runlevelit

Runlevel is a feature in Unix-like operating systems that controls the system's behavior when it boots or enters a new runlevel. A runlevel is a number or character that determines the services and processes that are started or stopped. It is commonly used in init systems such as System V and systemd.

The default runlevel is set when the system boots and can be changed later in the boot process. The system's configuration files, such as /etc/inittab and /etc/systemd/system.conf, typically dictate which runlevel is used and what services are started when the system enters that runlevel.

There are various runlevels designated for specific purposes. For example, a multi-user runlevel, such as 3 or 5, typically starts all system services and allows users to log in with a graphical interface. A single-user runlevel, such as 1, starts only essential services, such as the system logger and network configuration. It is then up to the system administrator to manually start or stop other services as needed.

System administrators can switch between runlevels using the telinit command or the systemctl command on systemd-based systems. This can be useful for debugging, maintenance, or recovery purposes. Additionally, many distributions offer pre-defined runlevels for common use cases, such as rescue or emergency modes.

While runlevels have been used in a similar manner, the term "runlevelit" is not a standard syntax and should not be used in practice unless referring specifically to the non-standard or hypothetical term "runlevelit". The primary terms to refer to this concept remain status, runlevels for System V, and levels for systemd.