If you are like me and often forget what Log files records what, and the commands to easily interrogate them, then hopefully this post will shed some light.

Name and Usage
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 log message to this file
• /var/log/dmesg : Linux kernel ring buffer log
• /var/log/dpkg.log : 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/fsck/* : fsck command log
• /var/log/apport.log : Application crash report / log file

To analyse Log file the following commands will be useful


tail -f /var/log/apport.log
more /var/log/xorg.0.log
cat /var/log/mysql.err
less /var/log/messages
grep -i fail /var/log/boot