Time-Saving OS Rescue Commands

Only once machinery has broken down do we become aware of its complexity.

Booting LFS

set root=(hd0,1)
set prefix=(hd0,1)/grub
normal

Booting Gentoo

linux (hd0,gpt2)/vmlinuz-<version> root=/dev/vda3
initrd (hd0,gpt2)/initramfs-<version>.img
set root=(hd0,gpt3)
boot

Useful Kernel Parameters

pci=nomsi

Creating a New EFI Entry (Useful After CMOS Reset)

efibootmgr -c -d /dev/sda -L Arch -l \\EFI\\arch\\grub.efi

No Internet Connection in Chroot Environment

Copy host system's /etc/resolv.conf into the chroot environment

Windows from Grub (BIOS)

set prefix=(hd0,msdos1)/boot/grub
insmod normal
normal

Windows from Grub (UEFI)

chainloader +1 #Should return "invalid efi path"
ls (hd0,gpt1)/ #Should list "EFI" dir
chainloader (hd0,gpt1)/EFI/Microsoft/bootmgfw.efi
boot

Windows Environment Variable Location

User Variables:

HKEY_CURRENT_USER\Environment

System Variables:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment

Note: restart explorer.exe to see changes.

Windows BCD Problems

bootrec /?
bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcd
boot

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