Linux Administration
Linux Distributions Overview
In this lesson
A Linux distribution (distro) is a complete, ready-to-use operating system assembled from the Linux kernel, a package manager, system utilities, and optional desktop environments or server tools — all bundled together and maintained by an organisation or community. There is no single "Linux OS"; instead, hundreds of distributions exist, each making different choices about what to include, how to configure defaults, and who the target audience is.
What Makes a Distribution
Every Linux distribution is built from the same foundational kernel, but each distro makes its own decisions about the components that sit on top. Think of the kernel as a car engine — the distro decides the bodywork, dashboard, seats, and features around it.
Fig 1 — Every distro stacks its components on top of the same Linux kernel
The tool used to install, update, and remove software. The package manager is one of the biggest differences between distro families.
How often new versions are published. Some distros release on a fixed schedule (LTS), others push updates continuously (rolling release).
Choices about which software comes pre-installed, default shell, security policies, and filesystem layout vary significantly between distros.
Some distros offer paid enterprise support (RHEL, SUSE), some offer community support only (Arch), and some offer both (Ubuntu).
The Two Major Families
The hundreds of Linux distributions mostly descend from two ancestral families: Debian and Red Hat. Knowing which family a distro belongs to tells you immediately which package manager it uses and roughly how it behaves.
Fig 2 — The two main distro family trees
Analogy: Think of distro families like car manufacturers. Toyota and Ford both make cars with the same basic engine principles, but their parts are not interchangeable. Similarly, Debian-family commands and packages don't work on RHEL-family systems — and vice versa.
Popular Distros Compared
Here are the most commonly encountered distributions in professional Linux administration, cloud, and enterprise environments:
LTS vs Rolling Release
One of the most important choices when selecting a distribution is its release model. This affects how stable your system is, how often you get new software, and how much maintenance work is required.
LTS (Long-Term Support)
- Fixed release with a set support window (5–10 years)
- Software versions are frozen and only receive security patches
- Extremely stable — ideal for production servers
- Examples: Ubuntu 22.04 LTS, RHEL 9, Debian 12
Rolling Release
- No fixed versions — software updates continuously
- Always has the latest kernel and packages
- Higher risk of breakage — not ideal for production
- Examples: Arch Linux, openSUSE Tumbleweed
Analogy: LTS is like a long-haul cargo ship — slow, predictable, and reliable. Rolling release is like a speedboat — fast and exciting, but one wrong wave and you're soaked. For servers carrying business-critical workloads, you almost always want the cargo ship.
Choosing the Right Distro
There is no universally "best" distribution. The right choice depends on your use case, your organisation's existing tooling, and certification goals. Use this decision guide:
Ubuntu Server 22.04 LTS — massive community, excellent documentation, identical to many cloud environments. Best starting point for this course.
RHEL 9 or Rocky Linux 9 — industry standard for enterprise, 10-year support, required for RHCSA/RHCE certifications.
Ubuntu or Amazon Linux 2023 — default on most AWS, GCP, and Azure images. Familiar to most cloud engineers.
Arch Linux — forces you to understand every component you install. Excellent for deep learning but not suitable for production servers.
What Stays the Same Across All Distros
Despite their differences, all Linux distributions share a common core. This is great news — skills learned on Ubuntu transfer directly to RHEL, Arch, or any other distro for the vast majority of tasks.
All distros run the Linux kernel. Kernel-level concepts — processes, memory, files, permissions — behave identically everywhere.
Directories like /etc, /var, /home, and /usr are standardised across all distros. You will always find config files in /etc.
Commands like ls, grep, chmod, ps, and ssh work identically on every distro. GNU Coreutils provides this universal foundation.
The Unix permission model — owner, group, others; read, write, execute — is identical across all Linux distributions. Covered in detail in Lesson 6.
Package Manager Mismatch
Never run apt install on a RHEL-based system or dnf install on a Debian-based system — the command simply won't exist. Identifying your distro family before running package management commands is one of the first things to check when connecting to an unfamiliar server. Use cat /etc/os-release to identify any Linux system's distribution immediately.
Lesson Checklist
cat /etc/os-release to identify any Linux distribution
Teacher's Note
For this course, examples use Ubuntu 22.04 LTS and Rocky Linux 9 interchangeably — where commands differ between families, both versions are shown side by side so you're comfortable in any environment.
Practice Questions
1. A colleague connects you to an unfamiliar Linux server. How would you quickly determine which distribution and version it is running?
2. Your company is setting up a new database server that must be supported for 8 years without major OS upgrades. Which distro family and release model would you recommend, and why?
3. Name two things that are identical across all Linux distributions regardless of which distro you use, and explain why this matters for administrators who work across multiple environments.
Lesson Quiz
1. Which package manager is used on Debian-family distributions?
2. What is the key characteristic of a rolling release distribution?
3. Rocky Linux is best described as which of the following?
Up Next
Lesson 3 — Linux File System Structure
Explore the FHS — what lives in /etc, /var, /home, /usr, and every other key directory