$ sudo service nagios start Starting nagios:No directory, logging in with HOME=/ done.
I found this message was same-produced when I switched to user "nagios". It was caused there was no home directory for user "nagios". This script created the user "nagios" with no home directory during running to own nagios-core's home directory and start its daemon.
$ sudo su - nagios No directory, logging in with HOME=/
To do solve this, it just make home directory for that user
# Make a directory and changed the ownership $ sudo mkdir /home/nagios $ sudo chown -R nagios:nagios /home/nagios # Setting the directory as the home of nagios $ sudo usermod --home /home/nagios nagios usermod: no changes # Restarting nagios daemon, this time there is no above message $ sudo service nagios restart Running configuration check...done. Stopping nagios: done. Starting nagios: done.