162:
140:
43:
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404:. At least one runlevel is the normal operating state of the system; typically, other runlevels represent single-user mode (used for repairing a faulty system), system shutdown, and various other states. Switching from one runlevel to another causes a per-runlevel set of scripts to be run, which typically mount filesystems, start or stop
643:
On Unix systems, changing the runlevel is achieved by starting only the missing services (as each level defines only those that are started / stopped). 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.
430:
in System 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:
313:
file determines what programs are run by init. The advantage of this system is that it is simple and easy to edit manually. However, new software added to the system may require changes to existing files that risk producing an unbootable system.
359:
directory. Unlike System V's script ordering, which is derived from the filename of each script, this system uses explicit dependency tags placed within each script. The order in which scripts are executed is determined by the
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Traditionally, one of the major drawbacks of init is that it starts tasks serially, waiting for each to finish loading before moving on to the next. When startup processes end up
1433:
1523:
1086:
814:, a software suite, full replacement for init in Linux that includes an init daemon, with concurrent starting of services, service manager, and other features.
656:(I/O) blocked, this can result in long delays during boot. Speeding up I/O, e.g. by using SSDs, may shorten the delays but it does not address the root cause.
1325:
262:
Since then, several additional init implementations have been created, attempting to address design limitations in the traditional versions. These include
1148:
1516:
749:, a process spawner that utilizes system-provided init, while providing process isolation, parallelized startup, and service dependency; used by
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On Linux distributions defaulting to runlevel 5 in the table on the right, runlevel 5 invokes a multiuser graphical environment running the
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Various efforts have been made to replace the traditional init daemons to address this and other design problems, including:
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Aside from these standard ones, Unix and Unix-like systems treat runlevels somewhat differently. The common denominator, the
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employed a traditional init that was somewhat compatible with System V, while some distributions such as
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will occur if the kernel is unable to start it, or it should die for any reason. Init is typically assigned
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operating systems typically reserve runlevel 5 to shut down and automatically power off the machine.
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service and daemon manager which provides asynchronous, dependency-based initialisation; written in
770:, a cross-platform full replacement for init with parallel starting of services, used by default in
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1627:
884:
805:
788:
starting with
Solaris 10, but launched as the only service by the original System V-style init
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introduced a new style of system startup configuration, which survived (with modifications) into
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1006:
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325:
181:
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and used by them until 2014. It was also used in Fedora 9, Red Hat
Enterprise Linux 6 and
204:
process that continues running until the system is shut down. It is the direct or indirect
1501:
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At any moment, a running System V is in one of the predetermined number of states, called
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329:
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143:
830:, a full replacement of init designed to start processes asynchronously. Initiated by
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743:(it launches SystemStarter to run old-style 'rc.local' and SystemStarter processes)
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169:
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711:, a single-threaded Linux init system focused on simplicity and service management
100:
239:, the design of init has diverged from the functionality provided by the init in
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42:
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utility that selects which SysV-style init scripts will be run in each runlevel
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663:
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On most systems, all users can check the current runlevel with either the
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717:, a full replacement of init designed to start processes asynchronously
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and meant to be interactively hackable during normal system operation
780:(SMF), a complete replacement/redesign of init from the ground up in
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348:
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file, defines what each configured runlevel does in a given system.
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file that is run in a sub-shell near the end of the boot sequence.
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init was, prior to 4.3BSD, the same as
Research UNIX's init; in
177:
1505:
1195:"GitHub - davmac314/dinit: Service monitoring / "init" system"
795:
732:
36:
30:
This article is about the Unix process. For other uses, see
624:
user typically changes the current runlevel by running the
1250:
364:
utility based on the requirements stated in these tags.
355:
5.0 and successors. This system executes scripts in the
885:"Lennart Poettering on systemd's Tumultuous Ascendancy"
1480:
Solaris
Service Management Facility - Quickstart Guide
820:, a process spawner started by the BSD-style init in
208:
of all other processes and automatically adopts all
1626:
1575:
1544:
1429:
757:and its derivatives, and available as an option in
340:, BSD variants have long supported a site-specific
1668:Unix process- and task-management-related software
1490:A history of modern init systems (1992–2015)
255:use BSD-style startup scripts, and others such as
808:, a software suite that includes an init system.
1172:. Unixhelp.ed.ac.uk. 1997-05-27. Archived from
395:and is therefore called the "SysV-style init".
520:3 (console/server/multiuser) or 4 (graphical)
387:When compared to its predecessors, AT&T's
1517:
8:
332:on graphical terminals under the control of
247:derivatives. Up until the early 2010s, most
1399:Red Hat Enterprise Linux 6: Technical Notes
1141:Oracle Solaris Administration: Common Tasks
846:As of February 2019, systemd has been
347:A fully modular system was introduced with
1524:
1510:
1502:
473:
705:Dinit, a service manager and init system.
