You are using quite an old version of cgminer (3.1.1) here. As a heads up for any newbies reading this, this is the latest version that supports the -S parameter. More recent versions expect to communicate directly with the the USB driver, so the setup procedure is quite different. Perhaps you would like to update your tutorial with this information?
That's a good point. I did compile the latest version (3.3.1), but couldn't get it to run. But if I can get it to run, I'll post the instructions here.
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(a stand-alone RPi distribution based on ArchLinux) is well thought of too.