This command only works on laptop/netbook computers.
It allows you to set the brightness of the laptop screen.
The [level] parameter is brightness value
between 0 and 100. 0 = very dark, 100 = very bright.
{mode} is optional parameter that
may conatin the following values:
1 = Change the brightness under AC power.
2 = Change the brightness under DC power.
3 = Change the brightness for both AC power amd DC power (The default).
Examples:
setbrightness 50
setbrightness 40 1
setbrightness 60 2
