Kill processes running on specific ports


The Problem

you had a couple of node.js apps running from you terminal and you closed the tabs. You opened a new terminal tan, tried to npm run dev and got hit with a EADDRINUSE error. You could run ps and try to figure out which jobs are your node apps.

The solution

One thing you do know is what ports these apps are listening/running on.

lsof Lists open files and the corresponding processes. There are 2 options werer interested in here:

  • -t to only get the process id
  • -i:{port||3000||8080} to get the process that opened a specific port (you can "daisy chain" the -i option)

So when we execute lsof -t -i:3000 -i:8080 in our shell we should get 2 pids. Cool.

We can pipe (|) the output of this command to xargs and the kill command like so:

lsof -t -i:8080 -i:3000 | xargs -n1 sh -c 'kill -9 $0'

A quick breakdown:

  • xargs -n1: number of argument (1 in this case)
  • sh -c 'kill -9 $0' : instruct sh to run the following command and replace $0 with value from xargs

this also works

lsof -t -i:8080 -i:3000 | xargs -i % sh -c 'kill -9 %'