The syslog-ng 3.0 Administrator Guide

Starting from version 3.0, syslog-ng can handle embedded log statements (also called log pipes). Embedded log statements are useful for creating complex, multi-level log paths with several destinations and use filters, parsers, and rewrite rules.

For example, if you want to filter your incoming messages based on the facility parameter, and then use further filters to send messages arriving from different hosts to different destinations, you would use embedded log statements.

Figure 2.2. Embedded log statement

Embedded log statements include sources — and usually filters, parsers, rewrite rules, or destinations — and other log statements that can include filters, parsers, rewrite rules, and destinations. The following rules apply to embedded log statements:

Figure 2.3. Embedded log statements

Embedded log filters can be used to optimize the processing of log messages, for example, to re-use the results of filtering and rewriting operations.