linux log files — Stuff That Spins

Linux Log files and usage

source: http://www.cyberciti.biz/faq/ubuntu-linux-gnome-system-log-viewer/ => /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

To view log files at shell prompt

Use tail, more, less and grep command.

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

View log files using GUI tools using the GNOME System Log Viewer

System Log Viewer is a graphical, menu-driven viewer that you can use to view and monitor your system logs. System Log Viewer comes with a few functions that can help you manage your logs, including a calendar, log monitor and log statistics display. System Log Viewer is useful if you are new to system administration because it provides an easier, more user-friendly display of your logs than a text display of the log file. It is also useful for more experienced administrators, as it contains a calendar to help you locate trends and track problems, as well as a monitor to enable you to continuously monitor crucial logs. You can start System Log Viewer in the following ways: Click on System menu > Choose Administration > System Log:

(The GNOME System Log Viewer) Note you can start the GNOME System Log Viewer from a shell prompt, by entering the following command: $ gnome-system-log &