Adjust brightness from Terminal

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Mon, Sep 14 2009 at 7:30AM PDT • Contributed by: mat79

I've searched for a way to control the display brightness from the command line. I found several AppleScripts that open the System Preferences panel and set the slider, but I wanted a pure command line tool. Maybe someone else is looking for the same solution, so here is what I found:

This blog post discusses has a small commandline tool (written by Nicholas Riley) to set the brightness from Terminal. Just download the binary [4KB] and install it. You can then set the brightness by typing brightness 0 (to set it to minimum, use 1 for maximum, or any value between).

Note: The binary is Intel-Only (32-Bit), but the source code is available on the above linked page too, so you could easily compile a PowerPC or 64Bit Intel Binary on your own. I've tested it only with Snow Leopard and a self-compiled 64Bit binary, and it works fine

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Adjust brightness from Terminal
Authored by: billearl on Mon, Sep 14 2009 at 12:21PM PDT

For the uninitiated such as myself, PowerPC and 64Bit binaries, along with their installation location, would be useful. Thanks.

Adjust brightness from Terminal
Authored by: sabi on Mon, Sep 14 2009 at 1:07PM PDT

I'm the original author of the code listed in this hint. I originally wrote it for two reasons: first, to adjust brightness automatically by location on my iBook G4, which had no ambient light sensor, and second, so I could have my laptop turn on the backlight when a long operation finished, providing a quiet form of notification I could use while at a seminar.

http://sabi.net/nriley/software/brightness.zip is 4-way universal, 10.5+. I compiled it under 10.6 with:


gcc-4.0 -arch i386 -arch x86_64 -arch ppc -arch ppc64 -isysroot /Developer/SDKs/MacOSX10.5.sdk \
-mmacosx-version-min=10.5 -std=c99 -o brightness \
-framework Cocoa -framework DisplayServices \
-F/Developer/SDKs/MacOSX10.5.sdk/System/Library/PrivateFrameworks brightness.m

(note that if you compile it with the 10.6 SDK you'll get a deprecation warning; it's harmless for now.)

Adjust brightness from Terminal
Authored by: billearl on Tue, Sep 15 2009 at 8:01PM PDT

Thanks for this!

Just copied it to /usr/local/bin on my iBook G4 and it works great.

64-bit
Authored by: bankshot on Wed, Sep 16 2009 at 9:10AM PDT

I guarantee that 64-bit won't gain you anything at all in this case over 32-bit running on Intel. This is such a small and simple application that there's no benefit whatsoever to going beyond 32-bit, even on a system running all 64-bit stuff otherwise. Well, maybe a tiny psychological advantage for those who absolutely can't stand to have their system "polluted" by 32-bit stuff, but certainly no real-world advantage. ;)

That said, many thanks to the original author and to the hint submitter for calling attention to it! This program gives me a great idea to simulate an intermittent screen problem in my custom anti-theft script for my MacBook. Can't wait to try it out.

Adjust brightness from Terminal
Authored by: corienti on Mon, Sep 14 2009 at 2:32PM PDT

Absolutely brilliant! Thankyou!

Adjust brightness from Terminal
Authored by: luomat on Mon, Sep 14 2009 at 3:35PM PDT

There are instructions to compile this on the linked page.

The only problem I found is that it only dims the screen of the main display, not a second display hooked to a laptop.

Adjust brightness from Terminal
Authored by: BobHarris on Mon, Sep 14 2009 at 8:20PM PDT

The original brightness.c had a -d (display) option. I've been using this program for about 1/2 a year now and it works very nicely. The usage is something like:

usage: brightness [-m|-d display] [-v] 
   or: brightness -l [-v]

       -l   - Display current setting
       -d n - Use Display n (0, 1, 2, ...)
       -m   - Use the Main Display
       -v   - verbose

       0.0 to 1.0 - set the brightness from off to max
       brightness 1    # Full brightness
       brightness 0.5  # Half brightness
       brightness 0    # Display off

Adjust brightness from Terminal
Authored by: mario_grgic on Tue, Sep 15 2009 at 3:16PM PDT

This only works on my aluminum macbook, and iMac, it does not work on my mac pro with 30'' ACD.

Adjust brightness from Terminal
Authored by: sabi on Tue, Sep 15 2009 at 7:32PM PDT

Yeah, unfortunately Apple doesn't have a documented way of controlling brightness over USB. The documented method only works with built-in and ADC displays.

Use the version I linked above (http://sabi.net/nriley/software/brightness.zip) instead; it uses the same method as the Displays preference pane does.

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