find ports in terminal code example

Example 1: linux how to see ports in use

# Any of the following
sudo lsof -i -P -n | grep LISTEN
sudo netstat -tulpn | grep LISTEN
sudo lsof -i:22 # see a specific port such as 22
sudo nmap -sTU -O IP-address-Here

Example 2: check all the ports in use mac

$ npx kill-port 3000 8080 8081

Process on port 3000 killed
Process on port 8080 killed
Process on port 8081 killed