To verify the configs, the docs state:
/usr/local/nagios/bin/nagios -v <main_config_file>
That is from the docs. You stated you ran verify like this:
/usr/local/nagios/bin/nagios -v nagios.cfg
Where is nagios.cfg located? It should have been the full path to the .cfg like this:
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
From the docs, nagios is started manually like this:
/usr/local/nagios/bin/nagios <main_config_file>
In most case that would be:
/usr/local/nagios/bin/nagios /usr/local/nagios/etc/nagios.cfg
But you stated you started nagios like this:
/usr/local/nagios/bin/nagios nagios.cfg
Which is not the way to start nagios. How is it going to find nagios.cfg?