I want to make a .iso image of a bootable OS DVD, to use in VirutalBox.
Nautilus can make a .iso, but only of data files, it seems.
The .iso it created was not bootable.
What is available to make a bootable .iso from a bootable DVD?
You can use Brasero to copy a CD to an .iso; this is installed by default.
Select the option to copy a CD, select the CD drive as the source, and an image file as the target...
Or from inside Nautilus: go to "Computer", right-click on the CD drive, en select "Copy Disc...". (Or something like that, I'm using a local language system here.)
First up, you can give VMs access to the host's DVD drive in VBox, this is done where you would normally add an ISO as a drive.
If this doesn't suit you, try
That said, ripping an image of the ISO with ISO Master should take the boot sector intact, and you won't need to transfer it manually.