Terminology

This section describes the terminology used in shutting down and booting a system.

• Run levels and init states - A run level is a software configuration of processes and available services that describes how a system is shut down or booted. Run levels are also referred to as init states because the init process starts and stops the system processes that are available at each run level. This book refers to init states as run levels.

• Boot Types - A boot type describes how a system is booted, which may include a shutdown of the operating system as well. Different boot types include:

  • Interactive boot - You are prompted to provide information about how the system is booted, such as the kernel and device path name.

  • Reconfiguration boot - The system is reconfigured to support newly added hardware or new pseudo devices.

  • Recovery boot - The system is hung or an invalid entry is prohibiting the system from booting successfully or from allowing users to log in.