Editing Init (section)

=== Runlevels ===
{{Details|Runlevel}}

The [[runlevel]]s in System&nbsp;V describe certain states of a machine, characterized by the processes and daemons running in each of them. In general, there are seven runlevels, out of which three runlevels are considered "standard", as they are essential to the operation of a system:
{{ordered list
|item1_value=0 | [[Shutdown (computing)|Turn off]]
|item2_value=1 | [[Single-user mode]] (also known as ''S'' or ''s'')
|item3_value=6 | [[Reboot (computing)|Reboot]]
}}
Aside from these standard ones, Unix and Unix-like systems treat runlevels somewhat differently. The common denominator, the <code>/etc/inittab</code> file, defines what each configured runlevel does in a given system.