Each line of the file specifies the type of message to log and the destination where the message will be logged. The type of message consists of two parts separated by a period. The first part specifies the facility that generated the message. The second part specifies priority of the message. The following example shows typical lines found in the system log.
All proxy servers write messages to the system log.
Each proxy server message contains the name of the proxy server to identify the source of the message. This can be used to search for messages issued by a specific program on a specified date. UNIX provides simple commands that allow the systems administrator to customize reports based on system log data. The data can be examined by date, type of service or type of message. The following sections show how you can use basic UNIX commands to examine system activity.