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I placed a entry like this in grub4dos,

rootnoverify (hd1)
chainloader +1

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

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2 Answers 2

Run the following command as root:


EDIT: This is an Ubuntu specific command. To do this on another distribution, just run grub-mkconfig -o /boot/grub/grub.cfg

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From what I've seen, I don't believe this is possible. I was in a similar situation where I setup a GRUB entry to boot from a USB. If I didn't have a USB stick in before startup, the boot option fails. If I boot with the USB stick already connected, the option would boot from the USB.

Using GRUB 0.97, I've scanned the manual and tried many commands but I didn't see anything related to re-initializing the disks.

I see many hints in the manual that GRUB relies on the BIOS (if not entirely). When playing with boot options from the BIOS, it's in the same situation where if I don't have the USB stick plugged in before BIOS starts, it will never be listed as a bootable option (using AMI, Aptio). Maybe this is a BIOS limitation, a limitation of both or I could just strayed on a tangent.

I thought this was going to be an issue for me, but then I wondered what was easier: having someone toggle to the GRUB command mode and reinitialize disks or just CTRL-ALT-DEL'ing...

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