[Solution] Grub Dual Boot without Keyboard

[AtomicAntimatter]

Problem
Currently, a gamepad/joystick cannot be used to select the OS to boot during startup. Plugging in a keyboard just to change the OS is not an ideal solution.

If you have a spare USB drive laying around, you may use it as an OS key. The flash drive must simply have at least 15mb, the rest of the space you will be able to use.

Plugging/Unplugging a small flash drive from a dual-boot steam box is more convenient.

Solution
Put Grub on USB with default OS selected to [Windows or Linux]
Have Grub on Primary HDD with default OS selected to the opposite.
Set boot order in BIOS to start with USB, then HDD

Steps

1. From the SteamOS, launch to desktop
   
2. Plug in the USB drive and open a terminal
   
3. Figure out the mounted location
   To list all your drives:

    df 

   Mine was located at:

    /dev/sdc 

   Mine was mounted at:

    /media/usb0 

   I will be using these locations below. Remember to use your own locations.
   Note: sdc1 is the partition, sdc is the drive
   
4. Wipe the drive by making a new partition
   First unmount the drive:

    sudo umount /media/usb0 

    sudo cfdisk /dev/sdc 

   Make sure this is the correct drive you're messing with because you will now erase it.
   Delete the partition.
   Make a new one but set the size to be 15mb smaller than the maximum and position the partition at the end of the drive.
   Set the type to 0B, which should be 'W95 FAT32'
   Write and exit.
   Next convert the partition to vfat:

    sudo mkfs -t vfat /dev/sdc1 

5. Put grub onto the drive
   First mount the drive:

    sudo mount /dev/sdc /media/usb0 

    sudo grub-install --no-floppy --root-directory=/media/usb0 /dev/sdc 

6. Edit grub for flash drive
   

    sudo nano /etc/default/grub 

   Set GRUB_DEFAULT= the index of the OS to boot with the drive inserted.
   The first listed OS on boot is index 0, second is 1...etc
   This would be GRUB_DEFAULT=2 for me to boot up Windows.
   [Optional] Set GRUB_TIMEOUT=0 to skip the menu at boot
   Once done, exit and update to drive:

    sudo grub-mkconfig -o /media/usb0/boot/grub/grub.cfg 

7. Edit grub for HDD
   

    sudo nano /etc/default/grub 

   Set GRUB_DEFAULT= the index of the OS to boot up without the drive inserted.
   This would be GRUB_DEFAULT=0 for me to boot up SteamOS.
   [Optional] Set GRUB_TIMEOUT=0 to skip show the grub menu at boot
   Once done, exit and update to HDD:

    sudo update-grub 

8. Set boot order in BIOS to start with USB, then HDD
   
   You are all set. Test it out, if there are any issues or ideas feel free post. I will try my best to help out. I'll look into making a shell script for this if there is interest.

[testman]

I think your implementation of "OS key" is quite good idea.
I just cannot see what other OS than SteamOS you could use without keyboard?
Ssme other Linux with XBMC or similar UI?