The standard logging protocol on Unix and related systems is called Syslog. Most modern Linux distributions use an implementation such as Rsyslog or Syslog-NG. They all perform the same tasks:
Allow software running on your system to send Syslog messages
Separate incoming messages by type and priority and save them to different files
Most system utilities send log messages to Syslog, but other server software (such as Apache, MySQL, or PostgreSQL), by default, save messages directly to files on disk.
Webmin allows you to control Syslog and decide which messages get saved to which files. In order to understand how Syslog separates messages, we need to explain two concepts: facilities and priorities.
Each message sent to Syslog is described by a facility level and priority level. Based on these properties, you can decide which messages to discard, which to save, and where.
A facility level describes what type of message this is. Since programs usually send all...