John Hawthorn

Reboot to Windows on a UEFI system

A watched PC never boots. proverb

I am the sort of person who needs to boil a kettle of water three or four times. I will turn it on, walk away, forget it until it’s cold, and repeat.

I dual boot my desktop computer between Linux and Windows (to play Overwatch). By default, the computer boots into Linux. To boot into windows I need to catch it while it’s displaying the boot menu which has a 3 second timeout. I am terrible at this.

Years ago, I blogged about changing the grub default with a script to reboot into windows. But I’m now using systemd-boot, a UEFI boot manager.

Fortunately, UEFI itself provides a solution. There’s a BootNext variable, which allows choosing a one-time boot entry.

First I list my boot entries using efibootmgr.

$ sudo efibootmgr BootCurrent: 0001 Timeout: 1 seconds BootOrder: 0001,0000,0002,0003,0004 Boot0000* Windows Boot Manager Boot0001* Linux Boot Manager Boot0002* Samsung SSD 850 EVO 500GB Boot0003* SanDisk SDSSDHP256G Boot0004* SAMSUNG SSD 830 Series

Seeing that Windows is Boot0000 I can make the following reboot-windows script

#!/bin/sh efibootmgr -n 0000 # Windows is Boot0000 reboot # or maybe suspend to disk

Easy! Running reboot-windows will boot me into Windows, bypassing the systemd-boot bootloader entirely. Rebooting from windows will take me back to Linux (through systemd-boot again).