Build Custom ISO
cp ubuntu-preseed.seed custom-iso/preseed/ubuntu-preseed.seed
cp -av post-install custom-iso/
Note
Ensure that the modified boot menus have been copied to the ISO image if not modified directly.
Take the existing multi-boot (EFI/non-EFI) image from the iso and reuse it to create the new ISO image:
sudo dd if=<ubuntu>.iso bs=512 count=1 of=custom-iso/isolinux/isohdpfx.bin
cd custom-iso
md5sum $(find -type f) > md5sum.txt
cd custom-iso
sudo xorriso -as mkisofs -isohybrid-mbr isolinux/isohdpfx.bin -c isolinux/boot.cat -b isolinux/isolinux.bin -no-emul-boot -boot-load-size 4 -boot-info-table -eltorito-alt-boot -e boot/grub/efi.img -no-emul-boot -isohybrid-gpt-basdat -o ../custom-ubuntu.iso .
cd ..
sha512sum custom-ubuntu.iso > custom-ubuntu.sha512sum
sha512sum -c custom-ubuntu.sha512sum
fdisk -l custom-ubuntu.iso
Device Boot Start End Sectors Size Id Type
custom-ubuntu.iso1 * 0 1763327 1763328 861M 0 Empty
custom-ubuntu.iso2 4028 8763 4736 2.3M ef EFI (FAT-12/16/32)
Note
iso1
and iso2
presence will confirm there is an EFI and non-EFI ISO in
the image.