vcgencmd is a command line utility that can get various pieces of information from the VideoCore GPU on the Raspberry Pi. Much of the information available is only of use to Raspberry Pi engineers, but there are a number of very useful options available to end users that will be described here.
In my trial on Ubuntu Desktop for Raspberry Pi, vcgencmd is installed by default. But fail with error of "VCHI initialization failed".
To fix it, add the video group to your user:
$ sudo usermod -aG video <username>
After log-out and log-in.
