因为默认debian 10下没有PATH=$PATH:/sbin的环境变量
而poweroff以及reboot等命令均放置在/sbin下面，所以直接执行会提示command not found
解决办法很简单，几条命令即可
以root用户登录
cd ~ nano .bashrc 在最底下的位置 加入一行 PATH=$PATH:/sbin ctrl+x 保存退出
root@debian:~# cat .bashrc
# ~/.bashrc: executed by bash(1) for non-login shells.
# Note: PS1 and umask are already set in /etc/profile. You should not
# need this unless you want different defaults for root.
# PS1='${debian_chroot:+($debian_chroot)}\h:\w\$ '
# umask 022
# You may uncomment the following lines if you want `ls' to be colorized:
# export LS_OPTIONS='--color=auto'
# eval "`dircolors`"
# alias ls='ls $LS_OPTIONS'
# alias ll='ls $LS_OPTIONS -l'
# alias l='ls $LS_OPTIONS -lA'
#
# Some more alias to avoid making mistakes:
# alias rm='rm -i'
# alias cp='cp -i'
# alias mv='mv -i'
PATH=$PATH:/sbin