Find (and kill) process locking port 3000 on Mac

Question

How do I find (and kill) processes that listen to/use my tcp ports? I'm on mac os x.

Sometimes, after a crash or some bug, my rails app is locking port 3000. I can't find it using ps -ef...

When doing

rails server

I get

Address already in use - bind(2) (Errno::EADDRINUSE)

2014 update:

To complete some of the answers below: After executing the kill commands, deleting the pid file might be necessary rm ~/mypath/myrailsapp/tmp/pids/server.pid

Answer 1

1. You can try netstat

    netstat -vanp tcp | grep 3000
   

2. For macOS El Capitan and newer (or if your netstat doesn't support -p), use lsof

    lsof -i tcp:3000 
   

3. For Centos 7 use:

    netstat -vanp --tcp | grep 3000