kill port already linux code example
Example 1: kill app at port
#To list any process listening to the port 8080:
lsof -i:8080
#To kill any process listening to the port 8080:
kill $(lsof -t -i:8080)
#or more violently:
kill -9 $(lsof -t -i:8080)
Example 2: kill process on port
lsof -i:3000 // Change 3000 to whatever your port is!
sudo kill 9 <PID> // Change <PID> to the Pid number the above command returns