To get a list of all listening TCP ports with lsof type: sudo lsof -nP -iTCP -sTCP:LISTEN
The options used are as follows: -n - Do not convert port numbers to port names. -p - Do not resolve hostnames, show numerical addresses. -iTCP -sTCP:LISTEN - Show only network files with TCP state LISTEN.
Check particular Port: sudo lsof -nP -iTCP:3306 -sTCP:LISTEN
Use netstat - To locate specific port sudo netstat -ap | grep
Sample sudo netstat -ap | grep 8123 tcp 0 0 localhost:8123 0.0.0.0:* LISTEN 9257/node
To kill the port kill which locate with /... from the sample it is 9257
Sample to kill port kill 9257