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Linux tail Command: Display The Ending Content Of The File

In this tutorial, we will explore the tail command in Linux. The tail command is used to display the last part (the tail end) of a file. It is particularly useful for monitoring log files, as it can help you keep track of recent events in real-time.

Basic Usage of the tail Command

The basic syntax for the tail command is as follows:

tail [OPTIONS] [FILE]

By default, the tail command displays the last 10 lines of a file. To display the last 10 lines of a file named example.txt, simply run:

tail example.txt

Displaying a Specific Number of Lines

To display a specific number of lines from the end of a file, use the -n option followed by the number of lines you want to display. For example, to display the last 5 lines of example.txt, run:

tail -n 5 example.txt

Monitoring a File in Real-Time

One of the most powerful features of the tail command is its ability to monitor a file in real-time, displaying new lines as they are added. This is useful for keeping track of log files or other files that are updated frequently.

To monitor a file in real-time, use the -f option, as shown below:

tail -f example.txt

The tail command will keep running, and new lines will be displayed as they are added to the file. To exit the real-time monitoring, press Ctrl+C.

Displaying Multiple Files

The tail command also supports displaying the last part of multiple files at once. Simply provide a list of file names as arguments, like this:

tail file1.txt file2.txt file3.txt

The output will show the last 10 lines of each file, with a header indicating the file name.

Displaying Bytes Instead of Lines

If you want to display a specific number of bytes from the end of a file instead of lines, use the -c option followed by the number of bytes you want to display. For example, to display the last 100 bytes of example.txt, run:

tail -c 100 example.txt

Summary

The tail command in Linux is a powerful tool for displaying the last part of a file. It is especially useful for monitoring log files in real-time. By using various options, such as -n, -f, -c, and more, you can customize the tail command to display the desired number of lines or bytes, monitor multiple files, or follow file updates in real-time.

Displaying the last lines of a file with tail:
- Description: To display the last lines of a file, you can use the tail command followed by the file name.
- Code:
```
# Example: Displaying the last lines of a file
tail filename
```
Following and monitoring log files with tail:
- Description: To follow and monitor log files in real-time, use the -f option with tail.
- Code:
```
# Example: Following and monitoring log file
tail -f /var/log/syslog
```
Customizing output format with tail in Linux:
- Description: The tail command allows customization of the output format, such as showing line numbers or adding headers.
- Code:
```
# Example: Customizing output format
tail -n 10 -v filename
```
Viewing a specific number of lines with tail:
- Description: To view a specific number of lines from the end of a file, use the -n option followed by the desired line count.
- Code:
```
# Example: Viewing a specific number of lines
tail -n 20 filename
```
Using tail for real-time file updates in Linux:
- Description: The -f option in tail allows continuous monitoring and displays updates in real-time as new lines are added to a file.
- Code:
```
# Example: Real-time updates with tail
tail -f /var/log/nginx/access.log
```
Scrolling through large files with tail:
- Description: To scroll through large files, use the -n option to set the number of lines to display.
- Code:
```
# Example: Scrolling through a large file
tail -n 50 largefile.log
```
tail command examples for different scenarios:
- Description: tail can be used in various scenarios, such as checking log files, monitoring ongoing processes, or viewing recent changes in files.
- Code:
```
# Example: Using tail for different scenarios
tail -f /var/log/auth.log
```
Troubleshooting common issues with tail in Linux:
- Description: Common issues with tail may involve incorrect file paths, permission errors, or issues with the -f option not displaying updates.
- Code:
```
# Example: Troubleshooting with tail
tail -n 10 /path/to/nonexistent/file
```