Using Tail Command: View the Final Lines of a File

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In the last blog we understood, how head command makes it simple to read large file by saving time, to detect issue quickly, and efficient troubleshooting. Along with different arguments which allows to display top lines, bytes. Hope it was great.

What is tail in Linux and how do we use it ???

Tail command is used to display last number of lines of a file.

Syntax -

tail [arg] [filname] ........

How to use tail ??

1. When we use tail w/o any arguments, by default it will display last 10 lines from the file.

2. Arguments -

A. -n = It’s used to tell tail to display specific number of lines from the file from the end of the file.

B. -c = It’s used to tell tail to display bytes from the file from the end of the file.

C. -q = It’s used when we want to display data from more than one file together

D. -v = If we want to display the filename as well in the output

Let’s understand it practically

As a system administrator, you're dealing with a situation where the system is under heavy load, and multiple services (web server, database, and application) are logging crucial data. You need to monitor performance issues by analyzing logs from several sources, such as the web server logs, database logs, and system performance logs, all in real-time. You need to aggregate this information into a single view to quickly pinpoint the root cause of the issue.

tail -f /var/log/apache2/access.log | grep "404"

The key advantages of using tail over head in complex, real-world scenarios can be summarized as follows:

• Real-time monitoring and troubleshooting: tail allows you to follow logs as they are written, which is essential for debugging and live troubleshooting.

• Efficient resource usage: When dealing with large files, tail allows you to focus on the most recent data, minimizing memory and I/O usage.

• Log rotation and ongoing monitoring: tail can continue tracking logs even after log files are rotated or renamed.

• Advanced filtering and aggregation: tail integrates well with other tools like grep and awk, enabling complex, real-time filtering and log aggregation across multiple files.

Conclusion -

So, here we understood how tail command makes it simple to read large file by saving time, to detect issue quickly, and efficient troubleshooting. Along with different arguments which allows to display end lines, bytes. Hope it was great.