Operating Systems: Windows, macOS, and Linux

Every device a technician supports runs an operating system. Even if a workplace is "all Windows", you'll encounter Mac laptops, Linux servers, and the Android/iOS phones in everyone's pocket. This lesson establishes the shared mental model and points out where each OS diverges.

What an Operating System Does

Five fundamental responsibilities:

1. Process management: Start, stop, schedule programs across CPU cores
2. Memory management: Allocate and protect RAM between processes
3. File system: Organise data on storage devices
4. Device management: Drivers that talk to printers, GPUs, NICs, USB devices
5. User interface: GUI shell + command shell for humans to interact with the system

The Three Desktop Families

Windows Essentials

Editions

• Home: Consumer; no domain join
• Pro: Adds domain join, BitLocker, Group Policy, Remote Desktop host
• Enterprise: Adds advanced security, app management features; volume licensed
• Education: Enterprise feature set for schools

Core tools

• Task Manager (Ctrl+Shift+Esc): Running processes, CPU/RAM, startup apps
• Settings: Modern config UI
• Control Panel: Legacy config — still needed for printer queues, device management
• Event Viewer: System / Application / Security logs
• Services (services.msc): Background daemons; start/stop/automatic
• Disk Management (diskmgmt.msc): Partition / format drives
• Registry Editor (regedit): Hierarchical config database
• Device Manager: Driver issues, unknown devices
• PowerShell: The default scripting and administration shell

Useful command-line

ipconfig /all              # network adapters
ping 8.8.8.8                # connectivity test
sfc /scannow                # scan and repair system files
chkdsk C: /f                # check and repair disk
gpupdate /force             # refresh group policy
winget install <app>       # install software
Get-Process                 # list processes
Get-Service                 # list services

macOS Essentials

• Built on a Unix foundation — POSIX tools available out of the box
• System Settings replaces System Preferences (macOS 13+)
• Activity Monitor = Task Manager equivalent
• Finder = file explorer; Cmd+Shift+. shows hidden files
• Time Machine for backups; iCloud for sync
• Spotlight (Cmd+Space) is the fastest app launcher and search
• Disk Utility for partitioning and APFS volume management
• Terminal: zsh by default — most Linux commands work

Useful commands

ifconfig                          # network adapters (or 'ip a' on Linux)
diskutil list                     # storage devices
softwareupdate --install --all    # install all available updates
brew install <package>            # install via Homebrew
killall Finder                    # restart Finder
caffeinate                        # prevent sleep

Linux Essentials

Linux isn't one OS but many distributions sharing a kernel. The ones a technician sees:

• Ubuntu / Debian: apt package manager; common on desktops and cloud VMs
• Red Hat Enterprise Linux (RHEL) / Rocky / AlmaLinux / Fedora: dnf package manager; enterprise servers
• SUSE Linux Enterprise Server (SLES): zypper; common in European enterprises
• Arch / Manjaro: pacman; rolling release; power users

Universal Linux command line

ls -la                  # list files with details
cd /etc                 # change directory
pwd                     # current directory
cat /etc/os-release     # OS info
ps aux                  # processes
top / htop              # live process viewer
df -h                   # disk usage
free -h                 # memory usage
ip a                    # network interfaces
systemctl status sshd   # check a service
sudo apt update && sudo apt upgrade   # update (Debian/Ubuntu)
sudo dnf update                       # update (RHEL/Fedora)
journalctl -u nginx     # service logs

Universal Concepts (Named Differently)

File System Layouts

Windows

C:\Windows\         OS files
C:\Program Files\   64-bit apps
C:\Program Files (x86)\   32-bit apps
C:\Users\<name>\   user profile
C:\ProgramData\     shared app data (hidden)

macOS / Linux

/             root
/Users (mac) or /home (Linux)   user homes
/etc          system config files
/var          variable data (logs, databases)
/usr          user programs
/tmp          temp files
/Applications (mac)             apps

Installation Basics

1. Create installation media (USB drive — Rufus on Windows, Disk Utility/Etcher on Mac/Linux)
2. Configure UEFI: boot from USB; disable Secure Boot if installing some Linux distros
3. Partition: typically wipe and install OS-managed scheme; modern OSes use GPT
4. Choose user account type — administrator vs standard
5. Apply updates immediately — first patch cycle closes known vulnerabilities

Updates and Patching

• Windows Update is mandatory for most consumer/business; defer feature updates with policies in enterprise
• macOS updates via System Settings > General > Software Update
• Linux: apt / dnf update commands, often via automation (unattended-upgrades)
• For business: use WSUS / Intune (Windows), Jamf / Kandji (Mac), Ansible / Satellite (Linux) for centralised patching

Choosing Among Them

For end-user laptops in most businesses: Windows for Office/legacy compatibility, Mac for creative and many tech roles. For servers and cloud workloads: Linux dominates — over 95% of public cloud VMs and effectively all containers. As a technician you'll touch all three; depth in one + literacy in the others is the sweet spot.