Tag Archives: echo mmv cat vi nano free df ps aux ps

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Welcome to another helpful and beginner-friendly blog from hiranmoypati.com! Today, we’re diving into the core of every Linux system – the command line. If you’re learning Kali Linux for ethical hacking, cybersecurity, or even personal exploration, you’ll quickly realize that mastering the terminal is crucial.

In this blog, we’ll walk you through some of the most commonly used and helpful commands in Kali Linux:
echo, cat, mmv, ps, ps aux, vi, nano, free, and df.

Let’s break them down with simple explanations, practical examples, and a friendly tone—so even if you’re a beginner, you’ll feel confident using them in your daily Linux life.

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🔊 1. echo – Display a Line of Text

The echo command is used to display a message or print text to the terminal.

🧪 Example:

echo "Welcome to hiranmoypati.com"

🧠 Output:

Welcome to hiranmoypati.com

You can also use echo to display the value of variables:

name="Hiranmoy"
echo "Hello, $name!"

Output:

Hello, Hiranmoy!

echo is often used in shell scripts to display output or log messages.

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📄 2. cat – View Content of Files

The cat command (short for “concatenate”) allows you to read and display the contents of files.

🧪 Example:

cat file.txt

🧠 Output:

Shows everything inside file.txt.

Want to create a file with cat?

cat > myfile.txt

Now type something and press Ctrl + D to save it.

To append content to an existing file:

cat >> myfile.txt

Great for viewing logs or quick notes!

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🔁 3. mmv – Move/Batch Rename Files

mmv is a powerful tool for batch-renaming and moving files using wildcards. It’s not installed by default, so you’ll need to install it:

sudo apt install mmv

🧪 Example:

mmv "*.txt" "#1.md"

This will rename all .txt files to .md (e.g., notes.txt becomes notes.md).

Another example:

mmv "image_#1.jpg" "photo_#1.jpg"

Super useful for managing a bunch of files at once, especially in scripts.

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🔍 4. ps – Process Status

The ps command shows information about active processes.

🧪 Example:

ps

🧠 Output:

Shows your current shell session processes. To see more detailed process lists, use ps aux (see next section).

This is great for checking what’s running and their process IDs (PIDs), which can be useful for stopping unresponsive tasks.

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🔬 5. ps aux – Detailed View of All Processes

This is an expanded version of ps. It shows all processes running on your system, not just those belonging to the current user.

🧪 Example:

ps aux

🧠 Output:

You’ll see columns like:

• USER: Who started the process
• PID: Process ID
• %CPU and %MEM: Resource usage
• COMMAND: The actual command or program

Need to find a specific process?

ps aux | grep firefox

This filters the results to only show processes with “firefox” in them.

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✍️ 6. vi – The Powerful Text Editor

vi is a classic and lightweight terminal-based text editor. It can be intimidating at first, but it’s extremely powerful once you get the hang of it.

🧪 Opening a File:

vi test.txt

Basic vi commands:

• Press i to enter insert mode
• Type your content
• Press Esc to exit insert mode
• Type :w to save
• Type :q to quit
• Use :wq to save and quit

If you make a mistake:

:q!

Quits without saving.

vi is handy when you’re SSHing into a server and need a quick, lightweight editor.

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🧾 7. nano – The Beginner-Friendly Text Editor

Not a fan of vi? No worries! nano is here.

Nano is simple and comes with on-screen shortcuts. It’s perfect for beginners.

🧪 Example:

nano myfile.txt

Start typing directly. Use the following keys:

• Ctrl + O to save
• Enter to confirm the filename
• Ctrl + X to exit

Super easy and intuitive—great for editing configuration files or scripts.

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🧠 8. free – Show Memory Usage

Want to know how much RAM is available or used? Use free.

🧪 Example:

free -h

🧠 Output:

              total        used        free      shared  buff/cache   available
Mem:           7.6G        2.1G        3.4G        120M        2.1G        5.1G
Swap:          2.0G          0B        2.0G

• -h makes the output human-readable (G for GB, M for MB)
• Helps you track memory leaks or monitor system performance

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💽 9. df – Disk Space Usage

The df command shows how much disk space is used and available on your drives.

🧪 Example:

df -h

🧠 Output:

Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1        50G   18G   30G  40% /

Like free, using -h makes the output easy to understand.

Very useful for checking if your system is running out of space or where space is being used up.

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🧵 BONUS TIP: Combining Commands with Pipes

Linux becomes more powerful when you chain commands using pipes (|) and redirection.

🧪 Example:

ps aux | grep apache

This searches running processes for “apache”. You can combine this with kill to stop a process.

kill -9 PID_NUMBER

Where PID_NUMBER is the number you found using ps aux.

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🧰 Final Words – Practice Makes Perfect

The terminal might look intimidating at first, but it’s a powerful tool. These commands are some of the most useful in day-to-day usage on Kali Linux or any Linux distro.

Command	Use Case
echo	Display text or variables
cat	Read or write file content
mmv	Batch rename or move files
ps	Show current processes
ps aux	Show all system processes
vi	Edit files in a powerful environment
nano	Simple text editing
free	View memory usage
df	Check disk space usage

Learning these commands will make you faster, smarter, and more effective on the command line. So open up your Kali terminal, try them out, and don’t be afraid to explore!

If you’re interested in more Kali Linux tutorials, ethical hacking tips, or productivity hacks—make sure to bookmark hiranmoypati.com, follow us on social media, and subscribe to our newsletter.

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💬 Got a Question?

Drop your doubts or favorite command in the comments below. We love hearing from fellow tech enthusiasts!

Happy Hacking! 🐱‍💻

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