Address already in use

finding port of address already in use

  $ sudo netstat -nlp | grep 80
  tcp  0  0  0.0.0.0:80  0.0.0.0:*  LISTEN  125004/nginx

or

 # sudo lsof -i :25
 COMMAND  PID        USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
 exim4   2799 Debian-exim    3u  IPv4   6645      0t0  TCP localhost:smtp (LISTEN)
 exim4   2799 Debian-exim    4u  IPv6   6646      0t0  TCP localhost:smtp (LISTEN)