Blog 4: Linux Command Mastery – DevSecOps Made Easy

🔐 Blog 4: Linux Command Mastery – Your First Real Step into DevSecOps

By Kalyan Kalavena – Learn Linux like you’re talking to a machine, not fighting one.

🚀 Why Linux is Essential in DevSecOps

If you're serious about DevSecOps, the first skill you must master is Linux. It powers cloud servers, automation scripts, and production environments across the world.

• Cloud Servers: Most use Linux OS (e.g., Ubuntu, Amazon Linux)
• Security: File permissions, SSH access, user control
• Automation: Bash scripts, cron jobs, logs
• Speed: Lightweight, resource-efficient

📂 Getting Started – File & Folder Navigation

pwd               # Show current directory
ls                # List files
cd foldername     # Enter folder
cd ..             # Go back one level
mkdir myfolder    # Create new folder
touch file.txt    # Create an empty file
rm file.txt       # Delete file (carefully!)

👨‍💻 Simple Use Case

mkdir projects
cd projects
touch notes.txt
ls
# Output: notes.txt

📝 Viewing and Editing Files

cat filename       # See file contents
vi filename        # VIM editor
nano filename      # Simpler editor

⚙️ Combo Command Tip

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

This creates a folder, enters it, and creates a file in one go!

🔑 SSH Access & File Permissions

ssh -i <private-key-path> ec2-user@<IP>

Use the command above to securely access your AWS EC2 instance using your private key.

Path Explanation:

• Absolute: /c/devops/daws-82s/daws-82s.pem
• Relative: daws-82s/daws-82s.pem

📌 Important Commands Cheat Sheet

ls -l       # Detailed view
ls -lt      # Sort by latest
ls -ltr     # Oldest files last
ls -la      # Show hidden files

cat > file.txt    # Write text, save with Ctrl+D
>>                # Append to file
mkdir folder      # Create directory
rm -r folder      # Delete directory recursively

🔍 Searching and Filtering

grep "keyword" filename
cat filename | grep "keyword"

# Cut Example
cut -d "/" -f9

# AWK Examples
awk -F ":" '{print $1}' /etc/passwd

🧠 What I Learned in Session 02

• Linux gives control and clarity
• Every command has purpose
• You can control machines without a mouse!

🛡️ This content is protected under patent by Kalyan Kalavena. Reuse or modification is strictly prohibited without permission.