My Linux Notebook

Have you ever had a problem when you tried to start a process and you got an error that a port which the process needs is already used by another process?

How to display open network ports in Linux

With netstat, the network statistics command line tool, you can list all the open ports on your Linux with the process id of the process which opened them.

$ netstat -lp


The -l option, display listening server sockets.
The -p option, display PID/Program name for socket.

If you want to see which process uses port 80 all you need to do is to combine the netstat command with grep.

$ netstat -lp | grep 80