Linux Fundamentals for DevOps Engineers

Lesson 1 of 26 · Module: Linux

12 min read · Source notes — 70 Linux Commands You Need to Know

Linux is the bedrock of modern DevOps, cloud infrastructure, containerization (Docker, Kubernetes), and server administration. Every container runs a Linux userland; every cloud VM boots Linux by default.

The Linux Architecture: Kernel vs Shell

Hardware (CPU, RAM, Disks, Network Interfaces)
   ↓
Linux Kernel (Process Scheduler, Memory Manager, Virtual File System, Network Stack)
   ↓
Shell & Utilities (Bash, Zsh, Systemd, Coreutils, Package Managers)
   ↓
User Applications & Containers (Docker, Nginx, Node.js, Python, PostgreSQL)

Linux Filesystem Hierarchy Standard (FHS)

Unlike Windows (which uses drive letters like C:\), Linux uses a single unified tree starting at the root directory /.

Instructor introducing the terminal environment and core workflow for essential Linux administration.

Standard Streams & Redirection

Every Linux process starts with three default input/output streams:

• 0 (stdin): Standard Input (keyboard by default)
• 1 (stdout): Standard Output (terminal display)
• 2 (stderr): Standard Error (terminal display for errors)

Example: Redirecting stdout and stderr in DevOps

# Redirect stdout to a file (overwrite)
echo "Deploying version 2.4.0" > deploy.log

# Append stdout to a file
echo "Migration completed successfully" >> deploy.log

# Redirect stderr to an error log
./run_app.sh 2> errors.log

# Redirect BOTH stdout and stderr to the same file (industry standard for cron/systemd)
./start_worker.sh > output.log 2>&1
# Or in modern Bash:
./start_worker.sh &> output.log

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