CentOS7 fixes GRUB boot failure

GRUB is the default boot process used by most Linux systems, and you can choose to enter a different operating system (if any) through the boot menu. When the configuration file / boot/grub/grub.conf is missing, or the critical configuration is wrong, or is damaged, the further system startup process cannot be completed.

First, the failure phenomenon:

System boot stagnates, displaying the "grub >" prompt

Fault simulation:

Step 1: let's go to the / boot directory and find the file grub2.

Step 2: delete the grub.cfg (startup configuration file) from the grub2 file so that the system will not boot properly.

Step 3: restart the system and the failure interface occurs.

Second, the cause of the failure:

1. The GRUB bootstrap program in MBR is damaged.

2. Missing grub.conf file and incorrect boot configuration

Third, the steps to resolve:

Step 1: boot the first aid mode and load the system image:

Restart the system. When the boot screen appears, quickly press the esc key to boot out the first aid mode and select the CD- ROM Drive option.

Select the second option to enter the first aid system command mode

Step 2: re-establish the loaded sda partition (command: grub2-install / dev/sda)

Rebuild and build the grub menu configuration file (command: grub2-mkconfig-o / boot/grub2/grub.cfg)

Step 3: exit the bash environment

Command: exit

Step 4: restart

Command: reboot