It is a general command to check which program is using port 80. And also known the PID of this process. Then to force stop it and release the port 80 to other program.
root@ubuntu:~# lsof -i:80 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME apache2 1314 root 4u IPv6 9663 0t0 TCP *:http (LISTEN) apache2 2582 www-data 4u IPv6 9663 0t0 TCP *:http (LISTEN) apache2 4464 www-data 4u IPv6 9663 0t0 TCP *:http (LISTEN) apache2 9980 www-data 4u IPv6 9663 0t0 TCP *:http (LISTEN) apache2 9982 www-data 4u IPv6 9663 0t0 TCP *:http (LISTEN) apache2 10120 www-data 4u IPv6 9663 0t0 TCP *:http (LISTEN) apache2 10147 www-data 4u IPv6 9663 0t0 TCP *:http (LISTEN) apache2 10282 www-data 4u IPv6 9663 0t0 TCP *:http (LISTEN) apache2 10283 www-data 4u IPv6 9663 0t0 TCP *:http (LISTEN) apache2 10543 www-data 4u IPv6 9663 0t0 TCP *:http (LISTEN) apache2 10544 www-data 4u IPv6 9663 0t0 TCP *:http (LISTEN)
To get more details of how to use command lsof, enter lsof –help to get the help.
