logging
 

I just want to know how logging works internally.

That is much like saying "I just want to know how the world works internally." Would you mind narrowing that down to one or two programming languages, or logging systems? Do you mean syslog, for example, klogd or log4j?

narrowing my question :)
 

i would like to know what exactly happens when we mean that system messages can be seen in /var/log/messages or /var/log/warn(in linux, to be specific)? What happens internally?

Okay, so that would generally be syslog. "man syslog" and "man syslogd" should tell you what you want to know.

In general - most well designed applications - having logging modules that write to specific log files. By doing so, in the event of an error or exception being encountered in your application - all a developer needs to do is look up the log files and he will be able to zero in on the root cause of the issue (and fix it!) within no time.

I hope this is the answer you were looking for.

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