RH124 Ch 1: Getting Started with RHEL

Red Hat Enterprise Linux (RHEL) is a commercially supported Linux distribution built from open-source projects. Fedora is where new ideas are tried first, CentOS Stream is the preview of the next RHEL minor release, and RHEL is the stable, long-supported product. RHEL 10 is the version the current RHCSA exam (EX200) uses.

What makes up a Linux system - The kernel talks to the hardware and runs processes. - The shell (bash on RHEL) reads your commands. - Packages (RPMs) deliver everything else, installed with dnf.

First commands on a new server - cat /etc/redhat-release (or /etc/os-release) — which release is this? - uname -r — which kernel is running? - hostname — which machine am I on? - whoami, id — who am I and which groups am I in? - ssh student@serverb — log in to another machine; exit returns.

Users: root is the all-powerful administrator. Day-to-day you work as a normal user and use sudo for admin tasks. The prompt ends in $ for normal users and for root.

Exam habits from day one - Read every task twice; the exam marks end results, not the commands you typed. - Work on the right machine — check hostname before you start a task. - Make changes persistent: if it would not survive a reboot, it does not count.