free-clamshell-mode

Minimal macOS menu bar app that keeps your Mac awake with the lid closed — no AC power required.

Requirements

• macOS 11.0+
• Swift 5.5+
• Terminal

Build

bash build.sh

Output: build/free-clamshell-mode.app

Install (optional)

cp -r build/free-clamshell-mode.app ~/Applications/

Then open the app and enable Settings > Launch at Login.

Usage

1. Build and open the app
2. Clam shell icon appears in the menu bar
3. Left-click the icon to toggle on/off
4. Right-click (or Ctrl+click) to open the menu

The icon turns into a green scallop fan when active.

How It Works

Uses sudo pmset -a disablesleep 1 to prevent the system from sleeping when the lid is closed, regardless of power source.

State	Command
Enable	sudo pmset -a disablesleep 1
Disable	sudo pmset -a disablesleep 0

Admin Password — First Time Only

On first activation the app writes a sudoers rule so pmset can run password-free on all future uses:

/etc/sudoers.d/free-clamshell-mode
<username> ALL=(ALL) NOPASSWD: /usr/bin/pmset

You will see a macOS admin password dialog once. After that, no password is ever needed again — even after restarts.

To remove this permission manually:

sudo rm /etc/sudoers.d/free-clamshell-mode

Settings

Setting	Default	Description
Launch at Login	Off	Auto-start on login via SMAppService
Hide from Dock	On	App appears only in the menu bar
Show Warnings	On	Confirm dialog before enabling

Important: Force Quit Behavior

If the app is force-quit while active, disablesleep remains set to 1. Restore normal sleep behavior manually:

sudo pmset -a disablesleep 0

A clean quit (Cmd+Q or Quit from the menu) always resets disablesleep to 0 automatically.

Troubleshooting

macOS blocks app after rebuild (code signature mismatch):

codesign --remove-signature build/free-clamshell-mode.app

"Permission denied":

chmod +x build/free-clamshell-mode.app/Contents/MacOS/free-clamshell-mode

"Compilation failed":

xcode-select --install

pmset disablesleep stuck at 1:

sudo pmset -a disablesleep 0