What a Terminal Actually Is: TTYs, PTYs and Job Control
The window is not the terminal, and the terminal is not the shell. What sits between your keystrokes and a program, why Ctrl+C stops one thing and not another, and…
systemd Beyond Services: Units, Targets and Dependencies
systemd manages units, and services are only one kind. Sockets, mounts, targets and slices explained — plus the difference between requiring something and waiting for it, which is behind most…
How Packages and Dependencies Actually Work
What a package contains, how a repository is indexed and trusted, why shared library versions are the real reason dependencies exist, and what mixing sources does to a system.
Containers: What Is Actually Happening
A container is an ordinary Linux process with a restricted view of the system. Namespaces, cgroups and overlay filesystems explained — and the problems that stop being mysterious once you…
What the Kernel Actually Does
Linux is the kernel — not the distribution around it. What lives on each side of the userspace boundary, how to watch a program ask for something, and why an…
What a Shell Actually Is, and Which One to Use
The shell is a program, not the terminal it runs in. Which startup file runs when, why your alias vanishes over SSH, and an honest comparison of bash, zsh and…
SSH Keys: What Is Actually Happening
Key pairs, host keys, the agent and forwarding — what each part does, why the warning about a changed host key matters, and how to hold keys safely.
Filesystems: Inodes, Journalling and Which One to Choose
What an inode is and why you can run out of them, what journalling protects you from, and an honest comparison of ext4, XFS, Btrfs and ZFS.
Linux Networking from First Principles
Addresses, subnets, gateways, ports, DNS and NAT — what each one is for, and a diagnostic order that finds the broken layer in about a minute.
Processes and Memory: What the Numbers Actually Mean
What a process really is, why load average is not CPU percentage, why free -h always looks alarming, and how the OOM killer decides what to kill.