Boot entry in ISO image?

Question

linux

Colleagues, good afternoon. Tell me which way to dig. The situation is the following. There is a bootable ISO image with one Linux distro. It is ISO and not the flash drive on which the ISO was recorded, because. I mount it in virtualbox. I needed to put a couple of my scripts into this image. I did this:
1) With the help of dd I pulled out the files from there
2) I put my scripts in the folder I needed
3) With the help of dd I recorded the iso again
The problem is that now my iso is not loaded, and I can’t understand why. I tried to compare in a hex editor, the first 2000 bytes really differ there, cloned again dd these bytes into my image, but there is no result. How to make my image bootable again? Perhaps you should study the iso file format that can be loaded, but again I don’t know where to start looking.

Answer 1

What does "did write iso with dd" mean? You can't just poke around in iso9660. It is necessary to mount (via loop device), get the files, make changes, assemble back.
In order for the disk to remain bootable, you need to understand what kind of bootloader it is (probably isolinux?) And rebuild the iso with this in mind (for example, for isolinux see here: https://wiki.syslinux.org/wiki/index.php?title=ISOLINUX ).

Answer 2

When burning ISO - you need to specify which file is bootable there.