k1.2 — What Differs Across Distros (and Why It Matters) 🔎

Even though Linux systems feel similar, the pain points usually come from a handful of predictable differences. Learn these once, and you’ll be able to “translate” smoothly between Debian/Ubuntu and RHEL-like systems (Rocky/Alma). 
 
 1) Package management (how you install/update software) 
 This is the #1 day-to-day difference . 
 
 Debian/Ubuntu: apt (packages are typically .deb ) 
 RHEL family: dnf (packages are typically .rpm ) 
 
 Why you care: 
 
 Commands differ ( apt install vs dnf install ). 
 Package names sometimes differ (e.g., dev headers, utilities, service names). 
 Default repo contents and versions can vary a lot (important for PHP/Node). 
 
 
 2) Release cadence & “stability vs freshness” 
 Distros make different tradeoffs: 
 
 Debian stable / RHEL-like: prioritize predictability and long support windows. 
 Ubuntu LTS: also stable, but often ships newer versions than Debian stable. 
 
 Why you care: 
 
 You might not get the newest PHP/Node from default repos on a “stable” distro. 
 You’ll frequently choose between:
 
 distro packages (stable, integrated), vs 
 vendor repos / language version managers (newer, more moving parts) 
 
 
 
 
 3) Security frameworks & defaults (MAC systems) 
 Two common “why is this blocked?” systems: 
 
 SELinux (very common/enforced on RHEL family) 
 AppArmor (common on Ubuntu) 
 
 Why you care: 
 
 Your config can look correct, permissions can look correct, and it still fails. 
 Troubleshooting often means: 
 service logs + system logs + security policy (not just “chmod it”) 
 
 
 4) Firewall tooling (same concept, different interface) 
 The concept is universal: allow only what you need. 
 But tooling differs: 
 
 Ubuntu commonly: UFW (friendly frontend) 
 RHEL family commonly: firewalld 
 
 Why you care: 
 
 Opening ports (like 80/443) is expressed differently. 
 Guides online often assume one tool; you’ll learn the underlying idea so you can adapt. 
 
 
 5) Defaults, layout conventions, and “where is the config?” 
 Most Linux systems follow similar standards (especially for /etc , /var , logs), but defaults still vary: 
 
 Different default config paths per service 
 Different default module layouts (e.g., Nginx includes, PHP-FPM pool configs) 
 Different service names in systemd 
 
 Why you care: 
 
 You’ll learn to locate configuration and logs reliably, rather than memorize one distro’s exact path. 
 
 
 A useful “translation mindset” ✅ 
 When moving between distros, ask the same questions every time: 
 
 How do I install it here? (APT vs DNF, package names) 
 What’s the service name? ( systemctl status … ) 
 Where are the config + logs? ( /etc/... , /var/log/... , journalctl ) 
 Is a security framework blocking it? (SELinux/AppArmor indicators) 
 
 
 Tiny practice prompt (optional) 
 Tell me which family you want to start with in examples later: 
 
 Debian/Ubuntu 
 RHEL-like (Rocky/Alma) 
 Keep everything dual-written (both), whenever it matters