Every time you modify your configuration files, you also have to restart Icinga. It is important to run a sanity check on your configuration files because in case of an error Icinga will not be (re)started.
In order to verify your configuration, run Icinga using the -v command line option:
/usr/local/icinga/bin/icinga -v /usr/local/icinga/etc/icinga.cfg
If you've forgotten to enter some critical data or misconfigured things, Icinga will show a warning or error message that should point you to the location of the problem.
Error messages generally print out the line in the configuration file that seems to be the source of the problem.
On errors, Icinga will often exit the pre-flight check and return to the command prompt after printing only the first error that it has encountered.
This is done because one error might lead to consecutive errors as the remainder of the configuration data is verified.
If you get any error messages you'll need to go and edit your configuration files to remedy the problem. Warning messages can generally be safely ignored, since they are only recommendations and not requirements.
Once you've verified your configuration files and fixed possible errors you can go ahead with “Starting and Stopping Icinga”.
© 2009 Icinga Development Team, http://www.icinga.org