Changing Laptop Screen Brightness from the command-line

My new Dell Studio 15's laptop screen is great. It is bright, and by bright I mean that on full brightness I can use it outside on a sunny day with my sunglasses on and still read the screen comfortably. This brightness is great except for cases when I don't want it so bright, like when I'm working in a darker room. One night I discovered that the lower third of my vision had a dark blind spot after doing some work while watching a movie. That can't be good.

Problem is, I don't always remember to adjust the brightness, and from what I can tell, it always boots into Ubuntu af full brightness, so I dug around for a way to change the brightness automatically. Thanks to google I found a post over on LinuxScrew that talks about changing the brightness for a dell inspiron 1501. Turns out the Studio 15 has a similar method using /proc. Cat'ing the file shows me the acceptable brightness levels:

# cat /proc/acpi/video/M86/LCD/brightness 
levels:  6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 100
current: 100

Echo'ing something to the file (as root) sets the value:

# echo -n 18 > /proc/acpi/video/M86/LCD/brightness 

There's lots of places to go with this, but for now I'm going to pop it into rc.local and run with it.

No more blind spots, excellent.