Reboot to Linux From Windows

RebootLinux.bat

:: _Sigh_ Windows dumbness...
powershell .\RebootLinux.ps1

RebootLinux.ps1

# Figure this out with 'GET-CimInstance -query "SELECT * from Win32_DiskDrive"'
$LinuxRootDisk = "\\.\PHYSICALDRIVE0"
$LinuxRootPart = 2

# This needs to be run as admin, thus the funky Start-Process stuff.
$cmd = "wsl --mount $LinuxRootDisk -p $LinuxRootPart --bare"
Start-Process -Verb RunAs cmd.exe -Args '/c', $cmd

# Call the WSL script to set all the necessary GRUB stuff.
bash -c "sudo /home/joshua/RebootLinux.sh"

# Reboot the system
shutdown /r /t 5 /d p:0:0 /c "Rebooting to a much better OS :)"

pause

RebootLinux.sh

#!/usr/bin/env bash
# /home/USER/RebootLinux.sh

# UUID of Linux partition with GRUB installation at /boot/grub.
ROOT_UUID="UUID"
# Mount point within WSL.
MOUNT_POINT="/mnt/root"
# Desired GRUB default boot entry on reboot.
BOOT_ENTRY="0"

if [ "$#" -gt 1 ]; then
    printf "%s" "Usage: $0 [ENTRY_NUM]"
    exit 1
elif [ "$#" -eq 1 ]; then
    BOOT_ENTRY="$1"
fi

if [[ $(/usr/bin/id -u) -ne 0 ]]; then
    printf "%s\n" "Rerun as root please."
    exit 1
fi

if [ ! -d "$MOUNT_POINT" ]; then
    printf "%s\n" "Mount point doesn't exist!"
    exit 1
fi

if ! mount -U "$ROOT_UUID" "$MOUNT_POINT"; then
    printf "%s\n" "Failed to mount root partition"
    exit 1
fi

if ! grub-reboot --boot-directory="$MOUNT_POINT/boot" "$BOOT_ENTRY"; then
    printf "%s\n" "Failed to call grub-reboot"
    exit 1
fi

umount "$MOUNT_POINT"

printf "%s\n" "    .--."
printf "%s\n" "   |o_o |"
printf "%s\n" "   |:_/ |"
printf "%s\n" "  //   \ \\"
printf "%s\n" " (|     | )"
printf "%s\n" "/'|_   _/'\\"
printf "%s\n" "\___)=(___/"

printf "%s\n" "Done on the WSL side. See you in Linux friendo!"

This set of scripts is used to quickly reboot from Windows to Linux without having to select the other OS within the Grub menu. This is done by mounting the root partition in WSL, then using grub-reboot to set the necessary boot variables.

The bash and powershell scripts do all the heavy lifting. The batch script is just a convenient way to call it and reboot the system without having to manually open a powershell window. The fact that in 2022 you can double-click on an .exe, .bat, or .vbs script and run it just fine, but you can't with powerShell is mind boggling to me.