SOLVED, in a indirect way. Not doing Fn+F5 or Fn+F6, but F5 or F6 only...
To do that, for F5, I created a script as:
#!/bin/bash
currentBrightness=`cat /sys/class/backlight/acpi_video0/actual_brightness`;
myBrightness=$currentBrightness - 1;
if [ $myBrightness < 1 ]; then
myBrightness=1;
else
xdotool key XF86MonBrightnessDown;
fi`.
With execution permission given to the script, with Ubuntu Tweak (Administration > Shortcuts) I binded the script to F5 key.
For F6 key, the script is:
#!/bin/bash
currentBrightness=`cat /sys/class/backlight/acpi_video0/actual_brightness`;
myBrightness=$currentBrightness + 1;
if [ $myBrightness > 10 ]; then
myBrightness=10;
else
xdotool key XF86MonBrightnessUp;
fi`
Another simple alternative is install Brightness Indicator. Instructions in: http://www.noobslab.com/2012/11/indicators-collection-for-ubuntu.html
/etc/default/grub
, in lineGRUB_CMDLINE_LINUX_DEFAULT
andGRUB_CMDLINE_LINUX
?