When using Splunk Web to configure a new Powershell v3 Modular Input the hint for the Cron Schedule the hint text states A cron string specifying the schedule for execution: seconds minutes hours days-of-month month days-of-week years but this does not seem to be a valid Cron expression. What syntax is supported by Splunk for this feature. I am using Splunk 6.3.1.
I'm asking this question so I can document the answer that I have found for easy future reference.
Quartz Scheduler Format, not Unix Standard. The doc has examples.
From trial and error, it seems that the cron expression supported here is the same as for scheduled alerts:
and that is the 5 field version corresponding to correspond to minute hour day-of-month month day-of-week. See the Wikipedia entry for Cron for details:
I suspect the incorrect hint text comes from the fact that there is also a Splunk Add-on for Microsoft PowerShell (https://splunkbase.splunk.com/app/1477/) that was implemented using Quartz.net (http://www.quartz-scheduler.net/) which has a different cron expression syntax for cron triggers (http://www.quartz-scheduler.net/documentation/quartz-2.x/tutorial/crontriggers.html ).
It seems that the built-in PowerShell v3 Modular Input that comes with Splunk 6.3+ shares the same implementation as as other parts of the Splunk platform. The documentation for the PowerShell Modular Input: http://docs.splunk.com/Documentation/Splunk/6.5.0/Data/MonitorWindowsdatawithPowerShellscripts uses the correct format for the examples although is still incorrectly includes a link to the Quartz.net implementation.
It makes sense that Splunk would not want you to be triggering these scripts with a more granular time scale than minutes so the lack of seconds support seems to fit.