了解一下centos7的运行级别：
# ll /usr/lib/systemd/system/runlevel*target lrwxrwxrwx. 1 root root 15 Nov 30 02:38 /usr/lib/systemd/system/runlevel0.target -> poweroff.target lrwxrwxrwx. 1 root root 13 Nov 30 02:38 /usr/lib/systemd/system/runlevel1.target -> rescue.target lrwxrwxrwx. 1 root root 17 Nov 30 02:38 /usr/lib/systemd/system/runlevel2.target -> multi-user.target lrwxrwxrwx. 1 root root 17 Nov 30 02:38 /usr/lib/systemd/system/runlevel3.target -> multi-user.target lrwxrwxrwx. 1 root root 17 Nov 30 02:38 /usr/lib/systemd/system/runlevel4.target -> multi-user.target lrwxrwxrwx. 1 root root 16 Nov 30 02:38 /usr/lib/systemd/system/runlevel5.target -> graphical.target lrwxrwxrwx. 1 root root 13 Nov 30 02:38 /usr/lib/systemd/system/runlevel6.target -> reboot.target![]
这次使用的就是rescue target,救援模式
挂载好你的光驱或者U盘系统盘
使用光盘或者U盘引导
根据提示按回车，继续
根据提示，你的系统根目录是/mnt/sysimage
1712/01/dc531416a657f13275062f8304159ef8.png?x-oss-process=image/watermark,size_16,text_QDUxQ1RP5Y2a5a6i,color_FFFFFF,t_100,g_se,x_10,y_10,shadow_90,type_ZmFuZ3poZW5naGVpdGk=)
exit reboot
救援模式能做的事情很多
原文链接：https://www.f2er.com/centos/375138.html