How do I kill the process currently using a port on localhost in ubuntu code example

Example 1: kill port ubuntu

sudo kill -9 `sudo lsof -t -i:9001`

Example 2: kill process at a port ubuntu

sudo kill -9 $(sudo lsof -t -i:9001)

Example 3: ubuntu kill process on a port

sudo kill -9 $(sudo lsof -t -i:4000)