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

Problem:

You may get the following error (or) similar to that, when try to start nginx,

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

Reason:

nginx or some other process is already using port 80.

Fix:

You can kill the process by running the below command,

# fuser -k 80/tcp

And then restart nginx

# service nginx start