The document discusses syslog, the standard for logging program messages and events from both applications and the kernel to files or remote hosts. It covers how syslog works, how to configure syslog by modifying the syslog.conf file to define log sources and destinations, and provides examples of logging priority levels and using utilities like logger and logrotate to manage logs.

1. Syslogsangjung.woo@gmail.com

2. SyslogStandardfor logging program messagesGenerating log from both kernel and appStoring log into files, named pipes, remote hosts and specific usersBoth of themprintk/klog for kernel eventsyslogd for app event

3. Syslog usageJava App 1Java App 2MusicVideo PlayerMultimedia FWJVMKernel- Critical Message- Warning- Information- *(Everything)- Critical Message- Warning- Information

4. Syslog configurationSyslogd default conf file/etc/syslog.confSelector + ActionSector: Facility + PriorityAction: Write destination

5. Syslog configuration – con’dPriority (/usr/include/sys/syslog.h)emergalertcriterrwarningnoticeInfodebug

6. Syslog configuration – con’dPredefined facility (/usr/include/sys/syslog.h)kernmaildeamonauthnewsftpuser0~user7

7. SyslogdRestart syslog daemonsudo /etc/init.d/sysklogdrestart/etc/init.d/sysklogd status

8. ExampleModify syslog.confUser level code

9. Example – con’dLog message

10. ExtensionSyslog configurationlocal3.errlocal3.*local3.3 (error)local3.err; local3.crit*.debug

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12. Tip

13. UtilitylogrotateCircular logging, compress and removeSend email using crontabloggerCommand line syslog toollogger -p local0.err 'this message is sent using command line'

14. Remote loggingModify syslogd script on receiverSYSLOGD="${SYSLOGD} -m 0 -r“Modify syslog.conf on senderlocal0.* @your.host.name