Linux boot failure handling-Beginner

1. MBR (boot grub) lost (dd If=/dev/zero OF=/DEV/SDA bs=446 count=1) Erase MBR
   

   1) Enter rescue mode

   2) Chroot/mnt/sysimage put the real root on the hook

   3) Start repairing grub and loading grub onto the hard drive. Grub2-install/dev/sda

   After the installation is complete, 2 exit will be restarted automatically.

   
   

DD IF=/DEV/SDA of=mbr bs=512 count=1 #备份MBR

DD IF=MBR OF=/DEV/SDA #恢复MBR

2. The bootloader configuration file is missing (/boot/grub2/grub.cfg)

Grub> set root=hd0,msdos1 grub> linux16/boot/vmlinuz-###### root=/dev/sda1 ro grub> initrd16/boot/initramf s-####### grub> Boot

# grub2-mkconfig >/boot/grub2/grub.cfg #用此命令生成新的引导配置文件

Over

3. Kernel and driver lost

In rescue mode, forcing the kernel to be reinstalled.

4. Root password is missing

1) On the Boot Menu page, press E to find linux16, remove the parameters from the RO, and add rd.break

2) Ctrl-x continue to start and then be interrupted

3) At this time the real root of the system is hung in a read-only manner under the/sysroot

4) Mount-o remount,rw/sysroot/re-mount as writable

5) chroot/sysroot/to hang the real roots back.

6) passwd command to change password

7) Touch/.autorelabel #打标签

Sync #硬盘同步

2 exit system will continue to start

Over

Linux boot failure handling-Beginner