How to fix update-grub command not found on Linux

Prerequisites

sudo dnf install shim os-prober efibootmgr grub2 grub2-efi

Method 1: Use grub2-mkconfig to update grub

sudo grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg

Method 2: Create update-grub command

1. Create update-grub

cd
sudo vim /usr/sbin/update-grub

2. Edit update-grub

#!/bin/sh
set -e
sudo grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg "$@"

3. Set permissions

sudo chown root:root /usr/sbin/update-grub
sudo chmod 777 /usr/sbin/update-grub

4. Run command

update-grub