How to Use Cat Command in Linux? [Explained with Examples]

Introduction

The cat command stands as a robust tool in Linux, empowering users to effortlessly create, view, and concatenate files. It holds a pivotal role in the toolkit of any Linux user, offering a pathway to heightened productivity. You can also learn about Linux file systems here. This blog delves into the multifaceted use cases of the cat command, providing clear examples to facilitate a profound understanding of its effective utilization.

What is Cat Command?

Basic Syntax

cat [options] [file(s)]

• cat: The command name.
• [options]: Optional flags to modify the command’s behavior (see below).
• [file(s)]: One or more file names to read. If no files are specified, cat reads from standard input (usually the keyboard).

Common Options

• -n: Numbers each line of output.
• -b: Numbers only non-blank lines.
• -s: Squeezes consecutive blank lines into a single newline.
• -v: Displays non-printing characters (e.g., tabs, newlines) as visible symbols.
• -E: Displays a dollar sign ($) at the end of each line.
• -T: Displays tab characters as ^I.

Practical Implementation

1. Viewing File Contents

Quickly display the contents of a text file:

cat my_file.txt

2. Creating New Files

Create a new file and input text directly:

cat > new_file.txt

(Type text, then press Ctrl+D to save and exit.)

3. Combining Files

Concatenate multiple files into a single file:

cat file1.txt file2.txt file3.txt > combined_file.txt

4. Appending to Files

Add content to the end of an existing file:

cat new_content.txt >> existing_file.txt

5. Numbering Lines

Display a file’s content with numbered lines:

cat -n code.py

6. Viewing Non-Printing Characters

Reveal hidden characters like tabs and newlines

cat -v configuration.txt

7. Piping to Other Commands

Send file contents to other commands for further processing:

cat log_file.txt | grep "error"

8. Creating Temporary Files

Generate a quick temporary file for testing or scripts:

cat > temp_file.txt << EOF

>This is some temporary content.

>EOF

9. Viewing System Information

Read from system devices or files representing hardware:

cat /proc/cpuinfo  # View CPU information

cat /dev/random   # Generate random data

Conclusion

This blog has meticulously navigated through the diverse applications of the cat command in Linux. From viewing file contents to concatenating files and creating new ones, the versatility of the cat command has been unveiled. By mastering this command, Linux users can significantly enhance their productivity, making it an indispensable asset in their toolkit.

Key Takeaways

• The cat command serves as a versatile tool for viewing, concatenating, and creating files in Linux.
• Utilize cat to effortlessly display file contents in the terminal.
• Leverage the command for concatenating the contents of multiple files into a single, cohesive file.

Frequently Asked Questions