What I Learned from the Linux Shells Course on TryHackMe

As I continue my journey into cybersecurity and Linux fundamentals, I recently completed the Linux Shells course on TryHackMe. This room gave me a solid understanding of what shells are, how they function, and why they’re a crucial tool in both system administration and ethical hacking.

Here’s a breakdown of what I learned:

🐚 Understanding the Shell

At its core, a shell is a command-line interface that allows users to interact with the Linux operating system. I explored different types of shells, including:

• Bash – the most common shell
• sh – a simpler, older shell
• zsh – more advanced, with added features
• csh/tcsh – shells that use a C-like syntax

Each has its own use cases, and knowing the differences can be key when working in varied environments.

💬 Interactive vs Non-Interactive & Login vs Non-Login Shells

I learned how Linux shells operate differently depending on how they're started:

• Interactive shells are what we typically use in a terminal session.
• Non-interactive shells run scripts or commands in the background.
• Login shells read configuration files like .bash_profile.
• Non-login shells read .bashrc.

This helped me understand why certain environment variables or aliases sometimes don’t load as expected.

🧪 Reverse & Bind Shells

One of the coolest parts of the course was learning how to establish shell connections during exploitation:

• Reverse Shells – where the target connects back to the attacker
• Bind Shells – where the target listens for incoming connections

We used tools like bash, netcat, and socat to set these up—skills that are foundational in penetration testing and CTF challenges.

🔧 Shell Stabilization

After gaining shell access, I learned how to upgrade a limited shell into something more usable. For example:

bash

CopyEdit

python3 -c 'import pty; pty.spawn("/bin/bash")'


This allows for better command-line interaction, such as using arrow keys and tab completion—small upgrades that make a huge difference in post-exploitation.

📜 Scripting Basics

I also dived into basic Bash scripting, including:

• Writing and executing simple scripts
• Using variables, loops, and conditionals
• Making scripts executable with chmod +x

It was a great intro to automation and the logic behind Linux scripting, which is vital for everything from system tasks to building hacking tools.

💡 Final Takeaways

Completing the Linux Shells course really helped me:

• Understand how different shell types behave
• Handle shell access during hacking scenarios
• Start writing basic shell scripts
• Troubleshoot and upgrade limited shell environments

If you’re getting started in Linux or ethical hacking, I highly recommend this course. It’s clear, hands-on, and full of practical insights.