One of the most crucial pieces of any UNIX-like operating system is the init dæmon process. In Linux, this process is started by the kernel, and it's the first userspace process to spawn and the last one to die during shutdown.

Lightweight virtual containers with PID 1. In this article, I demonstrate a method to build one Linux system within another using the latest utilities within the systemd suite of management tools. The guest OS container design focuses upon BusyBox and Dropbear for the userspace system utilities, but I also work through methods for running more general application software so the containers are actually useful.