Editing Runlevel (section)

== Unix ==

=== System V Releases 3 and 4 ===
{| class="wikitable"
|+[[System V]] runlevels
|-
!ID
!Description
|-
|'''0'''
|Off
|-
|'''1'''
|Single-user mode, all filesystems unmounted but not root, all processes except console processes killed
|-
|'''2'''
|Multi-user mode
|-
|'''3'''
|Multi-user mode with [[Remote File System|RFS]] (and [[Network File System (protocol)|NFS]] in Release 4) filesystems exported
|-
|'''4'''
|Multi-user, User-definable
|-
|'''5'''
|Go to firmware
|-
|'''6'''
|Reboot
|-
|'''s''', '''S'''
|Identical to '''1''', except current terminal acts as the system console
|}

=== Solaris ===
Starting from Solaris 10, SMF ([[Service Management Facility]]) is used instead of SVR4 run levels. The latter are emulated to preserve compatibility with legacy startup scripts.<ref name="solaris_boot">{{cite web
| title = Solaris Boot Process
| url = https://blogs.oracle.com/boot/entry/amrita_sadhukhan
| author = Amrita Sadhukhan
| publisher = [[Sun Microsystems|Sun]]
| access-date = 2009-08-19
| archive-date = 2013-07-09
| archive-url = https://web.archive.org/web/20130709063354/https://blogs.oracle.com/boot/entry/amrita_sadhukhan
| url-status = dead
}}</ref>

{| class="wikitable"
|+[[Solaris (operating system)|Solaris]] runlevels
!ID
!Description
|-
|'''0'''
|On SPARC systems, it returns to firmware, while on x86 systems, it shuts off the machine. If the user presses Enter, the system reboots.
|-
|'''S'''
|Single-user mode with only root filesystem mounted (as read-only) -- Solaris 10+: svc:/milestone/single-user
|-
|'''1'''
|Single-user mode with all local filesystems mounted (read-write)
|-
|'''2'''
|Multi-user mode with most daemons started – Solaris 10+: svc:/milestone/multi-user
|-
|'''3'''
|Multi-user mode; identical to '''2''' (runlevel '''3''' runs both {{mono|/sbin/rc2}} and {{mono|/sbin/rc3}}), with filesystems exported, plus some other network services started. -- Solaris 10+: svc:/milestone/multi-user-server
|-
|'''4'''
|Alternative Multi-user mode, User-definable
|-
|'''5'''
|Off
|-
|'''6'''
|Reboot
|}

=== HP-UX ===
{| class="wikitable"
|+[[HP-UX]] runlevels
|-
!ID
!Description
|-
|'''0'''
|Off
|-
|'''S'''
|Single-user mode, booted to system console only, with only root filesystem mounted (as read-only)
|-
|'''s'''
|Single-user mode, identical to '''S''' except the current terminal acts as the system console
|-
|'''1'''
|Single-user mode with local filesystems mounted (read-write)
|-
|'''2'''
|Multi-user mode with most [[Daemon (computer software)|daemons]] started and [[Common Desktop Environment]] launched
|-
|'''3'''
|Identical to runlevel '''2''' with NFS exported
|-
|'''4'''
|Multi-user mode with [[Visual User Environment|VUE]] started instead of CDE
|-
|'''5''', '''6'''
|Not used/User-definable
|}

=== AIX ===
[[AIX (operating system)|AIX]] does not follow the [[System V]] R4 (SVR4) runlevel specification, with runlevels from 0 to 9 available, as well as from a to c (or h). 0 and 1 are reserved, 2 is the default normal multi-user mode and runlevels from 3 to 9 are free to be defined by the administrator. Runlevels from a to c (or h) allow the execution of processes in that runlevel without killing processes started in another.

{| class="wikitable"
|+AIX runlevels
|-
!ID
!Name
!Description
|-
|0
|
|reserved
|-
|1
|
|reserved
|-
|2
|Normal Multi-user mode
|default mode
|}

The S, s, M and m runlevels are not true runlevels, but are used to tell the init command to enter maintenance mode. When the system enters maintenance mode from another runlevel, only the system console is used as the terminal.