Linux指令：shutdown

指令簡介：

此指令可以安全關閉或重新啟動系統。你沒有看錯，shutdown指令不僅可以關閉系統、也可以重新啟動Linux系統。

 

指令語法：

/sbin/shutdown [-t sec] [-arkhncfFHP] time [warning-message]

1: 查看reboot指令的幫助資訊

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

shutdown: invalid option -- -

Usage:    shutdown [-akrhHPsecncs] [time message]

                  -a:      use/etc/shutdown.allow

   ally shutdown, only warn.

                  -r:      reboot   alt after shutdown.

                  -P:      halt action is to turn off power.

                  -H:      halt action is to just halt.    a 'fast' reboot (skip fsck).

                  -F:          do not go through "init" but go down real fast.
                  -c:      cancel a running shut warning and kill signal.
                  ** the "time" argument is mandatory! (try "now") **
[root@ db-server ~]#

[root@db-server ~]# man shutdown
SHUTDOWN(8)           Linux System Administrator鈥檚 Manual          SHUTDOWN(8)
 
NAME
       shutdown - bring the system down
 
SYNOPSIS
       /sbin/shutdown [-t sec] [-arkhncfFHP] time [warning-message]
 
DESCRIPTION
       shutdown  brings  the  system  down in a secure way.  All logged-in users are notified that the system is going
       down, and login(1) is blocked.  It is possible to shut the system down immediately or after a specified  delay.
       All processes are first notified that the system is going down by the signal SIGTERM.  This gives programs like
       vi(1) the time to save the file being edited, mail and news processing programs a chance to exit cleanly,  etc.
       shutdown  does its job by signalling the init process, asking it to change the runlevel.  Runlevel 0 is used to
       halt the system, runlevel 6 is used to reboot the system, and runlevel 1 is used to put to system into a  state
       where administrative tasks can be performed; this is the default if neither the -h or -r flag is given to shut-
       down.  To see which actions are taken on halt or reboot see the appropriate entries for these runlevels in  the
       file /etc/inittab.
 
OPTIONS
       -a     Use /etc/shutdown.allow.
 
       -t sec Tell  init(8)  to  wait  sec  seconds  between sending processes the warning and the kill signal, before
              changing to another runlevel.
 
       -k     Don鈥檛 really shutdown; only send the warning messages to everybody.
 
       -r     Reboot after shutdown.
 
       -h     Halt or poweroff after shutdown.
 
       -H     Halt action is to halt or drop into boot monitor on systems that support it.
 
       -P     Halt action is to turn off the power.
 
       -n     [DEPRECATED] Don鈥檛 call init(8) to do the shutdown but do it ourself.  The use of this  option  is  dis-
              couraged, and its results are not always what you鈥檇 expect.
 
       -f     Skip fsck on reboot.
 
       -F     Force fsck on reboot.
 
       -c     Cancel an already running shutdown. With this option it is of course not possible to give the time argu-
              ment, but you can enter a explanatory message on the command line that will be sent to all users.
 
       time   When to shutdown.
 
       warning-message
              Message to send to all users.
 
       The time argument can have different formats.  First, it can be an absolute time in the format hh:mm, in  which
       hh is the hour (1 or 2 digits) and mm is the minute of the hour (in two digits).  Second, it can be in the for-
       mat +m, in which m is the number of minutes to wait.  The word now is an alias for +0.
 
       If shutdown is called with a delay, it creates the advisory file /etc/nologin which  causes  programs  such  as
       login(1)  to  not  allow new user logins. Shutdown removes this file if it is stopped before it can signal init
       (i.e. it is cancelled or something goes wrong).  It also removes it before calling init to change the runlevel.
 
       The  -f flag means 鈥榬eboot fast鈥?  This only creates an advisory file /fastboot which can be tested by the sys-
       tem when it comes up again.  The boot rc file can test if this file is present, and decide not to  run  fsck(1)
       since the system has been shut down in the proper way.  After that, the boot process should remove /fastboot.
 
       The  -F flag means 鈥榝orce fsck鈥?  This only creates an advisory file /forcefsck which can be tested by the sys-
       tem when it comes up again.  The boot rc file can test if this file is present, and decide to run fsck(1)  with
       a  special  鈥榝orce鈥?flag so that even properly unmounted filesystems get checked.  After that, the boot process
       should remove /forcefsck.
 
       The -n flag causes shutdown not to call init, but to kill all running processes  itself.   shutdown  will  then
       turn off quota, accounting, and swapping and unmount all filesystems.
 
ACCESS CONTROL
       shutdown  can  be  called from init(8) when the magic keys CTRL-ALT-DEL are pressed, by creating an appropriate
       entry in /etc/inittab. This means that everyone who has physical access to the console keyboard  can  shut  the
       system  down.  To prevent this, shutdown can check to see if an authorized user is logged in on one of the vir-
       tual consoles. If shutdown is called with the -a argument (add this to the invocation of shutdown in /etc/init-
       tab),  it  checks  to see if the file /etc/shutdown.allow is present.  It then compares the login names in that
       file with the list of people that are logged in on a virtual console (from /var/run/utmp). Only if one of those
       authorized users or root is logged in, it will proceed. Otherwise it will write the message
 
       shutdown: no authorized users logged in
 
       to  the (physical) system console. The format of /etc/shutdown.allow is one user name per line. Empty lines and
       comment lines (prefixed by a #) are allowed. Currently there is a limit of 32 users in this file.
 
