#First run this, to get port information (with the port you want to kill) sudo lsof -i :3000 #Then run this, with <PID> replaced by the value in the column returned by previous command. kill -9 <PID>
sudo lsof -i :3000
$ lsof -nP -iTCP -sTCP:LISTEN | grep 8000
sudo lsof -PiTCP -sTCP:LISTEN