Scieneer Common Lisp 1.3.9 online documentation

ext:process-kill process signal &optional whom[Function]

Send the signal to process. The signal should be a valid signal number or a keyword of the standard UNIX signal name. If whom is :pid then send the signal to the process, or if whom is :process-group then send the signal to the process's group. Return true upon success otherwise nil and an error number.