What is the method for changing the default runlevel in Linux?

The method for changing the default runlevel in Linux involves editing the /etc/inittab file. The inittab file is a configuration file used by the init system, which is the first process started by the Linux kernel and is responsible for initializing the system and managing its runlevels.

In traditional System V init systems, each runlevel represents a different state of the system, and they are numerically defined (for example, runlevel 3 is typically multi-user mode without a graphical interface, while runlevel 5 includes a graphical interface). By modifying the initdefault line in the /etc/inittab file, one can specify which runlevel the system should enter by default at startup. This is where you can set the desired runlevel.

Although systemctl is a powerful tool used for managing systemd services and targets in later versions of Linux distributions, it doesn't apply to changing the default runlevel as expected in the context of System V init systems. The /etc/runlevels directory does exist in some init systems but does not control default settings for runlevels directly. The init command can change the current runlevel but cannot set the default runlevel upon startup without modifying the relevant configuration files. Therefore, editing the /etc/inittab