Disable built-in display with iogctl

[07151129]

Apple iogctl tool lets one simulate clamshell events. This makes it possible to disable the built-in display when there's an external display connected without closing the lid.

https://github.com/07151129/iogctl explains how to build and use the tool. Note that you need to set the boot-args from recovery OS if you have SIP enabled.

Note there's also https://github.com/Eun/DisableMonitor, but it attempts to do much more than iogctl, essentially replicating Apple logic for clamshell.

 

[profcutter]

Wow, this is a great tip, thank you!

 

[profcutter]

Ok, if I know nothing about Xcode and programming, how do I do this? I have a MacBook pro with a cracked screen, I want it to default to the external display. Thanks!

 

[07151129]

Here's a build compatible with 10.14.4 and newer. It has been tested with 10.14.6 but not with any newer OS version:

Release v0.1 · 07151129/iogctl

Contribute to 07151129/iogctl development by creating an account on GitHub.

github.com

Earlier OS versions need a different build of iogctl.

I usually do iogctl injectCS.enable; iogctl injectCS.close; iogctl injectCS.disable to fake clamshell close event. You may need to reconnect the external display afterwards. This could be automated with launchd.

Note that you have to update your boot arguments as described in the README (there are guides online that describe how to do that on a Mac).