Hold up, don't modify important system files!

Mac OS has a nice way to start/stop services without doing permanent damage.

To turn off bezels for this user until next login:

launchctl unload -F /System/Library/LaunchAgents/com.apple.BezelUI.plist

To undo, change unload to load , or just log out and back in.

For macOS 10.12 Sierra: Disable System Integrity protection, then:

launchctl unload -F /System/Library/LaunchAgents/com.apple.OSDUIHelper.plist

Don't forget to enable System Integrity protection when you're done.

To turn off bezels indefinitely for this user:

launchctl unload -wF /System/Library/LaunchAgents/com.apple.BezelUI.plist

For macOS 10.12 Sierra: Disable System Integrity protection, then:

launchctl unload -wF /System/Library/LaunchAgents/com.apple.OSDUIHelper.plist

You can now enable System Integrity protection again -- your settings will persist.

To undo, change unload to load .

To turn off bezels indefinitely for all users:

sudo defaults write /System/Library/LaunchAgents/com.apple.BezelUI Disabled -bool YES

For macOS 10.11 Sierra: Disable System Integrity protection before doing the above.

To undo, change YES to NO , or:

sudo defaults delete /System/Library/LaunchAgents/com.apple.BezelUI Disabled

For macOS 10.12 Sierra: Disable System Integrity protection, then:

sudo defaults write /System/Library/LaunchAgents/com.apple.OSDUIHelper Disabled -bool YES

You can now enable System Integrity protection again -- your settings will persist.

To undo, change YES to NO , or:

sudo defaults delete /System/Library/LaunchAgents/com.apple.OSDUIHelper Disabled

Users can override this global setting using the two methods above.

More info: launchctl is the command-line interface to launchd, the program that manages services and jobs on Mac OS.

To reverse any of the above actions, just change unload to load .

to . -w means w rite preference to disk so that it will be used for subsequent logins

means rite preference to disk so that it will be used for subsequent logins -F means force un/load regardless of the global Disabled key