Linux command learning summary: explain the reboot command in detail

Command summary:

This command is used to restart the Linux system. Equivalent to the restart command in the Windows system.

Command syntax:

/sbin/reboot [-n] [-w] [-d] [-f] [-i]

or

reboot [-n] [-w] [-d] [-f] [-i]

Command parameters:

参数	长参数	描叙
-d		重新启动时不把数据写入记录文件/var/tmp/wtmp
-f		强制重新开机，不调用shutdown指令的功能。
-h		在系统关机或poweroff之前，将所有的硬盘处于待机模式
-i		关闭网络设置之后再重新启动系统
-n		保存数据后再重新启动系统
-p		When halting the system, do a poweroff. This is the default when halt is called as poweroff
-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

Use examples:

1: view the help information for the reboot command

[root@DB-Server ~]# reboot --help
usage: reboot [-n] [-w] [-d] [-f] [-h] [-i]
    -n: don't sync before halting the system
    -w: only write a wtmp reboot record and exit.
    -d: don't write a wtmp record.
    -f: force halt/reboot, don't call shutdown.
    -h: put harddisks in standby mode.
    -i: shut down all network interfaces.

[root@DB-Server ~]# man reboot

[root@DB-Server ~]# man reboot
HALT(8)        Linux System Administrator  �   �   Manual       HALT(8)
 
NAME
    halt, reboot, poweroff - stop the system.
 
SYNOPSIS
    /sbin/halt [-n] [-w] [-d] [-f] [-i] [-p] [-h]
    /sbin/reboot [-n] [-w] [-d] [-f] [-i]
    /sbin/poweroff [-n] [-w] [-d] [-f] [-i] [-h]
 
DESCRIPTION
    Halt notes that the system is being brought down in the file /var/log/wtmp, and then either tells the kernel to halt, reboot or poweroff the system.
 
    If halt or reboot is called when the system is not in runlevel 0 or 6, in other words when it  �   �   running normally, shutdown will be invoked instead (with
    the -h or -r flag). For more info see the shutdown(8) manpage.
 
    The rest of this manpage describes the behaviour in runlevels 0 and 6, that is when the systems shutdown scripts are being run.
 
OPTIONS
    -n   Don  �   �   sync before reboot or halt. Note that the kernel and storage drivers may still sync.
 
    -w   Don  �   �   actually reboot or halt but only write the wtmp record (in the /var/log/wtmp file).
 
    -d   Don  �   �   write the wtmp record. The -n flag implies -d.
 
    -f   Force halt or reboot, don  �   �   call shutdown(8).
 
    -i   Shut down all network interfaces just before halt or reboot.
 
    -h   Put all harddrives on the system in standby mode just before halt or poweroff.
 
    -p   When halting the system, do a poweroff. This is the default when halt is called as poweroff.
 
DIAGNOSTICS
    If you  �   �  e not the superuser, you will get the message   �   �  ust be superuser � ? Users logged in locally on the console can call halt, reboot, and poweroff
    without supplying the root password, due to pam_console (8).
 
NOTES
    Under older sysvinit releases , reboot and halt should never be called directly. From release 2.74 on halt and reboot invoke shutdown(8) if the system is
    not in runlevel 0 or 6. This means that if halt or reboot cannot find out the current runlevel (for example, when /var/run/utmp hasn  �   �   been initialized
    correctly) shutdown will be called, which might not be what you want. Use the -f flag if you want to do a hard halt or reboot.
 
    The -h flag puts all harddisks in standby mode just before halt or poweroff. Right now this is only implemented for IDE drives. A side effect of putting
    the drive in standby mode is that the write cache on the disk is flushed. This is important for IDE drives, since the kernel doesn  �   �   flush the write-cache
    itself before poweroff.
 
    The halt program uses /proc/ide/hd* to find all IDE disk devices, which means that /proc needs to be mounted when halt or poweroff is called or the -h
    switch will do nothing.
 
AUTHOR
    Miquel van Smoorenburg, miquels@cistron.nl
 
SEE ALSO
    shutdown(8), init(8), pam_console(8)
 
                 Nov 6, 2001             HALT(8)
(END)

2: force reboot without calling the function of shutdown instruction

 [root@DB-Server ~]# reboot -f

3: turn off network Settings and restart the system

[root@DB-Server ~]# reboot -i
 
Broadcast message from root (pts/1) (Mon Jul 28 11:31:28 2014):
 
The system is going down for reboot NOW!

4: save the data and restart the system

[root@DB-Server ~]# reboot -n
 
Broadcast message from root (pts/1) (Mon Jul 28 11:33:57 2014):
 
The system is going down for reboot NOW!

5: the data is not written to the record file /var/tmp/wtmp when restarted

[root@DB-Server ~]# reboot -d
 
Broadcast message from root (pts/2) (Mon Jul 28 11:23:26 2014):
 
The system is going down for reboot NOW!