127:Learn how and when to remove this message
1053:"Unix and Linux startup scripts, Part 2"
636:file sets the default runlevel with the
876:
63:Please improve this article by adding
1474:A paper summarizing Unix init schemes
1059:from the original on 18 December 2009
7:
1170:"UNIX man pages : runlevel (8)"
1051:Andrew Smallshaw (7 December 2009).
336:. To remove the requirement to edit
259:have their own customized versions.
1301:"s6: why another supervision suite"
860:Operating system service management
850:by most major Linux distributions.
200:of the operating system. Init is a
305:on terminals under the control of
25:
1486: (archived December 31, 2005)
1436:from the original on 9 April 2022
1372:. Linux Weekly News. 2010-09-14.
1278:. Free Software Foundation, Inc.
824:prior to Mac OS X v10.4
324:, it added support for running a
41:
1409:from the original on 2018-08-29
1376:from the original on 2010-09-19
1352:from the original on 2022-03-27
1307:from the original on 2021-09-13
1282:from the original on 2016-02-12
1257:from the original on 2020-08-29
1232:from the original on 2014-08-02
1207:from the original on 2021-12-12
1151:from the original on 2016-04-10
1118:from the original on 2020-12-03
1089:from the original on 2021-07-27
895:from the original on 2018-11-08
165:Version 7 Unix: contents of an
1370:"Fedora defers systemd to F15"
309:. There are no runlevels; the
1:
867:— an equivalent in Windows NT
412:, shutdown the machine, etc.
293:init runs the initialization
286:Research Unix-style/BSD-style
65:secondary or tertiary sources
1276:"The Shepherd - GNU Project"
1226:"Epoch Init System Homepage"
723:, a replacement for init in
699:before it was replaced with
1616:Service Management Facility
1345:Fedora 14 Accepted Features
778:Service Management Facility
268:Service Management Facility
1684:
1114:. Gentoo.org. 2014-12-13.
1112:Gentoo Linux Documentation
677:embedded operating systems
419:
29:
1576:Operating-system-specific
865:Session Manager Subsystem
212:. Init is started by the
1545:Portable implementations
741:Mac OS X v10.4
231:In Unix systems such as
454:
440:
435:
1251:"Void Linux main page"
384:
173:
158:
52:relies excessively on
1469:FreeBSD init man page
648:Other implementations
420:Further information:
375:
164:
142:
32:INIT (disambiguation)
27:UNIX system component
408:, start or stop the
1628:Process supervision
249:Linux distributions
1533:Service management
1495:2015-10-11 at the
822:Mac OS X
562:Releases 3.x, 4.x
526:Linux From Scratch
385:
351:1.5 and ported to
226:process identifier
210:orphaned processes
174:
159:
1655:
1654:
1015:System Manager's
969:System Manager's
586:, usually with a
580:
579:
480:Default runlevel
477:Operating system
470:Default runlevels
182:operating systems
150:listing, showing
137:
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16:(Redirected from
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1512:
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1455:Systemd#Adoption
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1328:. Archived from
1326:"s6 init system"
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598:. However, the
588:display manager
584:X Window System
536:Slackware Linux
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444:(also known as
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410:X Window System
389:UNIX System III
376:
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196:started during
192:) is the first
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1463:External links
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1348:, 2010-07-13,
1335:
1332:on 2021-09-13.
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944:Version 7 Unix
928:
921:Version 7 Unix
905:
891:. 2018-11-08.
