What is the function of host_regex?

[dkr3500]

In our Splunk forwarder, in the path: /opt/splunk/etc/apps/app01/default we have many stanzas such as:

[monitor:///export/data/syslog-ng/sentry*/messages]
disabled   = false
host_regex = /export/data/syslog-ng/(.*?)/messages
index      = asalg
sourcetype = cisco_asa

And under every stanza there is the following line:

host_regex = /export/data/syslog-ng/(.*?)/messages

I am very curious to know what the "/(.*?)/" means?

Thank you.

[FrankVl · Accepted solution]

The host_regex is used to extract the hostname from the monitored path. In regular expressions (...) denotes a capturing group, so that is what actually captures the hostname, from that part of the path. The .*? means that it accepts all kinds of characters for the hostname, but using the ? it only captures things until it actually finds something that matches what comes after the ?. In this case the "/messages" bit.

[dkr3500]

Thanks FriankVI !