Linux Administration
Linux is the operating system running under virtually every server, container, and cloud workload. Fluency at the shell is non-negotiable for DevSecOps engineers.
What you’ll learn
Section titled “What you’ll learn”| Topic | Why it matters |
|---|---|
| Essential commands | Navigate, inspect, and manipulate the filesystem from the shell |
| Process management | systemd, ps, top, kill — understand what’s running |
| Networking | ss, ip, curl, dig — diagnose connectivity from the inside |
| File permissions | chmod, chown, ACLs — least-privilege on the filesystem |
| System hardening | Reduce attack surface: disable unused services, configure sshd, run lynis |
| Log analysis | journalctl, /var/log/, structured logs — find what went wrong |
Distributions
Section titled “Distributions”This knowledge base uses Debian/Ubuntu syntax for package management (apt) and RHEL/Rocky (dnf) where they differ. Most concepts apply to any distribution.
Shell assumption
Section titled “Shell assumption”All examples assume:
- Shell:
bash(most common default on servers) - User: non-root with
sudoaccess - Prompt:
$for user,#for root
Where to go next
Section titled “Where to go next”Essential Commands — the 50 commands you’ll use every day