Configuration nagios

salut tout le monde
j'ai un problème de configuration des objets sur nagios
je n'ai pas trouvé les fichiers
/usr/local/nagios/etc/objects/hostclients.cfg
cfg_file=/usr/local/nagios/etc/objects/hostgroups.cfg
alors j'ai modifié le fichier localhost.cfg

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#
# HOST DEFINITION
#
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# Define a host for the local machine

define host{
        use                     linux-server            ; Name of host template to use
							; This host definition will inherit all variables that are defined
							; in (or inherited by) the linux-server host template definition.
        host_name               rach-desktop
        alias                   localhost
        address                 192.168.0.4
        }
define host{
        use                     ima           ; Name of host template to use
							; This host definition will inherit all variables that are defined
							; in (or inherited by) the linux-server host template definition.
        host_name               ima-desktop
        alias                   ubuntu
        address                 192.168.0.3
        }




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#
# HOST GROUP DEFINITION
#
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# Define an optional hostgroup for Linux machines

define hostgroup{
        hostgroup_name  linux-servers ; The name of the hostgroup
        alias           Linux Servers ; Long name of the group
        members         rach-desktop, ima-desktop     ; Comma separated list of hosts that belong to this group
        }



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puis aller consulter la page http://localhost/nagios/ j'ai remarqué que message d'erreur

Whoops!

Error: Could not read host and service status information!

The most common cause of this error message (especially for new users), is the fact that Nagios is not actually running. If Nagios is indeed not running, this is a normal error message. It simply indicates that the CGIs could not obtain the current status of hosts and services that are being monitored. If you've just installed things, make sure you read the documentation on starting Nagios.

Some other things you should check in order to resolve this error include:

   1. Check the Nagios log file for messages relating to startup or status data errors.
   2. Always verify configuration options using the -v command-line option before starting or restarting Nagios! 

Make sure you read the documentation on installing, configuring and running Nagios thoroughly before continuing. If all else fails, try sending a message to one of the mailing lists. More information can be found at https://www.nagios.org/

merci d'avance