linux关闭系统是有序终止所有进程，断电前执行重要的内务整理工作，以下五个命令可以完成这项工作：
halt
reboot
poweroff
shutdow
init

reboot

reboot [OPTIONS...] [ARG]

Reboot the system.

     --help      Show this help
     --halt      Halt the machine
  -p --poweroff  Switch off the machine
     --reboot    Reboot the machine
  -f --force     Force immediate halt/power-off/reboot
  -w --wtmp-only Don't halt/power-off/reboot, just write wtmp record
  -d --no-wtmp   Don't write wtmp record
     --no-wall   Don't send wall message before halt/power-off/reboot

reboot -p #调用 halt 或 poweroff 命令，切断设备电源。
reboot -d #仅重启，不写/var/log/wtmp记录

poweroff

poweroff [OPTIONS...]
Power off the system.

     --help      Show this help
     --halt      Halt the machine
  -p --poweroff  Switch off the machine
     --reboot    Reboot the machine
  -f --force     Force immediate halt/power-off/reboot
  -w --wtmp-only Don't halt/power-off/reboot, just write wtmp record
  -d --no-wtmp   Don't write wtmp record
     --no-wall   Don't send wall message before halt/power-off/reboot

例如：

poweroff -w #不关闭主机，仅在/var/log/wtmp中写入记录
poweroff -f #强制关机
poweroff -d #仅关机，不写/var/log/wtmp记录

shutdown

shutdown [OPTIONS...] [TIME] [WALL...]

Shut down the system.

     --help      Show this help
  -H --halt      Halt the machine
  -P --poweroff  Power-off the machine
  -r --reboot    Reboot the machine
  -h             Equivalent to --poweroff, overridden by --halt
  -k             Don't halt/power-off/reboot, just send warnings
     --no-wall   Don't send wall message before halt/power-off/reboot
  -c             Cancel a pending shutdown

例如：

shutdown -r -t 10  #10s后重启系统
shutdown -c #取消之前的showdown操作
shutdown -h now #立即关机
shutdown -h 17:30 #停止系统的服务，在17：30关机
[root@09385 ~]# shutdown -k 10:00  #通知在线用户10:00将要关机
Shutdown scheduled for 日 2022-08-07 10:00:00 CST, use 'shutdown -c' to cancel.

halt

halt [OPTIONS...]

Halt the system.

     --help      Show this help
     --halt      Halt the machine
  -p --poweroff  Switch off the machine
     --reboot    Reboot the machine
  -f --force     Force immediate halt/power-off/reboot
  -w --wtmp-only Don't halt/power-off/reboot, just write wtmp record
  -d --no-wtmp   Don't write wtmp record
     --no-wall   Don't send wall message before halt/power-off/reboot

注：halt用法参照poweroff或reboot用法

init

#init 0 - 停机（千万不能把initdefault 设置为0 ）

#init 1 - 单用户模式，只root用户进行维护

#init 2 - 多用户，不能使用NFS(Net File System) 不联网

#init 3 - 完全多用户模式(标准的运行级)

#init 4 - 安全模式

#init 5 - X11 （xwindow) 图形化界面模式

#init 6 - 重新启动 （千万不要把initdefault 设置为6 ）

wtmp文件内容查看

在介绍前面的命令时，提到关闭系统操作会不会记录在/var/log/wtmp中（wtmp中还会记录用户登录也操作），wtmp是二进制文件，目的是防止人为恶意篡改，那么如果查看这个文件中的内容呢，使用last命令看查看其中的记录

[root@09385 ~]# last --help
last: invalid option -- '-'
Usage: last [-num | -n num] [-f file] [-t YYYYMMDDHHMMSS] [-R] [-adioxFw] [username..] [tty..]

例如：

[root@09385 ~]# last
root     pts/1        172.17.84.169    Sat Aug  6 21:42   still logged in   
root     pts/0        172.17.84.169    Sat Aug  6 21:42   still logged in   
root     pts/1        172.17.84.169    Sat Aug  6 21:25 - 21:35  (00:10)    
root     pts/0        172.17.84.169    Sat Aug  6 21:25 - 21:35  (00:10)    
reboot   system boot  5.10.0-202204291 Sun Aug  7 05:05 - 21:42  (-7:-23)   
root     pts/1        172.17.84.169    Sat Aug  6 20:59 - crash  (08:06)    
root     pts/0        172.17.84.169    Sat Aug  6 20:59 - crash  (08:06)    
reboot   system boot  5.10.0-202204291 Sun Aug  7 01:15 - 21:42  (-3:-33)   
root     pts/1        172.17.84.169    Sat Aug  6 17:13 - down   (00:00)    
root     pts/0        172.17.84.169    Sat Aug  6 17:13 - down   (00:00)    
root     pts/1        172.17.84.169    Fri Aug  5 14:15 - 14:25  (00:10)    
root     pts/0        172.17.84.169    Fri Aug  5 14:15 - 14:25  (00:10)    
root     pts/1        172.17.85.72     Fri Aug  5 13:39 - 13:44  (00:04)    
root     pts/0        172.17.85.72     Fri Aug  5 13:39 - 13:44  (00:04)
[root@09385 ~]#last root
root     pts/1        172.17.84.169    Sat Aug  6 21:42   still logged in   
root     pts/0        172.17.84.169    Sat Aug  6 21:42   still logged in   
root     pts/1        172.17.84.169    Sat Aug  6 21:25 - 21:35  (00:10)    
root     pts/0        172.17.84.169    Sat Aug  6 21:25 - 21:35  (00:10)    
root     pts/1        172.17.84.169    Sat Aug  6 20:59 - crash  (08:06)    
root     pts/0        172.17.84.169    Sat Aug  6 20:59 - crash  (08:06)    
root     pts/1        172.17.84.169    Sat Aug  6 17:13 - down   (00:00)    
root     pts/0        172.17.84.169    Sat Aug  6 17:13 - down   (00:00)    
root     pts/1        172.17.84.169    Fri Aug  5 14:15 - 14:25  (00:10)    
root     pts/0        172.17.84.169    Fri Aug  5 14:15 - 14:25  (00:10)    
root     pts/1        172.17.85.72     Fri Aug  5 13:39 - 13:44  (00:04)    
root     pts/0        172.17.85.72     Fri Aug  5 13:39 - 13:44  (00:04)

如果你不想这些记录被别人查到怎么整？

清空登录记录

echo 1 >/var/log/wtmp

清空操作记录

history -c