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I usually plug my MBP 15" late 2011 (El Capitan 10.11.2) with an external monitor, and I only use that. Also I need to use the trackpad.

So I need to turn off the built-in monitor with the clamshell open. Possibly using a terminal command. How can do it?

I already tried this solution (for Yosemite) but doesn't work on El capitan: https://apple.stackexchange.com/a/154600/90762

And I already tried DisableMonitor app but it reduces the brightness of the monitor to 0 and it remains on! So probably it consumes more. Is there a way to completely turn off?

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  • I changed title and description to better focus my problem, that is turn off monitor with clamshell open and possibly using a terminal command on El Capitan.
    – Fred K
    Commented Dec 16, 2015 at 16:20
  • What about set brightness to zero? Or does that also affect the external display?
    – pwn'cat
    Commented Dec 18, 2015 at 10:16
  • I'd hazard a guess that all terminal and app based solutions won't work in El Capitan because of SIP. Although it can be disabled, this might be the easiest solution.
    – Joonas
    Commented Dec 18, 2015 at 10:50
  • @Joonas: is it reccomendable to disable it or it's like an hack? Anyway, if I use the notable DisableMonitor app (as everyone seem to use with great satisfaction) it simply decreases the luminosity to 0 but is it the same as disable the monitor, in terms of consumption?
    – Fred K
    Commented Dec 21, 2015 at 18:01
  • @FredK, to be honest, I couldn't tell you if or how any of those solutions worked on prior versions, since I haven't tried any of them. This makes me think that DisableMonitor had to settle for brightess reduction in El Capitan (for now?). The terminal solutions seem pretty legit too, this one for example. I'd guess they don't work because of SIP.
    – Joonas
    Commented Dec 22, 2015 at 8:47

4 Answers 4

Reset to default
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You can also just mirror the display of the MacBook screen to the external one and then turn off the brightness of the Macbook screen (so it turns fully black). Then you can keep the lid open of your MacBook AND use the TrackPad.

System Preferences > Displays > Arrangement > Select "Mirror Displays".

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  • Note that this only turns off the backlight, but the display is still on.
    – Michael Wu
    Commented Jan 6, 2021 at 16:51
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Given how none of the old methods seemed to work in El Capitan, the magnet method sounded pretty interesting to me, so I decided to try it.

I got the smallest and weakest hobby/craft magnet I had, and ran it through the top left corner of the Macbook Air, as some of those other answers said that's the location. I suspect the location may differ between Macbook models.

In my MacBook Air (13-inch, Mid 2012), the location seemed to be on the left side, slightly above the Tab key.

I used Pritt multi tack to keep the magnet in place, but you could use double sided tape, for example. If I wanted to be really careful with the magnet, I could've put a spacer between the Macbook surface and the magnet about the height of the magnet itself, and it still would've worked.

There's one kinda big downside to this.

  • If you stop using the Macbook touchpad or keyboard for something like 3 seconds, they stop working. You then need to remove the magnet to re-enable them. This is kind of a deal-breaker, if you don't want to use external mouse and keyboard.

If you are ok with using an external keyboard and mouse, this seems like the best method to me.

enter image description here

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  • The magnet method is an old classic! I always avoid it because I'm afraid to put any magnetic object close to any electronic device. I knew that magnet could create issues to electronic devices (such as hard disk). Is it right?
    – Fred K
    Commented Jan 1, 2016 at 13:26
  • @FredK When you think about it, macbook's have plenty of magnets already. This might depend on the model, but there's: 2 magnets on top of the screen, on both sides of the camera. Those keep the lid firmly closed. There's the charging port magnet and then here's the magnet that closes the screen. What they use there is a reed switch (to my knowledge). They are already using a magnet to activate it so I personally don't feel too much anxiety sticking a magnet there myself. As long as the magnet is small and not very strong, my mind is at ease.
    – Joonas
    Commented Jan 1, 2016 at 17:23
  • That said, I wouldn't run a horseshoe magnet all around the laptop :) Here's a picture where I placed an average metal wire on the lid. This is the magnet that closes the screen, when you close the lid. You can use that point to determine how strong of a magnet you should use in its place (not very stong at all). If using a magnet to do this still seems scary, reading this should ease your mind.
    – Joonas
    Commented Jan 1, 2016 at 17:42
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Close the lid of your MacBook.

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  • 1
    It goes to standby then turn off also the external monitor
    – Fred K
    Commented Dec 16, 2015 at 14:19
  • Does it wake back up if you press a key on your keyboard?
    – orkoden
    Commented Dec 16, 2015 at 14:27
  • This is a very bad suggestion, due to how hot the Macbook gets when the display is closed, blocking the vents just north of the keyboard.
    – Martin
    Commented Dec 20, 2015 at 16:37
  • I read somewhere (I can't find the link) that MBP dissipate on the bottom, so there are no problems to keep the lid close. I could be right, but I'm with @Martin
    – Fred K
    Commented Dec 21, 2015 at 17:56
-1

SwitchResX works for me: you can easily disable displays in its GUI.

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  • Welcome to Ask Different. We are looking for more than a single line answer. It's helpful if you provide links and/or references to solutions you have found and why you think your answer is right.
    – Allan
    Commented May 24, 2016 at 16:41

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