nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)

Not really a tutorial, but more about solving problem.

Problem : Try to start nginx after a hard reboot and got this error message

nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)

After some investigation, apparently it was caused by a process which is already using port 80.

Later on, I found out that it was caused by auto start of nginx.

To fix this problem, just stop nginx

service nginx stop

and restart nginx

service nginx start

this solved my problem. However,in case it is not caused by nginx. You can do this

sudo fuser -k 80/tcp

to kill the process that hogged port 80.

Oh! Before killing the process. Make sure you know which process it is first!