USB boot option does NOT appear in the GRUB menu while booting from Ubuntu 20.04
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GRUB does not "search for" bootable devices: it acts on its configuration files, which are usually auto-generated. Yes, you can create a menu entry which corresponds to anything.
If you want to "boot from a USB device," then you should probably arrange for BIOS to do it: in this case, GRUB will never receive control at all.
^ This!
But that will require a properly created USB boot medium. Instructions on the distro's website.
Because this:
tells me that this is likely NOT a bootable Ubuntu USB.
If you indeed really want to boot the .ISO directly from GRUB, this is also possible but more difficult, and I don't think that's what you actually want.
Please see the screenshot.
Also, this is what I get when I reboot and press F12
I think you are pressing the wrong f-key. You are going into bios setup, not the bios boot-menu.
Maybe esc f1 or f2 key to get to bios boot menu.
What is make and model of computer?
(tick marked in this order)
ubuntu
UEFI SSD 128GB <a long number>
..
There should also be an option to select the bios boot menu which would display all the bootable devices the system sees.
Note that the drive (SSD above) shows as UEFI and I do not believe that ubuntu 16.04 is capable of booting in uefi mode. This means that before the USB could be used to boot, the bios must be set to allow booting in legacy mode (often shown in the bios as CSM or something similar). If the bios is set to boot uefi only then it will never see a legacy boot device as bootable.
Hold on. /dev/sdb1 (what is the iso) is the FIRST partition of /dev/sdb, not the whole drive. The whole drive should identify as an iso, meaning /dev/sdb not /dev/sdb1.
The computer from which I type and the one having problems are different, hence.
The problem computer is a 64bit uefi system that you are attempting to boot an outdated non-uefi 32bit ubuntu iso.
To boot the usb, legacy mode will need to be enabled in the bios-setup, then press the correct key to get the bios boot-menu at power-on.
Update-grub will not add a menu entry for a removable usb. To boot the usb from the installed ubuntu grub menu you will need to manually add a menu-entry to boot the kernel/initrd.img of the usb. You won't be able to chainload the usb.
Last edited by colorpurple21859; 01-16-2023 at 11:34 AM.
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