Editing Runlevel (section)

== Linux ==
Although systemd is, {{As of|2016|lc=yes}}, used by default in most major [[Linux]] distributions, runlevels can still be used through the means provided by the [[sysvinit]] project.  After the [[Linux kernel]] has booted, the {{Mono|/sbin/init}} program reads the {{Mono|/etc/inittab}} file to determine the behavior for each runlevel.  Unless the user specifies another value as a [[Linux kernel boot parameters|kernel boot parameter]], the system will attempt to enter (start) the default runlevel.

=== Linux Standard Base specification ===
Systems conforming to the [[Linux Standard Base]] (LSB) need not provide the exact run levels given here or give them the meanings described here, and may map any level described here to a different level which provides the equivalent functionality.<ref>
{{cite web | url = http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/runlevels.html | title = Chapter 20. System Initialization 20.5. Run Levels 
| work = [[Linux Standard Base]] Core Specification 4.1 | year = 2011 | access-date = 2011-04-21}}
</ref>

{| class="wikitable"
|+LSB 4.1.0
|-
!ID
!Name
!Description
|-
|'''0'''
|Off
|Turns off the device.
|-
|'''1'''
|Single-user mode
|Mode for administrative tasks.<ref>{{cite web | url = http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/shutdown.html | title = Chapter 15. Commands and Utilities 15.2. Command Behavior | work = Linux Standard Base Core Specification 4.1 | year = 2011 | access-date = 2011-04-21}}</ref>{{Efn|The additional behavior of runlevel 1 varies greatly.  All distributions provide at least one virtual terminal.  Some distributions start a login shell as the [[superuser]]; some require correctly entering the superuser's password; others provide a login prompt, allowing access to any registered user.}}
|-
|'''2'''
|Multi-user mode
|Does not configure network interfaces and does not export networks services.{{Efn|In some cases, runlevels 2 and 3 function identically, offering a multi-user mode with networking.}}
|-
|'''3'''
|Multi-user mode with networking
|Starts the system normally.{{ref|behavior_of_runlevel_23}}
|-
|'''4'''
|Not used/user-definable
|For special purposes.
|-
|'''5'''
|Full mode
|Same as runlevel 3 + [[X display manager (program type)|display manager]].
|-
|'''6'''
|Reboot
|Reboots the device.
|}

=== Slackware Linux ===
[[Slackware Linux]] uses runlevel 1 for maintenance, as on other Linux distributions;  runlevels 2, 3 and 5 identically configured for a console (with all services active); and runlevel 4 adds the X Window System.

{| class="wikitable"
|+Slackware Linux runlevels<ref name="slackware_boot">{{cite web
| title = Slackware Linux Runlevels
| url = http://slackware.com/config/init.php
| access-date = 2013-06-11}}</ref>
|-
!ID
!Description
|-
|'''0'''
|Off
|-
|'''1'''
|Single-user mode
|-
|'''2'''
|Unused but configured the same as runlevel 3
|-
|'''3'''
|Multi-user mode without display manager
|-
|'''4'''
|Multi-user mode with display manager (X11 or a session manager)
|-
|'''5'''
|Full mode
|-
|'''6'''
|Reboot
|}

=== Gentoo Linux ===
{| class="wikitable"
|+[[Gentoo Linux]] runlevels<ref name="gentoo_boot">{{cite web
| title = Gentoo Linux Runlevels
| url = http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=2&chap=4
| access-date = 2013-06-11}}</ref>
|-
!ID
!Description
|-
|'''0'''
|Off
|-
|'''1''' or''' S'''
|Single-user mode
|-
|'''2'''
|Multi-user mode without networking.
|-
|'''3'''
|Multi-user mode
|-
|'''4'''
|Aliased for runlevel 3
|-
|'''5'''
|Full mode
|-
|'''6'''
|Reboot
|}

=== Debian GNU/Linux ===
{| class="wikitable" style="width:20em"
|+[[Debian GNU/Linux]] runlevels<ref>{{cite web
| title = Debian runlevel manpage
| url = https://manpages.debian.org/man/8/runlevel
| access-date = 2021-10-31}}</ref>
|-
!ID
!Description
|-
|'''0'''
|Off
|-
|'''1'''
|Recovery mode
|-
|'''2,3,4'''
|Partial mode
|-
|'''5'''
|Full mode
|-
|'''6'''
|Reboot
|}