First, run the following command to show processes running with the given port opened:
lsof -i tcp:3001
This will output something like this:
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME node 4320 mroma 19u IPv6 37934 0t0 TCP *:3001 (LISTEN)
Once you find the process, use the command below to kill it:
kill 4320
You can use the following command to find and kill at the same time by parsing the results with awk
lsof -i tcp:3000 | awk ‘{system(“kill -9 ” $2)}’