What is the difference between messages and logs?

I seen in Unix when an error occur ...

we will  look into logs  or messages .

What are the difference between these two ?
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gheistConnect With a Mentor Commented:
"/var/log/messages" is very basic log file, commonly accessible by all system users. Maybe that is a reference to "syslog" program that does base logging of system events (like apache unable to write its logfile)
Some applications do write their own logs in their formats.
arnoldConnect With a Mentor Commented:
It is a matter of configuration and the applicaiton.

The messages is usually handled through syslog.  I.e. an application encounters an error it sends a notice to the syslog.  Based on the configuration of the syslogd.conf file the error is recorded in messages and/or someplace else.
A log file of an application could be directly accessed by the application. i.e. the application has an error, it appends the error into the log file.

Hope this clears things up.
jaisonshereenAuthor Commented:
So both are used for application ..what is the difference here ..can give a real example?
arnoldConnect With a Mentor Commented:
The difference is how the data gets into the file.
i.e. syslog (system event logger)
Apache maintains their own log files. access,error, etc.  The apache process directly inserts entries into those.

When a kernel process can not access a device/disk it sends an error message to syslog.  Syslog based on its configuration logs the error in /var/log/messages or another file defined within the /etc/syslogd.conf.
The difference is that the kernel process does not directly access a log file to write the error.  If syslog is not running, the error is not recorded.

In simpler terms, the difference is whether you write the error in the error log or you tell someone that there was an error and that person records the error in an error log.
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