From VirtualBox VM (.vdi file) to a USB bootable ISO image

Question

I have set up a virtual machine with Xubuntu Linux in VirtualBox.

The disk is 4.5 GB a .vdi file.

How can I make an IMG or ISO file from this, such that I can then write it into a bootable USB flash drive,

• either with Rufus disk imager software (on Windows)

• or with dd if=myvm.img of=/dev/sdc

?

TL;DR: I'm searching for a convert-vmdisk myvm.vdi myvm-bootable.img tool.

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I've already tried answers from Is it possible to convert virtual machines to physical environments? and especially

VBoxManage internalcommands converttoraw file.vdi output.img

but then after writing this .img to a USB flash drive (with Rufus), the PC won't boot on this USB flash drive.

Linked topic: https://forums.virtualbox.org/viewtopic.php?t=40124

Answer 1

After a few number of attempts, finally this works:

VBoxManage internalcommands converttoraw file.vdi output.img

Then Rufus to write it to a USB flash drive or external USB HDD.

Initially, I couldn't boot this device on computer startup.

Reason: my BIOS was set up on "UEFI only". I switched this parameter to "Both (UEFI and Legacy)", and "Legacy first". Then it works!