       Note that if /etc/shutdown.allow is not present, the -a argument is ignored.
 
HALT OR POWEROFF
       The -H option just sets the init environment variable INIT_HALT to HALT, and the -P option just sets that vari-
       able  to  POWEROFF.  The  shutdown  script that calls halt(8) as the last thing in the shutdown sequence should
       check these environment variables and call halt(8) with the right options for these options  to  actually  have
       any effect.  Debian 3.1 (sarge) supports this.
 
FILES
       /fastboot
       /etc/inittab
       /etc/init.d/halt
       /etc/init.d/reboot
       /etc/shutdown.allow
 
NOTES
       A  lot  of  users forget to give the time argument and are then puzzled by the error message shutdown produces.
       The time argument is mandatory; in 90 percent of all cases this argument will be the word now.
 
       Init can only capture CTRL-ALT-DEL and start shutdown in console mode.  If the system is running the  X  window
       System, the X server processes all key strokes. Some X11 environments make it possible to capture CTRL-ALT-DEL,
       but what exactly is done with that event depends on that environment.
 
       Shutdown wasn鈥檛 designed to be run setuid. /etc/shutdown.allow is not used to find out who is  executing  shut-
       down, it ONLY checks who is currently logged in on (one of the) console(s).
 
AUTHOR
       Miquel van Smoorenburg, miquels@cistron.nl
 
SEE ALSO
       fsck(8), init(8), halt(8), poweroff(8), reboot(8)
 
                               November 12, 2003                   SHUTDOWN(8)
(END)

2：馬上關閉Linux系統，其中now 相當於時間為0 的狀態

[root@db-server ~]# shutdown -h now
 
Broadcast message from root (pts/1) (Sat Jan 10 18:51:34 2015):
 
The system is going down for system halt NOW!

3：系統2分鐘後重新啟動，其中+m表示幾分鐘後關機或開機。

[root@db-server ~]# shutdown -r +2
 
Broadcast message from root (pts/2) (Sat Jan 10 19:56:00 2015):
 
The system is going DOWN for reboot in 2 minutes!

4：設定係統在那個時間點關機

[root@db-server ~]# shutdown -h 12:30
 
或
 
[root@db-server ~]# shutdown -h 12:30 &
[1] 4578

最好是使用指令&將關機指令至於後台處理。不影響當前其它操作。

設定多久時間後執行shutdown指令。時間參數有hh：mm或+m兩種模式。 hh：mm格式表示在幾點幾分執行shutdown指令。例如 「shutdown 10：45」表示將在10：45執行shutdown.+m表示m分鐘後執行shutdown.比較特別的用法是以now表示立即執行shutdown. 值得注意的是這部分參數不能省略。另外，要注意如果現在已經22:30，你執行了shutdown -h 22:00 & 那麼第二天才會關機。

 

5：將前一個shutdown命令取訊息

如下所示，執行了下面命令讓Linux在12:30關機，但是如果發現這個時間點不合適，那麼可以使用CTRL+C取消

[root@db-server ~]# shutdown -h 12:30

Shutdown cancelled.

[root@db-server ~]#

指令也可以在另外一個指令[root@db-server ~]# shutdown -c

 

6：向所有登入的使用者發出訊息

[root@db-server ~]# shutdown -k "now"
 
Broadcast message from root (pts/2) (Sat Jan 10 20:09:14 2015):
 
The system is going down to maintenance mode NOW!
 
Shutdown cancelled.

另外登入的會話視窗會收到以下訊息

[root@db-server ~]# 
[root@db-server ~]# 
Broadcast message from root (pts/2) (Sat Jan 10 20:11:34 2015):
 
The system is going down to maintenance mode NOW!

一般使用下面語法，如下所使用下面語法顯示

[root@db-server ~]# shutdown -k now "The Server will shutdown now"
 
Broadcast message from root (pts/1) (Sat Jan 10 20:14:54 2015):
 
The Server will shutdown now 
The system is going down to maintenance mode NOW!
 
Shutdown cancelled.

7：重新啟動時不進行磁碟偵測

[root@db-server ~]# shutdown -fr now
 
Broadcast message from root (pts/1) (Sat Jan 10 20:23:59 2015):
 
The system is going down for reboot NOW!

8：在多少秒後關閉系統並給使用者發送提示訊息

[root@db-server ~]# shutdown -t 10 -h now "System will shutdown 10 sencond later"
 
Broadcast message from root (pts/1) (Sat Jan 10 20:33:36 2015):
 
System will shutdown 10 sencond later 
The system is going down for system halt NOW!