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Table of contents
1.
Introduction
2.
Usage of the Cat Command
3.
Use Cases of the Cat Command
3.1.
Quick File Viewing
3.2.
File Creation
3.3.
Combining Files
3.4.
Appending Content
3.5.
Scripting & Automation
4.
Examples
4.1.
Displaying File Content
4.2.
Combining Multiple Files
4.3.
Creating a New File
4.4.
Appending to a File
4.5.
Viewing Content with Line Numbers
4.6.
Use Cases of the Cat Command
4.7.
Quick File Viewing
4.8.
File Creation
4.9.
Combining Files
4.10.
Appending Content
4.11.
Scripting & Automation
5.
Options in the Cat Command
5.1.
-n Option
5.2.
-b Option
5.3.
-s Option
5.4.
-E Option
5.5.
-T Option
6.
Linux Cat Command: To Display File Content
7.
Linux Cat Command Usage
7.1.
Viewing Files
7.2.
Creating Files
7.3.
Appending Text
7.4.
Merging Files
7.5.
Viewing with Line Numbers
8.
Frequently Asked Questions
8.1.
Can the cat command edit files?
8.2.
How can I use cat to display multiple files at once?
8.3.
Is it possible to use cat for binary files?
9.
Conclusion
Last Updated: Mar 27, 2024
Easy

Cat Command in Linux

Author Pallavi singh
0 upvote

Introduction

The cat command in Linux is a go-to tool for anyone working with text files. It's simple but packs a punch, letting you view file contents, stitch multiple files together, and even whip up new ones on the fly. 

Cat Command in Linux

This article will walk you through the ins and outs of the cat command, from its basic uses to some handy tricks you might not know yet. After reading this article, you'll be more than ready to handle file-related tasks in Linux with ease.

Usage of the Cat Command

The cat command, short for "concatenate," is mainly used to display the content of text files right on your terminal screen. If you've got a file, say a text document with your notes or a script, and you want to see what's inside without opening a text editor, cat is your friend. It's like turning the pages of a book to read without pulling it off the shelf.

Here's how simple it is to use: if you have a file named notes.txt, you can type cat notes.txt in your Linux terminal, and it will show you all the text that's inside notes.txt on your screen. This is super handy for quickly checking file contents or copying text without opening the file in a full-blown editor.

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Use Cases of the Cat Command

The cat command isn't just for viewing files; it's a versatile tool with several practical uses. Let's explore some of the common situations where cat proves to be incredibly useful:

Quick File Viewing

When you need to peek into a file fast without editing, cat is perfect. It's like flipping a light switch to see what's in a room without stepping in.

File Creation

You can create a simple text file by typing cat > newfile.txt, then writing your content, and ending it with CTRL+D. It's as straightforward as jotting down a note.

Combining Files

If you're looking to merge the contents of several files into one, cat makes it easy. This can be great for compiling logs or reports from multiple sources.

Appending Content

Adding more information to the end of an existing file without opening an editor is another handy use. It's like adding a postscript to a letter already sealed in an envelope.

Scripting & Automation

In scripts, cat is often used to display file content or to feed it into other commands and scripts, making it a building block in automation tasks.

Examples

Displaying File Content

To see what's inside a file called example.txt, you'd use the command:

cat example.txt


This will show all the text from example.txt right in your terminal window.

Combining Multiple Files

If you have two files, first.txt and second.txt, and you want to see their contents one after the other, you can use cat like this:

cat first.txt second.txt


This command will display the contents of first.txt followed by second.txt in your terminal.

Creating a New File

You can also use cat to create a new file. If you want to make a new file named combined.txt that merges the content of first.txt and second.txt, you can do:

cat first.txt second.txt > combined.txt


After running this command, combined.txt will contain the contents of both first.txt and second.txt.

Appending to a File

If you want to add the content of second.txt to the end of first.txt, the command would be:

cat second.txt >> first.txt


This doesn't erase what's in first.txt; it just adds second.txt's content to the end.

Viewing Content with Line Numbers

To make it easier to follow, you can display the contents of a file with line numbers by using cat with the -n option:

cat -n example.txt


This will show every line of example.txt preceded by its line number.

