Address already in use

Sometimes, you find yourself with a local web server running, but having lost the console session where you started it, so you can't ctrl-c to stop it. Maybe you closed the tab, or the terminal crashed leaving the server running. When you try to start the server again you an error like Address already in use, or A server is already running.

For a long time I didn't really have a solution for this, it didn't happen very frequently so I just started the server on a different port and moved on with my life.

Some time ago I finally did the research and came up with a better solution. It is a very simple bash script that simply kills whichever process that listens to the port you give it, I call it portkill - Here it is in action:

It gets the id of the process listening on the port using lsof -t -i:4000, then simply kills that process. Here is the source of portkill, with a tiny bit of error handling.