Clamshell 4+

Initiate actions when clamshell state changes

Clamshell is a tiny app that can run following actions when the clamshell (laptop lid) is closed:


‣ Sleep
‣ Shut Down
‣ Turn Off Displays & Prevent Idle Sleep
‣ Keep External Displays On & Prevent Idle Sleep


Sleep causes an immediate system sleep when your MacBook closes. It is very useful for users who use MacBook with external displays connected. When your MacBook connected to the power, Sleep will turn off a built-in display and all external displays, and the system will enter an idle sleep mode. If there are processes that hold assertions to prevent idle sleep, the system will wait before sleep with turned off displays while these processes are running. When your MacBook runs on battery, Sleep mimics the system default behavior because it cannot be altered by user apps.


Shut Down initiates swift and unavoidable system shutdown when the lid of your MacBook closes. No questions asked. This mode is useful, if you work on MacBook in the unsafe public places, such as parks, cafes, bus stations, etc. Mac will shut down automatically when lid closes, preventing anyone to bypass password protection with Touch ID/ Face ID, and preventing some advanced hacking techniques, such as cold boot attack, dumping RAM and circumventing FileVault. This mode also helpful, if your MacBook awakes often in your backpack.


Turn Off Displays & Prevent Idle Sleep puts all displays in the sleep mode and creates a power assertion preventing the rest of the system entering an idle sleep. This mode is useful for users who use MacBook with external displays connected. When you close the lid of your Mac connected to the power, a built-in display and all external displays go black but running applications remain working in the background, such as Music keeps playing, Safari keeps downloading big file, etc. When your MacBook runs on battery, Turn Off Displays & Prevent Idle Sleep mimics the system default behavior, i.e. a simple Sleep.


Keep External Displays On & Prevent Idle Sleep creates two power assertions preventing external displays and the rest of the system entering an idle sleep. If some display is off, this action turns it on.


Note for users of iMac, Mac mini, Mac Studio and Mac Pro: Clamshell is useless if there is no clamshell ;)


Please stay tuned for updates. More actions to come.