Let grub re-scan disks?

Question

I placed a entry like this in grub4dos,

rootnoverify (hd1)
chainloader +1
boot

But sometimes when I plug in my USB key too late, grub will not detect this usb key, is there anyway to let grub re-scan disk list?

I need to know for both grub0.9X and grub1.9X

Answer 1

Run the following command as root:

update-grub