Q:

How to use GRUB from a USB drive to boot any OS that is on the HDD?

I got two operating systems on my laptop(Win 8.1 and Kali), but i updated from win 7 and deleted the boot record. To be honest i don't want Grub on my HDD, i like booting directly into windows. My idea was to install Grub on to a usb stick and load into kali whenever i need to or want to. Is that possible? I only found topics on booting all kind of OS's from usb but not from HDD.

A:

I finally found the best method for me to start Kali without reinstalling Grub to my HDD. For this i used unetbootin and SuperGrub(Download here)

First install unetbootin:

sudo apt-get install unetbootin

Then rename the supergrub .iso to .img (using .iso gave me booterrors) and start unetbootin. 
In unetbootin select the floppy method and load the renamed .img file. 
Select the USB drive and press OK.
Now use the stick to boot whatever OS is on your HDD.

I used the USB stick on my laptop and loaded into Supergrub and found every OS that is installed on the HDD. Worked great. This way i can keep windows as main OS and always boot directly into it and whenever i want to use Kali i just pop in my USB drive and use Supergrub.

