What is the process with an ID of 0 commonly referred to in Linux systems?

The process with an ID of 0 in Linux systems is commonly known as the kernel process. Specifically, this process is often referred to as the idle process or the scheduler process, which is an integral part of the Linux kernel. It is responsible for managing system resources and running the kernel's scheduler, which allocates CPU time to various processes.

In Linux, process IDs (PIDs) are used to uniquely identify processes. The specific assignment of PID 0 to the kernel process signifies its foundational role, as it is the first process that is created when the system boots. This process runs in a privileged mode, allowing it access to hardware resources and the ability to interact closely with the hardware and other system components.

In this context, other terms highlight different types of processes: a child process is one that is created by another process (the parent), a user process is any process started by a user (typically with a non-zero PID), and systemd is an init system used in some Linux distributions but does not equate to the process with PID 0. Understanding these distinctions helps clarify the roles and functionality of various processes within the Linux operating system.