With tail, you can view a Linux log file as the system writes to it in real time. So while you’re trying to troubleshoot that system, you can follow the syslog, the auth.log, faillog, kern.log ...

Jack Wallen walks you through the process of setting up a centralized Linux log server using syslog-ng.

If you really want to see what's happening beneath the hood of your Linux distribution, you need to use log files.