You could do a regex on this.

filter f_group {
host('^(?<GROUP>group.)' type('pcre') flags('store-matches'));
};
destination d_group {
file("/log/$GROUP/$HOST");
};
log { source(s_local); filter(f_group); destination(d_group); };

Sent: Fri Jul 22 2011 11:55:38 GMT-0600 (MST)
From: Jakub Jankowski <shasta@toxcorp.com>
To: syslog-ng@lists.balabit.hu
Subject: Re: [syslog-ng] can syslog-ng extract part of the hostname and make directory on the fly?

On Fri, 22 Jul 2011 09:28:35 -0500, fedora fedora wrote:

I have few hundreds of hosts, and say

hosta has dns name groupa-hosta
hostb has dns name groupbhostb
hostc has dns name groupc.hostc

..etc..etc (note the first 6 characters defines the group)

When a log comes in, can syslog-ng extracts the first 6 character from dns
name, and drop the log file to the corresponding group? (So log from hostb
will go under /log/groupb/groupahostb )

I cannot predefine the groups though, since i don't know how many groups
will be there, the only thing i know is the first 6 character of the
hostname will be the group name

If there was a distinct separator between the group name and the rest, this
would be trivial, see similar example in 3.2 OSE administrator guide:
http://www.balabit.com/sites/default/files/documents/syslog-ng-ose-v3.2-guide-admin-en.html/index.html-single.html#example_parser

Without such separator, I think you'd have to use something I asked for: a
substring function. This isn't included in 3.2 yet, but you can backport it
quite easily (I'm using it without problems). See those threads:
https://lists.balabit.hu/pipermail/syslog-ng/2011-April/016329.html
https://lists.balabit.hu/pipermail/syslog-ng/2011-April/016359.html
https://lists.balabit.hu/pipermail/syslog-ng/2011-May/016502.html


HTH