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Editor to share with you how Linux uses the tail command. I hope you will learn a lot after reading this article. Let's discuss it together.

The Linux tail command displays the last portion of one or more files or pipe data (the default is 10 lines); it can be used to monitor file changes in real time.

Linux tail command

The tail command displays the last portion of one or more files or pipe data (the default is 10 lines); it can be used to monitor file changes in real time. One of the most common uses of the tail command is to monitor and analyze logs and other files that change over time, often in conjunction with other tools such as grep.

Basic syntax:

Tail [OPTION]... [FILE]...

OPTION: tail option, let's take a look at some of the most common options.

●-n (--lines) option: specifies the number of rows to display

●-c (--bytes) option: specifies the specific number of bytes to display

●-f (--follow) option: monitor file changes

FILE: zero or more input file names. If FILE is not specified, or if FILE is -, tail reads standard input.

How do I use the tail command?

When using the simplest form without any option, the tail command displays the last 10 lines.

Tail filename.txt

How do I display a specific number of rows?

You can use the-n (--lines) option to specify the number of rows to display:

Tail-n filename.txt

You can also omit the letter n and use only hyphens (-) and numbers (no spaces between them).

To display the last 50 lines of the file named filename.txt, use:

Tail-n 50 filename.txt

The following example shows the same results as the above command:

Tail-50 filename.txt

How do I display a specific number of bytes?

You can use the-c (--bytes) option to display a specific number of bytes:

Tail-c filename.txt

For example, to display the last 500 bytes of data in the file filename.txt, we can use:

Tail-c 500 filename.txt

You can also use a multiplier suffix after a number to specify the number of bytes to display. B times 512 KB times 1000 K times 1024 MB times 1000000 M times 1048576, and so on.

The following command displays the last two kilobytes (2048) of the file filename.txt:

Tail-c 2k filename.txt

How do I view the file to make changes?

To monitor file changes, you need to use the-f (--follow) option:

Tail-f filename.txt

The-f option is particularly useful for monitoring log files. For example, to display the last 10 lines of the / var/log/nginx/error.log file and monitor the file for updates to use:

Tail-f / var/log/nginx/error.log

To break the tail command while monitoring the file, press ctrl+c.

To continue monitoring the file while recreating it, you need to use the-f option:

Tail-F filename.txt

The-f option is useful when the tail command follows a rotated log file. When used with the-f option, the tail command reopens when the file is available again.

How to display multiple files

If more than one file is provided as input to the tail command, it displays the last ten lines of each file.

Tail filename1.txt filename2.txt

Users can use the same options as when displaying a single file.

For example: display the last 20 lines of the files filename1.txt and filename2.txt

Tail-c 20 filename1.txt filename2.txt

How do I use it with other commands?

The tail command can be used in conjunction with other commands, for example, to monitor Apache access log files and display only lines containing the IP address 192.168.42.12, you can use:

Tail-f / var/log/apache2/access.log | grep 192.168.42.12

Or display the first ten running processes sorted by CPU usage:

Ps aux | sort-nk + 3 | tail-5 after reading this article, I believe you have a certain understanding of how Linux uses the tail command. Want to know more about it. Welcome to follow the industry information channel. Thank you for reading!

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