Linux命令学习总结：shutdown

命令简介：该命令可以安全关闭或者重新启动系统。你没有看错，shutdown命令不仅可以关闭系统、也可以重启Linux系统。命令语法：/sbin/shutdown[-tsec][-arkhncfFHP]time[warning-message]命令参数：

参数	长参数	描叙
-a		Use/etc/shutdown.allow.
-c		中断关机：当执行"shutdown-h12:00"指令时，只要按+键就可以中断关机的指令
-f		重新启动时不进行磁盘检测（fsck）
-F		重新启动时进行磁盘检测（fsck）
-h		关闭电源
-k		模拟关机（不是真的关机），只是向登录者发送警告信息出去！
-n		不调用init进程进行关机，而是强行关机
-r		关闭系统然后重新启动，类似于Windows平台restart
-t		延迟关机的时间
-w		仅做测试，并不真的将系统重新开机，只会把重开机的数据写入/var/log目录下的wtmp记录文件
	--help	显示命令在线帮助

使用示例：1:查看reboot命令的帮助信息[root@db-server~]#shutdown--help
shutdown:invalidoption---
Usage:shutdown[-akrhHPfnc][-tsecs]time[warningmessage]
-a:use/etc/shutdown.allow
-k:don'treallyshutdown,onlywarn.
-r:rebootaftershutdown.
-h:haltaftershutdown.
-P:haltactionistoturnoffpower.
-H:haltactionistojusthalt.
-f:doa'fast'reboot(skipfsck).
-F:Forcefsckonreboot.
-n:donotgothrough"init"butgodownrealfast.
-c:cancelarunningshutdown.
-tsecs:delaybetweenwarningandkillsignal.
**the"time"argumentismandatory!(try"now")**
[root@db-server~]#

[root@db-server~]#manshutdown

SHUTDOWN(8)LinuxSystemAdministrator鈥檚ManualSHUTDOWN(8)

NAME

shutdown-bringthesystemdown

SYNOPSIS

/sbin/shutdown[-tsec][-arkhncfFHP]time[warning-message]

DESCRIPTION

shutdownbringsthesystemdowninasecureway.Alllogged-inusersarenotifiedthatthesystemisgoing

down,andlogin(1)isblocked.Itispossibletoshutthesystemdownimmediatelyorafteraspecifieddelay.

AllprocessesarefirstnotifiedthatthesystemisgoingdownbythesignalSIGTERM.Thisgivesprogramslike

vi(1)thetimetosavethefilebeingedited,mailandnewsprocessingprogramsachancetoexitcleanly,etc.

shutdowndoesitsjobbysignallingtheinitprocess,askingittochangetherunlevel.Runlevel0isusedto

haltthesystem,runlevel6isusedtorebootthesystem,andrunlevel1isusedtoputtosystemintoastate

whereadministrativetaskscanbeperformed;thisisthedefaultifneitherthe-hor-rflagisgiventoshut-

down.Toseewhichactionsaretakenonhaltorrebootseetheappropriateentriesfortheserunlevelsinthe

file/etc/inittab.

OPTIONS

-aUse/etc/shutdown.allow.

-tsecTellinit(8)towaitsecsecondsbetweensendingprocessesthewarningandthekillsignal,before

changingtoanotherrunlevel.

-kDon鈥檛reallyshutdown;onlysendthewarningmessagestoeverybody.

-rRebootaftershutdown.

-hHaltorpoweroffaftershutdown.

-HHaltactionistohaltordropintobootmonitoronsystemsthatsupportit.

-PHaltactionistoturnoffthepower.

-n[DEPRECATED]Don鈥檛callinit(8)todotheshutdownbutdoitourself.Theuseofthisoptionisdis-

couraged,anditsresultsarenotalwayswhatyou鈥檇expect.

-fSkipfsckonreboot.

-FForcefsckonreboot.

-cCancelanalreadyrunningshutdown.Withthisoptionitisofcoursenotpossibletogivethetimeargu-

ment,butyoucanenteraexplanatorymessageonthecommandlinethatwillbesenttoallusers.

timeWhentoshutdown.

warning-message

Messagetosendtoallusers.

Thetimeargumentcanhavedifferentformats.First,itcanbeanabsolutetimeintheformathh:mm,inwhich

hhisthehour(1or2digits)andmmistheminuteofthehour(intwodigits).Second,itcanbeinthefor-

mat+m,inwhichmisthenumberofminutestowait.Thewordnowisanaliasfor+0.

Ifshutdowniscalledwithadelay,itcreatestheadvisoryfile/etc/nologinwhichcausesprogramssuchas

login(1)tonotallownewuserlogins.Shutdownremovesthisfileifitisstoppedbeforeitcansignalinit

(i.e.itiscancelledorsomethinggoeswrong).Italsoremovesitbeforecallinginittochangetherunlevel.

The-fflagmeans鈥榬ebootfast鈥?Thisonlycreatesanadvisoryfile/fastbootwhichcanbetestedbythesys-

temwhenitcomesupagain.Thebootrcfilecantestifthisfileispresent,anddecidenottorunfsck(1)

sincethesystemhasbeenshutdownintheproperway.Afterthat,thebootprocessshouldremove/fastboot.

The-Fflagmeans鈥榝orcefsck鈥?Thisonlycreatesanadvisoryfile/forcefsckwhichcanbetestedbythesys-

temwhenitcomesupagain.Thebootrcfilecantestifthisfileispresent,anddecidetorunfsck(1)with

aspecial鈥榝orce鈥?flagsothatevenproperlyunmountedfilesystemsgetchecked.Afterthat,thebootprocess

shouldremove/forcefsck.

The-nflagcausesshutdownnottocallinit,buttokillallrunningprocessesitself.shutdownwillthen

turnoffquota,accounting,andswappingandunmountallfilesystems.

