Monday, 3 May 2010

Enabling Hardware Sensors in Linux

1. Installing the sensor libraries
First thing’s first – you need to install the libraries that allow Linux to read your sensors. To do this, install the lm-sensors library, by running the command:

sudo apt-get install lm-sensors
This will install the libraries for your motherboard’s sensors. For your hard-disk sensors, you’ll want to install hddtemp:

sudo apt-get install hddtemp
In Ubuntu, the install will ask you several questions. First it will ask if it should run SUID root, select “yes.” It will then ask you for an interval for logging the temperature to a file; since we are going to have an applet display our system temperatures for us, this isn’t necessary, so most users will be fine leaving the default of ‘0′ and pressing enter; if you wish to log this data, however, I’d recommend a value between 2 and 10 seconds. Next, it will ask if it should run as a deamon; select yes, and leave the default values for hostname and port. Finally, it will ask if you wish for it to run on startup – select “yes.”
2. Running sensors-detect
Now that your sensor libraries are installed, you need to detect your sensors! Run the command:

sudo sensors-detect
Which will probe your system for sensors. Answer “YES” to all questions! Don’t just hit enter, type “YES”, because at the end there will be a question for which the default answer is “no”, and we’ll want to answer in the affirmative.
The sensors-detect program will scan yur system, and then give you a summary, stating which sensors it has found. It will then say: I will now generate the commands needed to load the required modules. After you hit ENTER to continue, it will ask, Do you want to add these lines to /etc/modules automatically? (yes/NO) This is the question we want to make sure we answer YES to.
3. Loading the modules
Since we answered YES to the previous question, our sensor modules will be loaded by default the next time we start up. But since we don’t want to have to reboot, we’re going to use the information we got from the sensors-detect script to load the modules ourselves, this time only. Right above the last question will appear a list of modules that you should load, in the form of:
#----cut here----
# Chip drivers
#----cut here----
You may have more, or different, items listed – that’s fine! What we want to do now, to load these modules, is use the modprobe command, as follows:

sudo modprobe [module name]
So, in my case, I would type:

sudo modprobe smsc47m1
If all goes well, you should be returned to the command-line, without any output.
4. Monitoring the sensors!
Wow, that was a lot of work! Now, let’s see the rewards. On the command line, you can simply run the

command; this will output the information from your motherboard’s sensors.
However, we’d rather have a graphical interface for checking up on our hardware, so let’s install an applet for our Gnome desktop to keep an eye on our system’s temperature. Run the command:

sudo apt-get install sensors-applet
to install the applet. Now, add the applet by right-clicking on your desktop panel, selecting “Add to Panel,” and you will now see a “Hardware Sensors Monitor” applet in the System & Hardware section. Click and drag this to your panel to add it.
The applet will now say that you haven’t enabled any sensors; right click on the applet and open its preferences. The first screen is for general settings:
General Sensor Settings Image
The options here are self-explanatory; for update interval, choose a value between two and ten seconds. The second screen is where you can enable your sensors to be displayed in the applet:
Sensor Selection Image
Here we have my hard drive, /dev/sda, enabled. Simply check off the sensors you want to enable, and they will appear in your panel!
Hopefully by now, you’ll see icons in your panel, with thermometers and temperature readouts, keeping you apprised of the status of your system’s hardware. You’ll notice that when doing intensive operations, various parts of your system will increase in temperature; this is normal, and this applet will help you keep an eye on things so nothing overheats.

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