detect. It is generally safe and recommended to accept the default answers to all questions, unless you know what you're doing.

In Ubuntu 16.04 and later Psensor detects your computer's hardware sensors automatically without running sudo sensors-detect

Psensor displays itself on the desktop as a little thermometer icon in the notification area in the upper right corner of the desktop. You can right-click the thermometer icon at any time to display the hardware temperatures.