linux的shutdown命令详解

学习啦在线学习网linux的shutdown命令详解

　　linux下关机我们可以采用shutdown命令来实现，下面由学习啦小编为大家搜集整理了linux的shutdown命令详解的相关知识，希望对大家有帮助!

　　linux的shutdown命令详解

　　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 [-t sec] [-arkhncfFHP] time [warning-message]

　　命令参数：

　　linux的shutdown命令使用示例

　　1: 查看reboot命令的帮助信息

学习啦在线学习网 　　[root@db-server ~]# shutdown --help

学习啦在线学习网 　　shutdown: invalid option -- -

　　Usage: shutdown [-akrhHPfnc] [-t secs] time [warning message]

　　-a: use /etc/shutdown.allow

学习啦在线学习网 　　-k: don't really shutdown, only warn.

学习啦在线学习网 　　-r: reboot after shutdown.

学习啦在线学习网 　　-h: halt after shutdown.

学习啦在线学习网 　　-P: halt action is to turn off power.

　　-H: halt action is to just halt.

学习啦在线学习网 　　-f: do a 'fast' reboot (skip fsck).

　　-F: Force fsck on reboot.

　　-n: do not go through "init" but go down real fast.

学习啦在线学习网 　　-c: cancel a running shutdown.

　　-t secs: delay between warning and kill signal.

　　** the "time" argument is mandatory! (try "now") **

学习啦在线学习网 　　[root@db-server ~]#

学习啦在线学习网 　　[root@db-server ~]# man shutdown

学习啦在线学习网 　　SHUTDOWN(8) Linux System Administrator鈥檚 Manual SHUTDOWN(8)

　　NAME

　　shutdown - bring the system down

　　SYNOPSIS

学习啦在线学习网 　　/sbin/shutdown [-t sec] [-arkhncfFHP] time [warning-message]

　　DESCRIPTION

学习啦在线学习网 　　shutdown brings the system down in a secure way. All logged-in users are notified that the system is going

学习啦在线学习网 　　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.

学习啦在线学习网 　　shutdown does its job by signalling the init process, asking it to change the runlevel. Runlevel 0 is used to

学习啦在线学习网 　　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-

学习啦在线学习网 　　down. To see which actions are taken on halt or reboot see the appropriate entries for these runlevels in the

　　file /etc/inittab.

　　OPTIONS

学习啦在线学习网 　　-a Use /etc/shutdown.allow.

　　-t sec Tell init(8) to wait sec seconds between sending processes the warning and the kill signal, before

学习啦在线学习网 　　changing to another runlevel.

学习啦在线学习网 　　-k Don鈥檛 really shutdown; only send the warning messages to everybody.

　　-r Reboot after shutdown.

学习啦在线学习网 　　-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-

学习啦在线学习网 　　couraged, and its results are not always what you鈥檇 expect.

学习啦在线学习网 　　-f Skip fsck on reboot.

学习啦在线学习网 　　-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

学习啦在线学习网 　　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.

学习啦在线学习网 　　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

学习啦在线学习网 　　(i.e. it is cancelled or something goes wrong). It also removes it before calling init to change the runlevel.

学习啦在线学习网 　　The -f flag means 鈥榬eboot fast鈥? This only creates an advisory file /fastboot which can be tested by the sys-

学习啦在线学习网 　　tem when it comes up again. The boot rc file can test if this file is present, and decide not to run fsck(1)

学习啦在线学习网 　　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-

学习啦在线学习网 　　tem when it comes up again. The boot rc file can test if this file is present, and decide to run fsck(1) with

学习啦在线学习网 　　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

学习啦在线学习网 　　turn off quota, accounting, and swapping and unmount all filesystems.

学习啦在线学习网 　　ACCESS CONTROL

学习啦在线学习网 　　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

学习啦在线学习网 　　system down. To prevent this, shutdown can check to see if an authorized user is logged in on one of the vir-

学习啦在线学习网 　　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

学习啦在线学习网 　　file with the list of people that are logged in on a virtual console (from /var/run/utmp). Only if one of those

学习啦在线学习网 　　authorized users or root is logged in, it will proceed. Otherwise it will write the message

学习啦在线学习网 　　shutdown: no authorized users logged in

学习啦在线学习网 　　to the (physical) system console. The format of /etc/shutdown.allow is one user name per line. Empty lines and

学习啦在线学习网 　　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.

学习啦在线学习网 　　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

学习啦在线学习网 　　/etc/init.d/halt

学习啦在线学习网 　　/etc/init.d/reboot

学习啦在线学习网 　　/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.

学习啦在线学习网 　　Init can only capture CTRL-ALT-DEL and start shutdown in console mode. If the system is running the X window

学习啦在线学习网 　　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.

学习啦在线学习网 　　Shutdown wasn鈥檛 designed to be run setuid. /etc/shutdown.allow is not used to find out who is executing shut-

学习啦在线学习网 　　down, it ONLY checks who is currently logged in on (one of the) console(s).

　　AUTHOR

　　Miquel van Smoorenburg, miquels@cistron.nl

学习啦在线学习网 　　SEE ALSO

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

学习啦在线学习网 　　November 12, 2003 SHUTDOWN(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 -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

　　Broadcast message from root (pts/2) (Sat Jan 10 19:56:00 2015):

　　The system is going DOWN for reboot in 2 minutes!

学习啦在线学习网 　　4：设置系统在那个时间点关机

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

　　或

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

学习啦在线学习网 　　[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 “shutdown 10：45”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 -h 22:00 & 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

学习啦在线学习网 　　[root@db-server ~]# shutdown -h 12:30

　　Shutdown cancelled.

学习啦在线学习网 　　[root@db-server ~]#

　　也可以在另外一个命令窗口执行下面命令

学习啦在线学习网 　　[root@db-server ~]# shutdown -c

　　6：向所有登录的用户发出信息

学习啦在线学习网 　　[root@db-server ~]# shutdown -k "now"

学习啦在线学习网 　　Broadcast message from root (pts/2) (Sat Jan 10 20:09:14 2015):

　　The system is going down to maintenance mode NOW!

　　Shutdown cancelled.

　　另外登录的会话窗口会收到如下信息

　　[root@db-server ~]#

学习啦在线学习网 　　[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!

学习啦在线学习网 　　一般使用下面语法，如下所示

学习啦在线学习网 　　[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

学习啦在线学习网 　　The system is going down to maintenance mode NOW!

学习啦在线学习网 　　Shutdown cancelled.

学习啦在线学习网 　　7：重新启动时不进行磁盘检测

学习啦在线学习网 　　[root@db-server ~]# shutdown -fr now

学习啦在线学习网 　　Broadcast message from root (pts/1) (Sat Jan 10 20:23:59 2015):

学习啦在线学习网 　　The system is going down for reboot NOW!

学习啦在线学习网 　　8：在多少秒后关闭系统并给用户发送提示信息

　　[root@db-server ~]# shutdown -t 10 -h now "System will shutdown 10 sencond later"

学习啦在线学习网 　　Broadcast message from root (pts/1) (Sat Jan 10 20:33:36 2015):

学习啦在线学习网 　　System will shutdown 10 sencond later

　　The system is going down for system halt NOW!