1. Introduction
Tail is a command-line utility in Linux that is used to display the last few lines of a file. It is often used to monitor log files in real-time and track changes as they happen. In this article, we will learn how to use the tail command effectively and explore some of its useful options.
2. Basic Usage
The basic usage of the tail command is as follows:
tail [options] [file]
By default, tail displays the last 10 lines of a file. For example, if we have a file named "example.txt" and we want to see the last 10 lines, we can use the following command:
tail example.txt
It will display the last 10 lines of the file "example.txt".
3. Specifying the Number of Lines
We can specify the number of lines to display using the "-n" option. For example, let's say we want to display the last 5 lines of a file, we can use the following command:
tail -n 5 example.txt
This will display the last 5 lines of the file "example.txt".
4. Following a File
The "-f" option is used to follow a file and display new lines as they are added to the file. This is useful when we want to monitor log files in real-time. For example, if we want to follow the log file "logfile.txt", we can use the following command:
tail -f logfile.txt
Now, tail will continuously monitor the file "logfile.txt" and display any new lines that are added to it.
5. Displaying Lines in Reverse Order
The "-r" option is used to display lines in reverse order. This can be useful when we want to see the first few lines of a file instead of the last few lines. For example, if we want to display the first 5 lines of a file in reverse order, we can use the following command:
tail -r -n 5 example.txt
This will display the first 5 lines of the file "example.txt" in reverse order.
6. Continuous Output with Delay
The "-s" option is used to specify a delay between displaying each line. This can be useful when we want to see the output of tail at a slower pace. For example, if we want to display the last 10 lines of a file with a delay of 2 seconds between each line, we can use the following command:
tail -s 2 example.txt
This will display the last 10 lines of the file "example.txt" with a delay of 2 seconds between each line.
7. Displaying Bytes
The "-c" option is used to display a specified number of bytes instead of lines. For example, if we want to display the last 100 bytes of a file, we can use the following command:
tail -c 100 example.txt
This will display the last 100 bytes of the file "example.txt".
8. Conclusion
In this article, we have learned how to use the tail command in Linux. We explored some of its useful options such as specifying the number of lines, following a file, displaying lines in reverse order, continuous output with delay, and displaying bytes. The tail command is a powerful tool for monitoring log files and tracking changes in real-time. It is a command that every Linux user should be familiar with.