Skip to content What is tail Command?
The tail command in Linux outputs a file’s end content(tail part). This command is very simple to use and is frequently used. E.g tail /var/log/syslog
Prerequisites
Learn the basics of Linux OS
Why do we need a tail command?
- To see the end part of a file.
- To live stream the log of a service through its log file.
tail -f /var/log/nginx/access.log - To find the live pattern for a service by piping its log to grep.
tail -f /var/log/nginx/access.log | grep 500
How to use the tail command in Linux (or Unix)
Syntax – tail option filename
Please go through the man page for details by executing man tail
Frequently used options with tail command
- -f – To see live logs
- -n – To Limit the number of lines in the output
Major Challenges in using the tail command?
Coming up with the correct tail command for the given problem
Let us explore this with an example.
Find the recent log in /var/log/nginx/access.log.
Solution – Recent logs mean – latest log – End logs of /var/log/nginx/access.log
And we know the end content of a file can be viewed using the tail command. So final command is tail /var/log/nginx/access.log
Find the latest 100 lines of log in /var/log/nginx/access.log.
Solution – latest logs mean – End logs of /var/log/nginx/access.log
And we know the end content of a file can be viewed using the tail command.
Next, we need the latest 100 lines -> Use -n 100 -> So the final command is tail -n 100 /var/log/nginx/access.log
Livestream logs of /var/log/nginx/access.log.
Solution – Livestream logs mean – latest log in a flowing manner – End logs of /var/log/nginx/access.log with -f (for live stream)
And we know the end content of a file can be viewed using the tail command. So final command is tail -f /var/log/nginx/access.log
Livestream 100 lines of log in /var/log/nginx/access.log.
Solution – Livestream logs mean – latest log in a flowing manner -> End logs of /var/log/nginx/access.log with -f (for live stream)
And we know the end content of a file can be viewed using the tail command and for live stream -> tail -f
Next, we need to limit to 100 lines -> Use -n 100 -> So the final command is tail -f -n 100 /var/log/nginx/access.log
With the above approach, you can solve any problem related to tail command in Linux.
Do some practice to grasp this command
FAQs on tail command in Linux (Unix)
Q1 – can we use the tail command in macOS as well?
A – Yes, it has the same behavior in macOS as well.
Conclusion
In this post, you learned about the tail command in Linux, its use case, and how to build a tail to see live patterns within a log file.
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