Reboot to Windows Once from Linux

On a dual-boot machine, you may occasionally want to reboot into Windows from Linux for a specific task—such as using a Windows-only application—and then return to Linux afterward. While GRUB allows you to choose which OS to boot, it is more convenient to have a one-time reboot option that boots directly into Windows, then automatically returns to Linux as the default on subsequent boots. This can be accomplished using efibootmgr to set the next boot entry to Windows.

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sudo efibootmgr -n <WindowsBootEntryNumber>

Here, <WindowsBootEntryNumber> is the boot entry number for Windows, which you can find by running efibootmgr without any arguments. The output will list all boot entries and their numbers. For example:

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BootCurrent: 0005
Timeout: 2 seconds
BootOrder: 0005,0004,2001,2002,2003
Boot0001* EFI PXE 0 for IPv4
Boot0002* EFI PXE 0 for IPv6
Boot0004* Windows Boot Manager
Boot0005* GRUB

To set the next boot to Windows, run:

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efibootmgr -n 0004

After executing this command, reboot your machine. It will boot into Windows for that session. On the next reboot, it will default back to Linux.

Creating a Shortcut Script

To streamline this process, create a simple script at /usr/local/bin/reboot2win:

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#!/usr/bin/env bash
# reboot2win: A script to reboot into Windows once
logger -t reboot2win "reboot2win executed by ${SUDO_USER:-$USER}"
# privileged command(s) below:
/usr/bin/efibootmgr -n 0004 && /usr/bin/systemctl reboot

Make it executable and set ownership to root for security:

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sudo chmod +x /usr/local/bin/reboot2win && sudo chown root:root /usr/local/bin/reboot2win

Now you can run sudo reboot2win to reboot into Windows once.

Make It Even Easier with Polkit

To avoid typing sudo every time, you can create a polkit rule to allow your user to run the script without a password prompt. Create a file at /etc/polkit-1/rules.d/50-reboot2win.rules with the following content:

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polkit.addRule(function (action, subject) {
  if (action.id == "org.freedesktop.policykit.exec") {
    var program = action.lookup("program");
    if (
      program == "/usr/local/bin/reboot2win" &&
      subject.isInGroup("wheel") &&
      subject.local &&
      subject.active
    ) {
      return polkit.Result.YES;
    }
  }
  return polkit.Result.NOT_HANDLED;
});

This rule allows users in the wheel group to execute the reboot2win script without a password prompt. Adjust the group name if your user belongs to a different group.

To apply the rule, restart the polkit service:

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sudo systemctl restart polkit

Now you can simply run the following command without sudo:

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pkexec /usr/local/bin/reboot2win

Finally, you can add an alias or a desktop shortcut for easier access. Also, to avoid accidentally running the command, you can use a confirmation prompt dialog such as kdialog or zenity. For example, using kdialog:

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bash -lc 'kdialog --yesno "Are you sure you want to reboot the system?"' && pkexec /usr/local/bin/reboot2win

This will show a confirmation dialog before executing the reboot command.