Debug logs are a great way to track down problems when you've exhausted your normal troubleshooting avenues.
Turn On Debugging
This sets debugging to output the most information.
Command:
sed -i 's/.*debug_level=.*/debug_level=-1/g' /usr/local/nagios/etc/nagios.cfg
service nagios restart
Turn Off Debugging
This turns debugging off.
Command:
sed -i 's/.*debug_level=.*/debug_level=0/g' /usr/local/nagios/etc/nagios.cfg
service nagios restart
Watch The Debug Log
When debugging is enabled you can watch the log live.
Command:
tail -f /usr/local/nagios/var/nagios.debug
You can also filter the output so it only shows items that contain strings you are interested in. The followin example will only output lines that contain the word "flapping":
Command:
tail -f /usr/local/nagios/var/nagios.debug | grep flapping
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