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What is a ISO-Hybrid image ?

Bootable ISO image files can not usually be transferred to a USB storage device to create a bootable USB stick.

ISO 9660 filesystems created by the mkisofs command as described in the ISOLINUX article will boot via BIOS firmware, but only from optical media like CD, DVD, or BD.

However, special types of ISO files called hybrid ISOs can be flashed to create a bootable usb device.

We can convert standard ISO files into hybrid ISOs with the isohybrid command.

The command is available in your yum or apt-get repository as syslinux-utils.

The isohybrid feature enhances such filesystems by a Master Boot Record (MBR) for booting via BIOS from disk storage devices like USB flash drives.

ISOLINUX provides two alternative programs to apply this feature on image files or block devices with ISO 9660 filesystems:

This alternative program command will make your ISO image file bootable for a usb drive:

'''# isohybrid image.iso'''

If the ISO 9660 image includes a UEFI bootloader capable of booting optical media in UEFI mode,

then the isohybrid command can also achieve an equivalent result for UEFI systems just as described for BIOS ones.

The additional isohybrid feature for UEFI adds a partition to the MBR partition table pointing to the same file in the ISO 9660 filesystem as does the El Torito catalog entry for EFI.

This file contains a FAT filesystem with boot equipment from which the UEFI firmware will be able to start the desired operating system.

Furthermore, isohybrid for UEFI creates a GUID Partition Table (GPT) with a partition pointing to that file.

Step 1 - ISO download

Download the newest puppy linux iso image from here

https://puppylinux.com/index.html

Step 2 - Install utility

Install isohybrid utility programm that is part of syslinux-utils

Step 3 - Convert ISO to ISO-Hybrid

Convert the ISO image into a ISO-Hybrid image with this command.

In our example we downloaded the fossapup64-9.5.iso image and

we convert it to a iso hybrid image as follow:

'''# isohybrid fossapup64-9.5.iso'''

Step 4 - Flash Hybrid ISO Image

Burn the ISO-Hybrid image either to a USB Drive or CD-ROM using your favorit tool.