xbacklight stopped working just now after an 'apt updgrade'. Ubuntu 16.04.3, Dell XPS-13. Writing directly to /sys/class/backlight/intel_backlight/brightness still works.
xbacklight stopped working just now after an 'apt updgrade'. Ubuntu 16.04.3, Dell XPS-13. backlight/ intel_backlight /brightness still works.
Writing directly to /sys/class/