ACCESSCONTROL

shutdowncanbecalledfrominit(8)whenthemagickeysCTRL-ALT-DELarepressed,bycreatinganappropriate

entryin/etc/inittab.Thismeansthateveryonewhohasphysicalaccesstotheconsolekeyboardcanshutthe

systemdown.Topreventthis,shutdowncanchecktoseeifanauthorizeduserisloggedinononeofthevir-

tualconsoles.Ifshutdowniscalledwiththe-aargument(addthistotheinvocationofshutdownin/etc/init-

tab),itcheckstoseeifthefile/etc/shutdown.allowispresent.Itthencomparestheloginnamesinthat

filewiththelistofpeoplethatareloggedinonavirtualconsole(from/var/run/utmp).Onlyifoneofthose

authorizedusersorrootisloggedin,itwillproceed.Otherwiseitwillwritethemessage

shutdown:noauthorizedusersloggedin

tothe(physical)systemconsole.Theformatof/etc/shutdown.allowisoneusernameperline.Emptylinesand

commentlines(prefixedbya#)areallowed.Currentlythereisalimitof32usersinthisfile.

Notethatif/etc/shutdown.allowisnotpresent,the-aargumentisignored.

HALTORPOWEROFF

The-HoptionjustsetstheinitenvironmentvariableINIT_HALTtoHALT,andthe-Poptionjustsetsthatvari-

abletoPOWEROFF.Theshutdownscriptthatcallshalt(8)asthelastthingintheshutdownsequenceshould

checktheseenvironmentvariablesandcallhalt(8)withtherightoptionsfortheseoptionstoactuallyhave

anyeffect.Debian3.1(sarge)supportsthis.

FILES

/fastboot

/etc/inittab

/etc/init.d/halt

/etc/init.d/reboot

/etc/shutdown.allow

NOTES

Alotofusersforgettogivethetimeargumentandarethenpuzzledbytheerrormessageshutdownproduces.

Thetimeargumentismandatory;in90percentofallcasesthisargumentwillbethewordnow.

InitcanonlycaptureCTRL-ALT-DELandstartshutdowninconsolemode.IfthesystemisrunningtheXwindow

System,theXserverprocessesallkeystrokes.SomeX11environmentsmakeitpossibletocaptureCTRL-ALT-DEL,

butwhatexactlyisdonewiththateventdependsonthatenvironment.

Shutdownwasn鈥檛designedtoberunsetuid./etc/shutdown.allowisnotusedtofindoutwhoisexecutingshut-

down,itONLYcheckswhoiscurrentlyloggedinon(oneofthe)console(s).

AUTHOR

MiquelvanSmoorenburg,miquels@cistron.nl

SEEALSO

fsck(8),init(8),halt(8),poweroff(8),reboot(8)

November12,2003SHUTDOWN(8)

(END)

2：马上关闭Linux系统，其中now相当于时间为0的状态

[root@db-server~]#shutdown-hnow

Broadcastmessagefromroot(pts/1)(SatJan1018:51:342015):

ThesystemisgoingdownforsystemhaltNOW!

3：系统2分钟后重新启动，其中+m表示几分钟后关机或开机。

[root@db-server~]#shutdown-r+2

Broadcastmessagefromroot(pts/2)(SatJan1019:56:002015):

ThesystemisgoingDOWNforrebootin2minutes!

4：设置系统在那个时间点关机

[root@db-server~]#shutdown-h12:30

或

[root@db-server~]#shutdown-h12:30&

[1]4578

最好是使用命令&将关机命令至于后台处理。不影响当前其它操作。
设置多久时间后执行shutdown命令。时间参数有hh：mm或+m两种模式。hh：mm格式表示在几点几分执行shutdown命令。例如“shutdown10：45”表示将在10：45执行shutdown.+m表示m分钟后执行shutdown.比较特别的用法是以now表示立即执行shutdown.值得注意的是这部分参数不能省略。另外，需要注意如果现在已经22:30，你执行了shutdown-h22:00&那么第二天才会关机。

5：将前一个shutdown命令取消息

如下所示，执行了下面命令让Linux在12:30关机，但是如果发现这个时间点不合适，那么可以使用CTRL+C取消
[root@db-server~]#shutdown-h12:30

Shutdowncancelled.
[root@db-server~]#
也可以在另外一个命令窗口执行下面命令
[root@db-server~]#shutdown-c

6：向所有登录的用户发出信息

[root@db-server~]#shutdown-k"now"

Broadcastmessagefromroot(pts/2)(SatJan1020:09:142015):

ThesystemisgoingdowntomaintenancemodeNOW!

Shutdowncancelled.

另外登录的会话窗口会收到如下信息

[root@db-server~]#

[root@db-server~]#

Broadcastmessagefromroot(pts/2)(SatJan1020:11:342015):

ThesystemisgoingdowntomaintenancemodeNOW!

一般使用下面语法，如下所示

[root@db-server~]#shutdown-know"TheServerwillshutdownnow"

Broadcastmessagefromroot(pts/1)(SatJan1020:14:542015):

TheServerwillshutdownnow

ThesystemisgoingdowntomaintenancemodeNOW!

Shutdowncancelled.

7：重新启动时不进行磁盘检测

[root@db-server~]#shutdown-frnow

Broadcastmessagefromroot(pts/1)(SatJan1020:23:592015):

ThesystemisgoingdownforrebootNOW!

8：在多少秒后关闭系统并给用户发送提示信息

[root@db-server~]#shutdown-t10-hnow"Systemwillshutdown10sencondlater"

Broadcastmessagefromroot(pts/1)(SatJan1020:33:362015):

Systemwillshutdown10sencondlater

ThesystemisgoingdownforsystemhaltNOW!