In my last post, I gave you a glimpse to runlevels, their purpose, and how they affect the overall operation of your box. Today, in this post, I am going to dig deeper into runlevels, as well as manipulating services in specific runlevels. I’m going to show you why you want to do this, as well as how. We’ll learn about the ‘update-rc.d’ command mainly, spending a great deal of time with examples and demos.
Before I begin, however, I want to make something painfully clear. Linux gives you the awesome power to completely break your box. I’m talking to the point where not even a backup would work, and you’re left with the task of reinstalling the operating system. However, on the flip side, Linux gives you the awesome power to manage and administer your box. Intense flexibility and unbelievable portability. Today, if you’re following along with the examples given in this tutorial, it is possible to leave your box in an unbootable state, or in a state of undesired operation. Of course, this is not what we want. So, if you are going to follow along, I would recommend following along in an Ubuntu virtual machine. Otherwise, take extra care to follow the tutorial exactly, and all should be well.