Mastering the tail Command in Linux

The tail command in Linux is an invaluable tool for displaying the last part of files, often used for monitoring log files in real time or viewing the end of a large file without needing to open it entirely. When combined with other commands like watch, tail becomes even more powerful, offering dynamic file monitoring capabilities. This article delves into various tail command uses, enriched with examples to enhance your command-line skills.

Basic Usage of tail

To display the last 10 lines of a file:

tail myfile.txt

Customizing the Number of Lines

Specify the number of lines to display using the -n option:

tail -n 5 myfile.txt

Real-time Monitoring with -f

The -f option tails files in real-time, useful for logs:

tail -f /var/log/syslog

tail with watch for Dynamic Monitoring

Combine tail with watch to refresh the displayed output of a file dynamically:

watch tail myfile.txt

Customizing Display and Refresh Interval

Adjust the number of lines and the refresh rate:

watch -n 1 tail -n 10 myfile.txt

This command updates the last 10 lines of myfile.txt every second.

Highlighting Differences

Highlight changes with the -d option:

watch -d tail -n 10 myfile.txt

Combining tail with Other Commands

Using grep for Filtered Monitoring

tail -f /var/log/syslog | grep error

Viewing Multiple Files

tail -n 5 file1.txt file2.txt

Advanced Usage Examples

Display from a Specific Point

tail -n +100 myfile.txt

Following Multiple Files

tail -f file1.log file2.log

Conclusion

The tail command, especially when used in conjunction with watch, offers a flexible and powerful way to monitor files and logs in real-time on Linux systems. Whether you’re tracking log file updates, filtering for specific entries, or monitoring multiple files, mastering tail can significantly enhance your command-line efficiency and productivity.

Created on: May 18, 2024

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