read system log online
 

I'm trying to write a piece of code *if possible* to read system log online. ie. events that occurs at this moment, or of course view log history.

Is there a way to do this using C system calls ?

Are you looking for this command?

tail -f /var/log/messages

I guess that will do

I think you want to look at sys/klog.h

This allows reading from the kernel logs anyway. Check it out to see if it is what you want.

BTW, man klogctl explains it.