CentOS Quick Start Guide

Monitoring live log file traffic using the tail command

While performing troubleshooting, it is required to view the logs being generated by an application when it is being run. Using the tail command with the -f option does this. In one Terminal, we will execute the application we want to troubleshoot, and in another Terminal, we will execute the tail command as shown in the following:

# tail -f </path_of_log_file>

It displays the 10 lines from the bottom of the filename specified, and keeps the file open to view the new lines that are being written to it. Once we are done viewing logs, we can close the log file by pressing Ctrl + C.

For example, to monitor the failed login attempts on the system, on one Terminal, open /var/log/secure, and ...