How to check Runlevel of our Linux system

We will discuss two easy ways to check runlevel in our linux system.

1) Using `runlevel` command

runlevel

This command will show what runlevel we are.

2) Using `who` command

who -r

By default, most of the LINUX-based system boots to runlevel 3 or runlevel 5. In addition to the standard runlevels, users can modify the preset runlevels or even create new ones according to the requirement. Runlevels 2 and 4 are used for user-defined runlevels and runlevel 0 and 6 are used for halting and rebooting the system. Obviously, the start scripts for each run level will be different performing different tasks. These start scripts corresponding to each run level can be found in special files present under rc subdirectories. At /etc/rc.d directory there will be either a set of files named rc.0, rc.1, rc.2, rc.3, rc.4, rc.5, and rc.6, or a set of directories named rc0.d, rc1.d, rc2.d, rc3.d, rc4.d, rc5.d, and rc6.d. For example, run level 1 will have its start script either in file /etc/rc.d/rc.1 or any files in the directory /etc/rc.d/rc1.d.

A run level is a state of init and the whole system defines what system services are operating. Run levels are identified by numbers. Runlevel is a mode or state in which a Linux system operates. It has a crucial role in the management of the Linux System.

• Whenever a LINUX system boot, firstly the init process is started which is actually responsible for running other start scripts which mainly involves initialization of your hardware, bringing up the network, and starting the graphical interface.
• Now, the init first finds the default runlevel of the system so that it can run the start scripts corresponding to the default run level.
• A runlevel can simply be thought of as the state your system enters like if a system is in a single-user mode it will have a runlevel 1 while if the system is in a multi-user mode, it will have a runlevel 5.
• A runlevel, in other words, can be defined as a preset single-digit integer for defining the operating state of your LINUX or UNIX-based operating system. Each runlevel designates a different system configuration and allows access to different combinations of processes.

The important thing to note here is that there are differences in the runlevels according to the operating system. The standard LINUX kernel supports these seven different runlevels :