EADDRINUSE - kill process at a specific port

It happens sometimes that an address in use is not released. For example, when we restart our IDE after an update or accidentally close the IDE without shutting down the server. In these cases, we encounter the below error:

    Error: listen EADDRINUSE 0.0.0.0:4000
  

saying address already in use. In linux, there is a utility to release the port by killing the process that is using it.

    $ fuser -k 4000/tcp 4000/tcp: 9032
  

It finds the user by the 4000 port with protocol tcp, kills it and outputs the pid (process id). If you do not supply the -k, it simply outputs the pid.