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190:initialization
144:Version 7 Unix
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1606:SystemStarter
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1176:on 2014-07-14
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1108:"Initscripts"
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1038:File Formats
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946:Programmer's
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923:Programmer's
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919: –
916:
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890:
889:The New Stack
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638::initdefault:
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117:December 2020
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78: –
77:
73:
72:Find sources:
66:
60:
59:
55:
50:This article
48:
44:
39:
38:
33:
19:
1551:
1449:
1438:, retrieved
1428:
1422:
1411:. Retrieved
1398:
1395:"Deployment"
1389:
1378:. Retrieved
1364:
1354:, retrieved
1344:
1338:
1330:the original
1320:
1309:. Retrieved
1295:
1284:. Retrieved
1270:
1259:. Retrieved
1245:
1234:. Retrieved
1220:
1209:. Retrieved
1198:
1189:
1178:. Retrieved
1174:the original
1164:
1153:. Retrieved
1140:
1137:"Run Levels"
1131:
1120:. Retrieved
1111:
1102:
1091:. Retrieved
1082:
1073:
1061:. Retrieved
1046:
1023:
1000:
977:
954:
931:
908:
897:. Retrieved
888:
879:
845:
800:Guile Scheme
751:Alpine Linux
687:5(Rolling),
681:Alpine Linux
675:, suited to
673:busybox-init
658:
654:Input/output
651:
642:
634:/etc/inittab
608:
581:
506:Gentoo Linux
464:/etc/inittab
461:
449:
445:
425:
399:
397:
386:
377:sysv-rc-conf
361:
346:
316:
295:shell script
289:
261:
230:
222:kernel panic
189:
185:
175:
170:Bourne shell
123:
114:
104:
97:
90:
83:
71:
51:
1637:daemontools
763:Artix Linux
693:VMware ESXi
664:BootScripts
297:located at
220:process; a
216:during the
188:(short for
1440:25 January
1413:2013-12-31
1380:2010-09-17
1356:2010-07-13
1311:2021-09-13
1286:2016-01-16
1261:2020-08-31
1236:2014-07-31
1211:2021-12-12
1180:2014-07-12
1155:2017-11-14
1122:2020-12-08
1093:2015-09-12
899:2024-01-30
872:References
772:Void Linux
679:, used by
368:SysV-style
233:System III
87:newspapers
54:references
1537:Unix-like
1079:"init(8)"
668:GoboLinux
428:runlevels
416:Runlevels
401:runlevels
357:/etc/rc.d
334:/etc/ttys
307:/etc/ttys
253:Slackware
1662:Category
1612:Solaris
1493:Archived
1434:archived
1407:Archived
1374:Archived
1350:archived
1305:Archived
1280:Archived
1255:Archived
1230:Archived
1205:Archived
1149:Archived
1116:Archived
1087:Archived
1057:Archived
893:Archived
854:See also
840:ChromeOS
792:Shepherd
611:runlevel
571:UnixWare
437:Turn off
422:Runlevel
328:such as
243:and its
237:System V
206:ancestor
18:Sysvinit
1601:launchd
1591:Upstart
1586:systemd
1539:systems
1482:at the
1403:Red Hat
1030:ttys(5)
1007:init(8)
984:ttys(5)
961:init(8)
938:ttys(5)
915:init(8)
848:adopted
828:Upstart
812:systemd
786:Solaris
782:illumos
721:launchd
697:OpenWrt
640:entry.
626:telinit
604:illumos
600:Solaris
550:illumos
546:Solaris
406:daemons
362:rcorder
353:FreeBSD
338:/etc/rc
311:/etc/rc
299:/etc/rc
272:systemd
264:launchd
218:booting
198:booting
194:process
167:/etc/rc
101:scholar
1597:macOS
1582:Linux
1562:OpenRC
1557:Initng
1476:(2007)
1200:GitHub
1145:Oracle
1063:6 June
1040:Manual
1036:4.3BSD
1017:Manual
1013:4.3BSD
994:Manual
990:4.2BSD
971:Manual
967:4.2BSD
948:Manual
925:Manual
836:Google
832:Ubuntu
794:, the
759:Devuan
755:Gentoo
747:OpenRC
725:Darwin
715:Initng
691:, and
685:SliTaz
456:Reboot
349:NetBSD
322:4.3BSD
280:OpenRC
266:, the
257:Gentoo
214:kernel
202:daemon
172:script
103:
96:
89:
82:
76:"Init"
74:
1647:runit
1642:monit
1630:tools
1567:runit
768:runit
729:macOS
709:Epoch
701:procd
590:like
516:HP-UX
496:antiX
303:getty
276:Runit
108:JSTOR
94:books
1552:init
1453:See
1442:2014
1065:2011
776:Sun
761:and
737:tvOS
630:init
622:root
602:and
573:7.x
426:The
379:, a
278:and
235:and
186:init
178:Unix
154:and
152:init
148:/etc
80:news
1535:in
838:'s
796:GNU
733:iOS
666:in
628:or
616:who
613:or
596:KDM
594:or
592:GDM
486:AIX
448:or
381:TUI
318:BSD
245:BSD
228:1.
176:In
56:to
1664::
1432:,
1405:.
1401:.
1397:.
1303:.
1253:.
1228:.
1203:.
1197:.
1147:.
1143:.
1139:.
1110:.
1085:.
1081:.
1055:.
887:.
806:s6
753:,
683:,
618:-r
576:3
565:2
554:3
548:/
540:3
530:3
510:3
500:5
490:2
282:.
274:,
270:,
184:,
156:rc
146::
67:.
1525:e
1518:t
1511:v
1416:.
1383:.
1314:.
1289:.
1264:.
1239:.
1214:.
1183:.
1158:.
1125:.
1096:.
1067:.
902:.
842:.
784:/
735:/
731:/
727:/
452:)
450:s
446:S
330:X
130:)
124:(
119:)
115:(
105:·
98:·
91:·
84:·
61:.
34:.
20:)
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