Linux Log files and usage
=> /var/log/messages : General log messages => /var/log/boot : System boot log => /var/log/debug : Debugging log messages => /var/log/auth.log : User login and authentication logs => /var/log/daemon.log : Running services such as squid, ntpd and others log message to this file => /var/log/dmesg : Linux kernel ring buffer log => /var/log/dpkg.log : All binary package log includes package installation and other information => /var/log/faillog : User failed login log file => /var/log/kern.log : Kernel log file => /var/log/lpr.log : Printer log file => /var/log/mail.* : All mail server message log files => /var/log/mysql.* : MySQL server log file => /var/log/user.log : All userlevel logs => /var/log/xorg.0.log : X.org log file => /var/log/apache2/* : Apache web server log files directory => /var/log/lighttpd/* : Lighttpd web server log files directory => /var/log/fsck/* : fsck command log => /var/log/apport.log : Application crash report / log file
src - https://ubuntuforums.org/showthread.php?t=1568706&p=9810348#post9810348
origin - http://www.pipiscrew.com/?p=6552 linux-event-log