If you only using one ip, you can use listen 80 default;
The some_ip:some_port is using on my product server, it shows no problem.

2011/9/10 ynasser <nginx-forum@nginx.us>

> I don't think it's a problem with reloading the configuration file,
> because I have been reloading it every time after I update and save it.
>
> What is happening is that when I run 'sudo nginx', it doesn't start and
> outputs this error:
>
> nginx: [emerg] bind() to some_ip:some_port failed (49: Can't assign
> requested address)
>
> I can access some_ip:some_port just fine from a browser and ssh-ing into
> it is not a problem.
>
> Posted at Nginx Forum:
> http://forum.nginx.org/read.php?2,214982,215044#msg-215044
>
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