Steps to repair grub.cfg file corruption in Linux system

[root@node1 grub2]# ls
device.map fonts grub.cfg grubenv i386-pc
[root@node1 grub2]# pwd
/boot/grub2
[root@node1 grub2]# 

grub is a program that boots the operating system. It will boot the kernel according to its own configuration file. After the kernel is loaded into the memory,
The kernel will find the driver corresponding to the file system used by the root partition according to the configuration in the grub configuration file, and mount the root partition through the driver corresponding to the root partition file system, thereby achieving the purpose of starting the operating system.

1. Load MBR into memory, MBR = 512 bytes = boot program (446 bytes) + 64 bytes (partition table) + 2 bytes 2. BIOS loads the grub boot program, and system control is handed over to the boot program.
3. The boot program loads the configuration file /boot/grub2/grub.cfg, tells the partition where the /boot directory and the kernel file are located, and loads the kernel and initramfs and puts them into memory.
initramfs contains the kernel modules and initialization scripts necessary for the hardware to boot.
4. The kernel initializes itself, and the kernel finds the drivers for all the hardware in initramfs and initializes the hardware.
5./sbin/init in initramfs is started as a process with pid 1 and linked to systemd.
6. The kernel switches root from initramfs to the real root.
7. Start the first program systemd