As the title says I would like to know how the guys at Canonical generate the release ISO file for this version of the Ubuntu OS. Above all I'm interested in how they create the isohybrid image.
How can I replicate the process starting from the files contained in the ISO file? Cleary the derived image should be bootable in EFI/UEFI based systems.
Also, I would like to know why, when I try to display the partition contents of the ISO image with fdisk, one of the two partitions (the first one) its type is "Empty" when it contains all the Ubuntu files for the install media, isn't it a ISO9660 like partition?
I would also be interested in replicating the partition structure of the ISO file on a USB drive.
Could someone point me in the right direction?
Are the answers to my questions documented somewhere? Or at least some?
Thank you very much!