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Linux Servers Introduction

Linux is the backbone of modern infrastructure and cloud computing. As a DevOps engineer, mastering Linux is essential for server management, automation, and scalable deployments.

Why Linux for DevOps?

  • Open Source: Cost-effective and customizable
  • Stability: Reliable for production environments
  • Security: Strong permission model and security features
  • Automation: Excellent scripting and automation capabilities
  • Cloud Native: Foundation for containerization and orchestration

Getting Started with Linux

Comprehensive Learning Resource

Free comprehensive course covering Linux fundamentals, perfect for beginners and those needing a refresher.

Essential Linux Concepts for DevOps

File System Hierarchy

/                    # Root directory
├── /bin            # Essential user binaries
├── /boot           # Boot loader files
├── /dev            # Device files
├── /etc            # System configuration
├── /home           # User home directories
├── /lib            # Essential shared libraries
├── /opt            # Optional software packages
├── /proc           # Process information
├── /root           # Root user home
├── /tmp            # Temporary files
├── /usr            # User programs and data
└── /var            # Variable data (logs, databases)

Key Directories for DevOps

DirectoryPurposeDevOps Relevance
/etc/Configuration filesService configuration, system settings
/var/log/System and application logsMonitoring and troubleshooting
/opt/Third-party softwareCustom application installations
/srv/Service dataWeb server content, databases
/home/User directoriesDeveloper workspaces, SSH keys

Essential Linux Skills for DevOps

1. Command Line Proficiency

Master these fundamental commands:

# File operations
ls, cd, pwd, mkdir, rmdir, cp, mv, rm, find, locate

# Text processing  
cat, less, head, tail, grep, sed, awk, sort, uniq, wc

# System information
ps, top, htop, df, du, free, uptime, who, id

# Network
ping, netstat, ss, curl, wget, ssh, scp, rsync

# Process management
kill, killall, nohup, screen, tmux, jobs, fg, bg

# Permissions
chmod, chown, chgrp, umask, sudo, su

2. Package Management

Different distributions use different package managers:

DistributionPackage ManagerCommands
Ubuntu/DebianAPTapt update, apt install, apt remove
RHEL/CentOSYUM/DNFyum install, dnf install, rpm -qa
SUSEZypperzypper install, zypper update
Arch LinuxPacmanpacman -S, pacman -Syu

3. Service Management

Modern Linux uses systemd for service management:

# Service operations
systemctl start service-name
systemctl stop service-name  
systemctl restart service-name
systemctl reload service-name
systemctl enable service-name
systemctl disable service-name

# Service status
systemctl status service-name
systemctl is-active service-name
systemctl is-enabled service-name

# System operations
systemctl reboot
systemctl poweroff
systemctl suspend

Linux Security Fundamentals

User and Group Management

# User operations
useradd username
usermod -aG groupname username
passwd username
userdel username

# Group operations  
groupadd groupname
groupmod groupname
groupdel groupname

# Permission management
chmod 755 filename        # rwxr-xr-x
chmod u+x,g+r filename    # Add execute for user, read for group
chown user:group filename # Change ownership

SSH Security

# Generate SSH key pair
ssh-keygen -t rsa -b 4096 -C "your-email@example.com"

# Copy public key to server
ssh-copy-id user@server

# SSH with key authentication
ssh -i ~/.ssh/private_key user@server

# SSH config file (~/.ssh/config)
Host myserver
    HostName server.example.com
    User myuser
    Port 2222
    IdentityFile ~/.ssh/my_key

Next Learning Steps

After mastering Linux basics, explore:

  1. Network Troubleshooting Tools
  2. Self-Managed Web Hosting
  3. Advanced Hosting Solutions

Practical Exercises

Hands-on Learning

  • Set up a Linux VM or cloud instance
  • Practice command line operations daily
  • Configure SSH key authentication
  • Explore system logs in /var/log/
  • Set up a basic web server

Production Considerations

  • Always test commands in development first
  • Use configuration management tools for consistency
  • Implement proper backup strategies
  • Follow the principle of least privilege
  • Keep systems updated and patched

DevOps Integration

Linux skills directly enable:

  • Infrastructure as Code: Ansible, Terraform automation
  • Containerization: Docker and Kubernetes deployments
  • CI/CD Pipelines: Build agents and deployment scripts
  • Monitoring: Log analysis and system monitoring
  • Cloud Operations: EC2, VPS, and bare metal management