SHELL

list used ports on mac

sudo lsof -PiTCP -sTCP:LISTEN

COMMAND     PID      USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
GitHub      850 grgarside   6u   IPv4 0x23c345381d089301      0t0  TCP localhost:25035 (LISTEN)

mac list used port

sudo lsof -i -P | grep LISTEN

mac list used port

sudo lsof -nP -i4TCP:$PORT | grep LISTEN

mac list used port

sudo lsof -nP -iTCP:$PORT | grep LISTEN
sudo lsof -nP -i:$PORT | grep LISTEN