System Logging

The ChorusOS operating system provides a general message logging feature (syslog) which is used by the microkernel and applications. This logging feature provides support for logging console activity on a target system and provides a way to store information kept on persistent storage (disk).

The Syslog feature consists of a logging server (syslogd) and a device into which messages are written. Distribution of messages is controlled by the configuration file syslog.conf. The syslog APIs enable applications to send messages to the syslog.

System logging enables the microkernel and other applications to produce error, warning, and other messages. The messages are saved in a file in append-only mode and can be viewed at a later time. Log file data are never overwritten. The logging service modifies the file by appending new data.

To use the system logging feature, an application writes log messages tagged with a specific header (including the facility and the severity). These messages are then sent to the logging service. The local configuration of the logging service defines how the messages are processed. The criteria used to select how a message is processed are based on the values in the Facility and/or Severity fields.

A message can be:

• discarded (filtered out)

• appended to a local file

• forwarded to another node where it will be stored in a file