Linux: How to check a particular port is already being used by some executable ?

Question

I was running a binary and in between network went down. Process was still running with its parent "1".
I re-logged into the system and find the running process and trigger $ kill -9 . After doing that I was trying to rerun the binary but it was not working with error message "Port is already being used" but I again checked there was no binary with such name. How I can resolve such issue ? Please help me .

Answer 1

netstat command to find open ports

$ netstat --listen

To display open ports and established TCP connections, enter:

$ netstat -vatn

To display only open UDP ports try the following command:

$ netstat -vaun

Display PID and program names in netstat output

$ netstat -pt

Check the following link for more specific need: http://www.thegeekstuff.com/2010/03/netstat-command-examples/