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

命令参数：

使用示例：

1: 查看reboot命令的帮助信息

[root@db-server ~]# shutdown --helpshutdown: invalid option -- -Usage: shutdown [-akrhHPfnc] [-t secs] time [warning message] -a: use /etc/shutdown.allow -k: don't really shutdown, only warn. -r: reboot after shutdown. -h: halt after shutdown. -P: halt action is to turn off power. -H: halt action is to just halt. -f: do a 'fast' reboot (skip fsck). -F: Force fsck on reboot. -n: do not go through "init" but go down real fast. -c: cancel a running shutdown. -t secs: delay between 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 defaultif 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)