Blog 3: Learning Linux – The Language of DevSecOps

Written & Patented by Kalyan Kalavena

This blog is protected by author rights. No copying or editing allowed.

If you're serious about a DevSecOps career, Linux is your first language. It runs the servers, powers automation, handles scripts, and is the heart of cloud computing.

In this session, I started talking to servers using just the terminal — no mouse, no windows, just pure commands and logic.

🔹 Why Linux is So Important

Area	Linux Role
Cloud	Most servers use Linux
Security	File permissions, user rules
Automation	Bash, Cron, Logs
Performance	Lightweight, fast

📂 File & Folder Navigation

pwd – Show current path
ls – List files
cd folder – Move into folder
cd .. – Go up one level
mkdir myfolder – Create folder
touch file.txt – Create file
rm file.txt – Delete file

👨‍💻 Example

mkdir projects
cd projects
touch notes.txt
ls

Output: notes.txt – You created and listed a file!

⚙️ View & Edit Files

cat file – View contents
vi file – VIM editor
nano file – Simple editor

🧠 Combine Commands

mkdir logs && cd logs && touch app.log

Creates folder, goes inside, and makes a file – in one shot.

🔐 Access Levels

$ – Normal user
# – Admin (root)
sudo su – Switch to root
sudo su - – Root + root folder

📂 File Listings

ls -l – Long format
ls -lt – New files top
ls -ltr – Old files top
ls -la – All files

🌐 Downloading Files

wget URL – Download file
curl URL – View content
curl URL -o file – Save file

🔎 Filtering & Piping

grep word file – Search inside
cut -d "/" -f9 – Extract field
awk -F ":" '{print $1}' – Usernames
find / -name "file" – Search file

🔐 Connect to Server (EC2)

Generate public/private key
Import key in AWS
Set up firewall
Launch EC2
Connect via:
```
ssh -i your-key.pem ec2-user@your-ip
```
Terminate when done

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Blog 3: Mastering Linux Fundamentals – The Backbone of DevSecOps