Fast Operating System Switch for BerryBoot

BerryBoot is a bootloader for Raspberry Pi, allowing multiple operating system images to be placed on a single microSD card. It displays a menu upon system boot, so that the user can choose which OS to load.

I use a Raspberry Pi 3 as my primary desktop computer. It loads Ubuntu Mate 16.04 by default, in which I can code, read, and write dissertation. The same computer is also equipped with RetroPie, as my gaming machine playing FreeDoom.

One problem I'm frequently facing is: in order to switch from work mode to game mode, I must reboot the machine. Shutting down Ubuntu Mate can take as little as 10 seconds, or as much as 3 minutes, depending on luck. I hate to stay with the machine while it's rebooting, but if I walk away, I may miss the 10-second window in which I should select RetroPie from the BerryBoot menu, before it loads the default, Ubuntu Mate, automatically.

A less known feature of BerryBoot is its runonce file. You may instruct BerryBoot to load a specific image at next boot by writing the image name to data/runonce file in BerryBoot partition. This works particularly well if the Raspberry Pi is headless and does not have a keyboard, but it requires 5 steps and requires typing the full image name in the runonce file.

To simplify this process and quickly switch to another operating system in BerryBoot, I wrote a little script:


if [[ -z $WANTOS ]]; then
  echo Usage: ./ osname
  exit 2

gvfs-mount -d /dev/mmcblk0p2
cd /media/$(whoami)/berryboot/images
IMGNAME=$(ls *.img* | grep -i $WANTOS | head -1)

if [[ -z $IMGNAME ]]; then
  echo OS not found. Available images:
  ls *.img*
  gvfs-mount -u /media/$(whoami)/berryboot
  exit 3

echo $IMGNAME | sudo tee ../data/runonce

echo -n 'Rebooting into '$IMGNAME' '
for I in $(seq 5); do sleep 1; echo -n .; done

gvfs-mount -u /media/$(whoami)/berryboot
sudo shutdown -r now

This script accepts a single argument, which can be any substring of the desired OS image name. It mounts the berryboot partition in order to find the full image name, writes the runonce file, and triggers a reboot.

I use gvfs-mount instead of mount, so that I can delay sudo until after the full image name is determined, and therefore a prompt for entering password is a reminder that the system is about to be rebooted. The script also displays a "progress" of five dots, giving the user a final chance to cancel the reboot by pressing CTRL+C if the chosen OS is wrong.


OS image not found

reboot into another OS