How can the tail -f command be used to monitor log files in real-time?

To monitor log files in real-time, the tail -f command is the perfect tool. Here is how it works and how you can use it:

1. Run the command

In your terminal, type the following and press Enter:

tail -f /home/labex/project/system.log

The terminal will display the last 10 lines of the file and stay open. It is now "following" the file.

2. Witness real-time updates

Unlike a normal command that finishes immediately, tail -f waits for the file to grow. To see this in action:

1. Keep the tail -f terminal open.
2. Open a second terminal tab or window.
3. Run a command to add text to that file, like:

   echo "$(date) [INFO] Real-time test entry" >> /home/labex/project/system.log

4. Look back at your first terminal. You will see the new line appear instantly without you having to re-run any commands!

3. How to stop monitoring

Since the command remains active to keep watching the file, you need to manually stop it when you are finished.

• Press Ctrl + C on your keyboard to terminate the process and return to the command prompt.

Why is this useful?

System administrators use this constantly to watch software logs during a crash or to see if a web server is receiving requests as they happen. It saves you from having to manually open the file over and over again