The tail command stands for “tail of the file,” and as the establish suggests, it’s necessarily used to view the general part of files. Whether or not or now not you’re monitoring log files or tracking real-time knowledge changes, tail is your go-to software.

The command is frequently used along side other Linux directions like grep for taking a look, awk for text processing, and | (pipe) for chaining a couple of directions together. As an example, likelihood is that you’ll use tail -f /var/log/syslog | grep "error" to watch device logs for errors in real-time.

Customary syntax for tail command:

$ tail [OPTION...] [FILE...]

1. Display the fitting collection of lines

tail -n [number] [file]

Using this option signifies that you’ll be able to get the tail command to supply output that may display a certain collection of lines in a file.

Example:

Suppose you’ve gotten a text file named example.txt with the following content material subject material:

Line 1: That's the number one line.
Line 2: This is the second line.
Line 3: That's the third line.
Line 4: That's the fourth line.
Line 5: That's the fifth line.
Line 6: That's the sixth line.
Line 7: That's the seventh line.
Line 8: That's the eighth line.
Line 9: That's the ninth line.
Line 10: That's the tenth line.

If you want to display the general 3 lines of this file, you might be able to use the following command:

tail -n 3 example.txt

This will show you the general 3 lines of the example.txt file.

Line 8: That's the eighth line.
Line 9: That's the ninth line.
Line 10: That's the tenth line.

2. Display lines starting from a decided on line amount

tail +[number] [file]

The command with the + sign outputs knowledge starting from the required line amount.

Example:

Let’s say you’ve gotten a text file named example.txt with the following content material subject material:

Line 1: That's the number one line.
Line 2: This is the second line.
Line 3: That's the third line.
Line 4: That's the fourth line.
Line 5: That's the fifth line.
Line 6: That's the sixth line.
Line 7: That's the seventh line.
Line 8: That's the eighth line.
Line 9: That's the ninth line.
Line 10: That's the tenth line.

If you want to display the content material subject material starting from line 5 to the highest of the file, you’ll use the following command:

tail +5 example.txt

The output may well be:

Line 5: That's the fifth line.
Line 6: That's the sixth line.
Line 7: That's the seventh line.
Line 8: That's the eighth line.
Line 9: That's the ninth line.
Line 10: That's the tenth line.

3. Display a couple of files

tail [file1] [file2]

Use this command to turn the ideas of a couple of files at the identical time.

Example 1: Viewing the Ultimate 10 Traces of a Single Record

Let’s say you’ve gotten a file named example.txt with the following content material subject material:

Line 1: Hello
Line 2: World
Line 3: This
Line 4: is
Line 5: a
Line 6: development
Line 7: text
Line 8: file
Line 9: for
Line 10: demonstration
Line 11: purposes
Line 12: very best

Running the command:

tail example.txt

Will output:

Line 3: This
Line 4: is
Line 5: a
Line 6: development
Line 7: text
Line 8: file
Line 9: for
Line 10: demonstration
Line 11: purposes
Line 12: very best

Example 2: Viewing the Ultimate 10 Traces of Multiple Information

Suppose you’ve gotten every other file named example2.txt with the following content material subject material:

Line 1: Each and every different
Line 2: Example
Line 3: Record

You’ll have the ability to view the general 10 lines of every example.txt and example2.txt via running:

tail example.txt example2.txt

This will output:

==> example.txt  example2.txt <==
Line 1: Each and every different
Line 2: Example
Line 3: Record

The ==> <== notation is used to separate the output from different files.

4. Output a certain collection of bytes

tail -c [bytes] [file]

To turn a decided on collection of bytes in a text file, use the -c risk.

Example:

Let’s consider now we have a file named development.txt with the following content material subject material:

That's the number one line.
This is the second line.
That's the third line.
That's the fourth line.
That's the fifth line.

If we wish to display the general 20 bytes of this file, we may use the following command:

tail -c 20 development.txt

5. Use a couple of directions at once

tail [file] | [other_command]

Use the tail command with pipes | to use it along side every other command.

Example: Using tail with grep

Let’s consider you’ve gotten gotten a log file referred to as server.log and you wish to have to check the general 10 lines for any occurrences of the word “error“.

tail server.log | grep 'error'

Here’s what happens:

• tail server.log reads the general 10 lines of the server.log file.
• The output is then piped (|) to the grep 'error' command.
• grep 'error' filters the lines to only show those that contain the word “error“.

6. Follow files in real-time

tail -f [file]

The -f risk is used to track file changes. When new log entries are added to the log file, it updates the display inside the terminal window.

Example:

Let’s consider you’ve gotten gotten a log file named application.log that is being written to while an application is operating. You need to watch this log file for any new entries.

Open a Terminal Window, navigate to the checklist where application.log is situated, i.e cd /path/to/checklist.

Run the tail -f command:

tail -f application.log

After running this command, you’ll be able to see the general 10 lines of application.log displayed inside the terminal. The terminal will stay open, and any new lines added to application.log may well be displayed in real-time.

Additional Linux directions:

The post Tips on how to Use the Tail Command in Linux appeared first on Hongkiat.

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