How to find PID of process listening on a port in Linux? netstat and lsof command examples

In Linux, many times, you want to find out the PID of a process which are listening on a port e.g. if multiple tomcat serversare running on a host then, how do you find the PID of the tomcat listening on port 8080? There are many UNIX commands to find the process using a specific port, but I’ll share what I use.