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.
How Linux Boots, and Where It Goes Wrong
Firmware to bootloader to kernel to systemd, in order — what each stage does, how to tell which one failed, and how to recover from each.
The Linux Filesystem: What Every Directory Is For
A tour of the top-level directories on a Linux system — what belongs in each, why /usr and /var are split, and where to look for the file you are…
Users, Groups and Root: How Linux Decides Who Can Do What
UIDs and GIDs, why most accounts on your system are not people, what root actually is, and the group memberships that quietly hand out administrative power.