xbacklight worked perfectly in Kubuntu 14.04 but now in Kubuntu 16.04, even when it it installed, I only get this message:

No outputs have backlight property

In my system there is a /sys/class/backlight folder already, so please note that this is not a duplicate of the completely different question in xbacklight: No outputs have backlight property - No /sys/class/backlight folder where the OP very clearly states in the title I do have a /sys/class/backlight folder, so this is not the same case, please read the title of that question where it says explicitly "no /sys/class/backlight folder"

  • it's a bug in KDE. You can write directly to the file to change brightnes, but keyboard controls and brightness slider have no effect – ravery Jan 27 '18 at 7:12
  • @ravery Nope. I can control the screen brightness with the function keys perfectly. But not from shell scrips or the konsole using xbacklight. – Mephisto Jan 27 '18 at 7:16
  • Hmm, different but possible related. In my case KDE was looking for video_bl0 (or something like that) when I have radeon_bl0. Perhaps yo have a similar issue. My backlight works perfectly with Mate desktop. – ravery Jan 27 '18 at 7:25

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