The kernel primitives, init systems, and tooling behind the world's most-deployed OS.
Released December 17, 2003, the 2.6 series brought in-kernel preemption, NPTL threading, SELinux, and support for far larger process/user counts — the foundation the kernel built the next two decades on.
A minimal but complete walkthrough of writing, building, loading, and communicating with a Linux kernel module.
How procfs and sysfs expose live kernel state as ordinary files, and the specific paths worth knowing for debugging a running system.
How Debian's APT, Fedora's DNF, and Arch's Pacman differ in dependency resolution, package format, and update philosophy.
How eBPF lets sandboxed, verified programs run inside the kernel, and why that changed what's possible for tracing, networking, and security tooling.
How the VFS layer lets ext4, XFS, Btrfs, NFS, and procfs all answer to the same read/write/open calls.
A stage-by-stage tour from power-on firmware through GRUB, the kernel, initramfs, and systemd reaching a running system.
How cgroup v2's unified hierarchy replaces v1's tangled controller mounts, and how to read and write limits directly through the filesystem.
How each of the Linux kernel's namespace types isolates a specific global resource, and why containers are just processes with a curated set of them.
How systemd's unit model replaced sequential init scripts with declarative, dependency-driven service management.