Finding the PID listening to a port

Question

I use a bash script to run both the frontend and the backend of my full-stack application on macOS:

#!/usr/bin/env bash

export PORT="3001"
export API_PORT="5001"
export MAIN_URL="http://localhost:"

cd Client
npm run dev &
cd ..
nodemon index.js &

The issue is that I want to kill the PID listening to the port before I execute the npm and nodemon commands. Is there a way I can get the specific PID? Can I write the listening PID to a .pid file and then read from it when I want to kill?

You coul use `netstat -tanlp` or search from `/proc/net/dev`.... — F. Hauri - Give Up GitHub, Nov 01 '21 at 13:48
At this moment, this question has 0 upvotes, 0 downvotes, 2 answers, 2 comments trying to answer, and 2 close votes for _Seeking recommendations for books, tools, software libraries, and more_. — user1717828, Nov 01 '21 at 22:25
Does this answer your question? [Find (and kill) process locking port 3000 on Mac](https://stackoverflow.com/questions/3855127/find-and-kill-process-locking-port-3000-on-mac) — , Nov 04 '21 at 01:00

score 1 · Accepted Answer · 2021-11-04T13:08:08.057

1

Try this:

pid=$(sudo lsof -i :3001 -t)
kill $pid

edited Nov 04 '21 at 13:08

answered Nov 01 '21 at 22:04

1

this works! thanks (no need for the sudo) – TheMachineX Nov 02 '21 at 06:41
1

You want to avoid the [useless `grep`](https://www.iki.fi/era/unix/award.html#grep); you can refactor to just `sudo lsof -i :3001 -F | sed -n 's/^p//p'` ... but of course with `lsof -t` you don't need the pipe at all. – tripleee Nov 04 '21 at 08:05

Finding the PID listening to a port

1 Answers1