<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body text="#000000" bgcolor="#ffffff"> Often, when you're getting an error and the only result you see is (null), what is happening is that your check script is printing to stderr. It might be that you have perl in your path, but the perl script's #! line doesn't declare the full path to perl, or there's an access error of some sort. But it's easy to figure out what's going on. Simply change your command_line to: command_line $USER1$/check_apc_pdu.pl -H $HOSTADDRESS$ -C public 2>&1 That will redirect standard error to standard out. Next time Nagios runs the script it will capture the full output of the script and you should see right in your Nagios ui, what the issue is. Sun, Mar 27, 2011 at 2:45 PM, Peter Roddan <<a moz-do-not-send="true" href="mailto:Peter.Roddan@sbsworldwide.com">Peter.Roddan@sbsworldwide.com</a>> wrote:<o:p></o:p> <blockquote cite="mid:4AF89336841CA740B4338F482A8FC74C11BA6D74D0@message-drt.sbsworldwide.com" type="cite"> <div class="WordSection1"> <div> <div> <div>If I log onto the nagios server as the nagios user, and run the command from the libexec folder (check_apc_pdu –H <address> -C public) I get the response :<o:p></o:p> <o:p></o:p> “OK: All Outlets ok. | load=25”<o:p></o:p> I have put the following command definition in :<o:p></o:p> # 'check_apc_pdu' command definition<o:p></o:p> define command{<o:p></o:p> command_name check_apc_pdu<o:p></o:p> command_line $USER1$/<a moz-do-not-send="true" href="http://check_apc_pdu.pl" target="_blank">check_apc_pdu.pl</a> -H $HOSTADDRESS$ -C public<o:p></o:p> }<o:p></o:p> <o:p></o:p> And defined the following service <o:p></o:p> <o:p></o:p> define service{<o:p></o:p> use generic-service ; Inherit values from a template<o:p></o:p> hostgroup_name apc ; The name of the host the service is associated with<o:p></o:p> service_description check_apc ; The service description<o:p></o:p> check_command check_apc_pdu ; The command used to monitor the service<o:p></o:p> normal_check_interval 5 ; Check the service every 5 minutes under normal conditions<o:p></o:p> retry_check_interval 1 ; Re-check the service every minute until its final/hard state is determined<o:p></o:p> }<o:p></o:p> <o:p></o:p> <o:p></o:p> However, my APC PDUs report an error for this service, with a status information of “(Null)”<o:p></o:p> I’d be grateful for anyone who could point me in the right direction of where I’m going wrong.<o:p></o:p> </div> </div> </div> </div> </blockquote> <pre class="moz-signature" cols="72">-- Mike Lindsey</pre> </body> </html>