title: How to change the brightness of screen on ubuntu 16.04
body: <p>I've move my system (ubuntu 16.04) from a computer with intel cpu to a computer with amd cpu. I've found that there is no single file or directory under <code>/sys/class/backlight/</code>, so <code>echo 30 &gt; /sys/class/backlight/intel_backlight/brightness</code> is not working(but this command worked well in a computer with intel cpu). When I try to create a folder under <code>/sys/class/backlight/</code> with root permission, I got an error <code>Operation not permitted</code>. I've also tried <code>xbacklight</code>, it does not work as well. How can I change the brightness of screen in such situation. Thanks.</p>