Add 'ISO-Repack.md'

ISO-Repack.md

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+# 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/