Ubuntu – Remaster / customize 16.04 live CD image and make USB bootable

I can make a live CD image from the original 16.04 ISO image following these instructions:

https://help.ubuntu.com/community/LiveCDCustomization

My "remastered" ISO boots fine using kvm.

When I use the original 16.04 source ISO in "startup disk creator", I get a bootable USB, of course.

However, when I use my remastered ISO with "startup disk creator", it does not result in a bootable USB (at least with the PC I'm trying to boot it with). I notice that the USB I get from my remastered ISO shows up as only (say) /dev/sdb, but a USB from the original ISO (same USB stick) shows up as: /dev/sdb, /dev/sdb1, /dev/sdb2

So, I'm guessing maybe this has something to do with UEFI. But how can I make a USB stick created from my remastered image bootable?

Best Answer

Run isohybrid(1), which will rewrite the ISO to make it USB bootable:

$ isohybrid customized_ubuntu.iso

Then you can use Startup disk creator, or some other tool, to write the image to a USB disk.

Startup disk creator (which lives in package usb-creator) simply ends up doing the equivalent of a dd, at least for ISO images (I didn't check what it does for .img files), and so is unrelated to this problem.