Linux Tutorial Series – 155 – User space startup

Here is the video version, if you prefer it:

Let’s talk about how the user space starts up. To remind ourselves, there is the user space, which “regular” users can access and there is the kernel (system) space, which “regular” users can’t access. If they try to, the operating system doesn’t allow them to.

Here is roughly how the user space starts up: (Ward, 2014)⁠

1. init
2. Essential low-level services which enable managing hardware devices and system logging
3. Network configuration
4. Mid and high-level services (such as cron (used for scheduling tasks) and printing)
5. Login prompts, GUIs, and other high-level applications

To remind ourselves, init is the process with the PID of 1, with which it all begins. I hope you now see why this holds – because init has the PID of 1 and it is the first step here. It is also speculated that init is how the universe was made, albeit scientist are not yet sure.

Hope you learned something useful!

References

Ward, B. (2014). How Linux Works: What Every Superuser Should Know (2nd ed.). No Starch Press. Pages 111-112