apache server not restarting in ubuntu 14.04 - apache

Question

When I am trying to restart the apache2 services with sudo service apache2 restart command, I am getting this error.
(98)Address already in use: AH00072: make_sock: could not bind to
address [::]:80 (98)Address already in use: AH00072: make_sock: could
not bind to address 0.0.0.0:80 no listening sockets available,
shutting down AH00015: Unable to open logs Action 'start' failed. The
Apache error log may have more information.
So I added ServerName localhost in my apache2.conf file and then tried to restart the apache2 service. I am getting the same above error.
Please help.

Answer 1

There are two reasons why this problem exists:
1. Multiple ‘Listen’ Directive Entries Existing in Configuration Files. (Solution below)
Hit grep Listen /etc/apache2/ports.conf
Check if you are getting something like:
Listen 80
Listen 81
Listen 80
Listen 443
Listen 443
The error log could not bind to address 0.0.0.0:80 mentions its an issue with the port 80. Hence edit the file and remove the duplicate.
2. Another Process is Already Using Port 80
Hit : fuser -n tcp 80 along with ps aux | grep PID or hit
ss -plnt sport eq :80
and kill the processes.

Answer 2

You probably have a process that's still using it. You can do
pidof apache2
The last pid in the list is the main process you can kill.
or you can do
netstat -anp | grep :80 | grep -i listen
Then on the right hand side of the line, that it outputs you'll see the PID.
or you can do
lsof -i :80
Then the top apache process is the one you'll want to kill. Which is the number in the 2nd column output.
Then whenver you have the main pid from one of these commands use this.
kill -9 <pid> e.g. kill -9 12345