When Force Quit Fails
When an application on macOS freezes completely, the standard operating procedure is to right-click its icon in the Dock and hold the Option key to reveal the hidden Force Quit button. Alternatively, you can press Command + Option + Escape to bring up the Force Quit Applications window.
However, occasionally a background process, a menu bar utility, or a deeply hung application will refuse to respond even to the Force Quit GUI. When the graphical interface fails, you must drop down to the Terminal and forcefully terminate the process at the UNIX kernel level using the killall command.
Using the killall Command
The killall utility is incredibly dangerous but highly effective. It searches the active process table for a specific application name and sends a termination signal (SIGTERM) directly to it, instantly killing the program and all of its associated child processes.
- Open the Terminal application (found in Applications > Utilities, or via Spotlight).
- Type
killallfollowed by the exact, case-sensitive name of the application. For example, to forcefully close Safari:
killall Safari- Press Enter. The application will instantly vanish from your screen.
The Case-Sensitivity Trap
The most common error users make with killall is forgetting that macOS process names are strictly case-sensitive. If you type killall safari (lowercase ‘s’), the terminal will return an error stating No matching processes belonging to you were found.
If you have an application with a space in its name (like “Google Chrome”), you must enclose the entire name in quotation marks, otherwise the command will attempt to kill a process named “Google” and a process named “Chrome.”
killall "Google Chrome"The Nuclear Option (SIGKILL)
By default, killall sends a gentle SIGTERM (Signal 15), asking the application to shut down gracefully. A severely hung application might ignore this polite request.
To forcefully execute the process without giving it any chance to save data or clean up its memory, you must send a SIGKILL (Signal 9). You do this by appending the -9 flag to the command.
killall -9 "Final Cut Pro"Use the -9 flag with extreme caution. It will instantly destroy the application, and any unsaved work in that program will be permanently lost.