How can I check which ports are in use from the Linux command line?

Question

I'm running a Node.JS application and need to figure out if something is using a certain port.

How can I do this from the linux command line?

Answer 1

There must be a more elegant way, but when in a hurry, I just run netstat | grep port_number

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Yes, there are more elegant ways...

Linux List The Open Ports And The Process That Owns Them

sudo lsof -i
sudo netstat -lptu
sudo netstat -tulpn