Here’s how I prevented my iBook G4 notebook from going to sleep when the lid is closed. This worked with Mac OS X 10.3.9 (Panther). YMMV. If you’re running a OS X 10.4 (Tiger) or newer, you might want to check out InsomniaX instead. InsomniaX should work with Mac OS X 10.4 and later.

  1. Download and decompress Insomnia.kext.tbz. I wasn’t able to retrieve a copy of from the Insomnia project’s home page, but I did grab a working copy off of the Internet Archive, which I mirrored here. I also mirrored a copy of the source code in the Insomnia.src.tbz file.
  2. Open a command prompt, switch to the directory that you decompressed Insomnia.kext.tbz to, and execute the following commands:
    1. sudo chown root:wheel Insomnia.kext # set the module to be owned by root
    2. mv Insomnia.kext /System/Library/Extensions # move the module to the kernel extensions directory
    3. cd /System/Library/Extensions # change to the kernel extensions directory
    4. sudo kextload Insomnia.kext # load the module
  3. Test the module by closing your notebook’s lid. If your Mac doesn’t go to sleep, you’re in business.

You can unload the Insomnia.kext module at any time by executing the following commands:

  1. cd /System/Library/Extensions # change to the kernel extensions directory
  2. sudo kextunload Insomnia.kext # unload the module