Since Android is powered by a Linux kernel it should support booting in single-user mode.
Which version of Android supports single-user mode and how is one able to start an Android device in this mode? Any references?
Single user boot is a feature of the init daemon (initd, like sysVinit) and not the Linux kernel. Since Android only shares the kernel with Linux and not the init process, a genuine single user boot can not be achieved.
Android has something that is called "Recovery Mode", but it's not exactly the same as a single user boot on an Unix system. The approach of recovery mode on Android is different because instead of trying to repair the bricked/broken system, on simply can re-flash the ROM or perform a factory reset, which will hopefully restore the systems functionality.
About the init used: Android uses just a script called
IIRC, there is a equivalent of a single mode in Android, when powering up, hold down the menu key, Android boots into 'Safe mode' a lá Windows Safe Mode. This will vary with manufacturers and their Stock ROMs.
As per a brief introduction
Single user mode, also referred to as maintenance mode and runlevel 1, is a way of running Linux or another Unix-like operating system that uses minimal system resources and provides only minimal functionality.
Single user mode can be useful for checking and repairing operating systems, particularly those that have been damaged and will not allow booting (i.e., starting up) into the default GUI (graphical user interface) or console (i.e., text-only) multi-user mode.
To answer your question
With Android, the equivalent of a low runlevel, as to perform critical operations with minimal system resources, is rooting.
From the Wikipedia - Rooting (Android OS):
Since what you are actually seeking is a way to root your device and gain the maximum allowed privileges over it, you can refer to this links: