General system logs (commonly used logs)
/var/log/message – General message- and system-related info
/var/log/cron.log – Cron job logs
/var/log/maillog – Mail server logs
/var/log/kern.log – Kernel logs
/var/log/httpd/ – Apache access and error logs
/var/log/boot.log – System boot logs
/var/log/mysqld.log – MySQL database server logs
/var/log/secure – SSH authentication logs
/var/log/auth.log – Authentication logs
/var/log/qmail/ – Qmail log directory (more files inside this directory)
/var/log/utmp or /var/log/wtmp – Login records file
/var/log/yum.log – Yum log files