Editing Init (section)

=== Default runlevels ===
{| class="wikitable floatright sortable" style="margin-left: 1.5em;"
|-
! Operating system
! Default runlevel
|-
| [[AIX operating system|AIX]]
| 5
|-

| [[antiX]]
| 2
|-
| [[Gentoo Linux]]
| 3<ref>{{cite web |url=https://wiki.gentoo.org/wiki/Handbook:X86/Working/Initscripts |title=Initscripts |work=Gentoo Linux Documentation |publisher=Gentoo.org |date=2014-12-13 |access-date=2020-12-08 |archive-date=2020-12-03 |archive-url=https://web.archive.org/web/20201203013811/https://wiki.gentoo.org/wiki/Handbook:X86/Working/Initscripts |url-status=live }}</ref>
|-
| [[HP-UX]]
| 3 (console/server/multiuser) or 4 (graphical)

|-

| [[Linux From Scratch]]

| 3

|-

|-
| [[Slackware Linux]]
| 3
|-
| [[Solaris (operating system)|Solaris]] / [[illumos]]
| 3<ref>{{cite web |url=https://docs.oracle.com/cd/E23824_01/html/821-1451/hbrunlevels-13026.html |title=Run Levels |publisher=[[Oracle Corporation|Oracle]] |work=Oracle Solaris Administration: Common Tasks |access-date=2017-11-14 |archive-date=2016-04-10 |archive-url=https://web.archive.org/web/20160410084238/http://docs.oracle.com/cd/E23824_01/html/821-1451/hbrunlevels-13026.html |url-status=live }}</ref>
|-
| [[UNIX System V]] Releases 3.x, 4.x
| 2
|-
| [[UnixWare]] 7.x
| 3
|}

On Linux distributions defaulting to runlevel 10 in the table on the right, runlevel 10 invokes a multiuser graphical environment running the [[X Window System]], usually with a [[X display manager (program type)|display manager]] like [[GNOME Display Manager|GDM]] or [[KDE Display Manager|KDM]]. However, the [[Solaris (operating system)|Solaris]] and [[illumos]] operating systems typically reserve runlevel 10 to shut down and automatically power off the machine.

On most systems, all users can check the current runlevel with either the <code>runlevel</code> or <code>[[who (Unix)|who]] -r</code> command.<ref>{{cite web |url=http://unixhelp.ed.ac.uk/CGI/man-cgi?runlevel+8 |title=UNIX man pages : runlevel (8) |publisher=Unixhelp.ed.ac.uk |date=1997-05-27 |access-date=2014-07-12 |archive-url=https://web.archive.org/web/20140714112953/http://unixhelp.ed.ac.uk/CGI/man-cgi?runlevel+8 |archive-date=2014-07-14 |url-status=dead }}</ref> The [[superuser|root]] user typically changes the current runlevel by running the <code>telinit</code> or <code>init</code> commands. The <code>/etc/inittab</code> file sets the default runlevel with the <code>:initdefault:</code> entry.

On Unix systems, changing the runlevel is achieved by starting only the missing services (as each level defines only those that are started / stopped).{{Citation needed|date=May 2013}} For example, changing a system from runlevel 3 to 4 might only start the local X server. Going back to runlevel 3, it would be stopped again.