Use Cases of the Cat Command

The cat command isn't just for viewing files; it's a versatile tool with several practical uses. Let's explore some of the common situations where cat proves to be incredibly useful:

Quick File Viewing

When you need to peek into a file fast without editing, cat is perfect. It's like flipping a light switch to see what's in a room without stepping in.

File Creation

You can create a simple text file by typing cat > newfile.txt, then writing your content, and ending it with CTRL+D. It's as straightforward as jotting down a note.

Combining Files

If you're looking to merge the contents of several files into one, cat makes it easy. This can be great for compiling logs or reports from multiple sources.

Appending Content

Adding more information to the end of an existing file without opening an editor is another handy use. It's like adding a postscript to a letter already sealed in an envelope.

Scripting & Automation

In scripts, cat is often used to display file content or to feed it into other commands and scripts, making it a building block in automation tasks.

Options in the Cat Command

While the cat command is widely known for displaying file contents, it comes with several options that enhance its functionality. Here's a look at some useful options that can come in handy:

-n Option

Adds line numbers to the output. This is especially useful when you're working with code or large files and need to refer to specific lines.

cat -n filename.txt

-b Option

Similar to -n, but it only numbers non-blank lines. If your file has empty spaces you don't want numbered, this option is what you need.

cat -b filename.txt

-s Option

Squeezes multiple adjacent blank lines down to a single blank line. This cleans up the view if your file has too much white space.

cat -s filename.txt

-E Option

Displays $ at the end of each line, making it easier to spot line breaks, especially in files where they might affect formatting or execution.

cat -E filename.txt

-T Option

This option will show tabs as ^I, which can be incredibly useful for debugging issues related to indentation or tabulation in files.

cat -T filename.txt

Linux Cat Command: To Display File Content

One of the primary uses of the cat command is to display the contents of a file on your screen. It's straightforward: when you have a text file and you want to see what's inside it without opening an editor, cat does the job quickly and efficiently.

For example, if you have a file named my_notes.txt and you want to read it, simply type:

cat my_notes.txt


This command will show you everything inside my_notes.txt, right there in your terminal. It's like reading a book by simply laying it open on the table, no need to flip through the pages.

This function is particularly useful when working in a command-line environment, where quick access to file contents is often needed without the overhead of opening files in a graphical text editor. Whether you're checking configuration files, reading through logs, or just looking at your own notes, the cat command is a quick and simple way to get the job done.

Linux Cat Command Usage

Getting to grips with the cat command usage involves more than just viewing files. It's a versatile tool that can help you in various tasks, like creating files, merging content, and more. Here's how to use the cat command effectively:

Viewing Files

As mentioned, you can view a file by simply typing cat followed by the file name. It's direct and to the point, perfect for quick checks.

Creating Files

To create a new file, you can use cat in conjunction with redirection. Type cat > newfile.txt, enter your content, and then press CTRL+D to save and exit. Your text is now in newfile.txt.

Appending Text

If you want to add more text to the end of an existing file, cat can do that too. Use cat >> existingfile.txt, type your additional text, and then CTRL+D to append it.

Merging Files

Combining the contents of multiple files into one is another handy use. Type cat file1.txt file2.txt > combined.txt to merge the contents of file1.txt and file2.txt into combined.txt.

Viewing with Line Numbers

If you need to see line numbers for reference or debugging, cat -n yourfile.txt will display the file content along with line numbers at the beginning of each line.

Frequently Asked Questions

Can the cat command edit files?

No, the cat command is primarily used for displaying, combining, and creating files. It doesn't have built-in editing capabilities. For editing, you'd use text editors like nano, vi, or gedit.

How can I use cat to display multiple files at once?

You can display the contents of multiple files sequentially by listing them with spaces in between, like this: cat file1.txt file2.txt. This command will show you the content of file1.txt followed by file2.txt.

Is it possible to use cat for binary files?

While you can use cat on binary files, it's not recommended because binary data can contain control characters that might change terminal settings. For binary files, tools like hexdump or xxd are more suitable for viewing.

Conclusion

In this article, we've learned how the cat command in Linux serves as a versatile tool for various file operations. From displaying file contents in a straightforward manner to combining files and even creating new ones, cat proves to be indispensable for anyone navigating the Linux command line. Its simplicity, coupled with the powerful options it offers, makes cat an essential command to master for efficient file management. By understanding and utilizing the cat command, you'll be better equipped to handle text files and improve your workflow in the Linux environment.

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