Address already in use Damn. Did I leave a server running somewhere? Sometimes you’re not sure where you left a server running, or where something is running you never knew about. I’m finally writing this down, as I always have to look it up. I found this solution in a StackOverflow post. Here’s how to get all of the processes by what port they’re using. sudo lsof -iTCP -sTCP:LISTEN -n -P As A Shell Function Looking at it, I realized I would never remember it, given how infrequently I need it.