linux/ISO-Repack.md

Repack linux ISO

Commands expect to be in a root shell

Install needed tools

mkisofs xorriso isohybrid

Editing ISO image

Create workspace
mkdir /tmp/custom_iso
Mount image and extract it since it is read only

mount -t iso9660 -o loop ~/original.iso /mnt/`  
tar cf - /mnt/. | (cd /tmp/custom_iso; tar xfp -)

You can now modify the files for editing the bootloader config for example!

Back into an iso

Legacy only

Rebuild iso with mkisofs
mkisofs -o output.iso -b syslinux/isolinux.bin -c syslinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -J -R -V "Custom ISO" /tmp/custom_iso
Bless it with isohybrid
isohybrid output.iso

EFI and Legacy

Rebuild iso with mkisofs
mkisofs -o output.iso -b syslinux/isolinux.bin -J -R -l -c syslinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -eltorito-alt-boot -e boot/grub/efi.img -no-emul-boot -graft-points -V "Custom ISO" /tmp/custom_iso
Bless it with isohybrid
isohybrid --uefi output.iso

Sources

https://gist.github.com/AkdM/2cd3766236582ed0263920d42c359e0f
https://tuxfixer.com/mount-modify-edit-repack-create-uefi-iso-including-kickstart-file/