Regexp in log item creates log entry twice

[Baymon]

Hi,

i monitor a logfile, a line in the logfile looks like this:

2022-07-18 14:50:41-[HOSTNAME] This is the message

My item key looks like this:

log[/var/log/zabbix/monitor.log,".HOSTNAME. This is the message"]

This wokrs perfect, it gives me one match with one entry in the Zabbix Latest data log

In order to exactly match the line i modified the item like this:

log[/var/log/zabbix/monitor.log,"^(.HOSTNAME. This is the message)$"]

This should not match at all because the timestamp is missing. But anyhow, i get log entries in the Latest data and with this item i have exactly the same log entry twice. What is going wrong here?

[Baymon]

After some tests with https://regex101.com/ i found out, the double match is because of a normal match and a group match.

[dimir]

Yeah, you should have specified the output:

log[/var/log/zabbix/monitor.log,".*(.HOSTNAME. This is the message).*",,,,"\1"]