I'm trying to figure out how to remove a file from a bootable ISO on Debian Buster. Problem is: all the answers I can find via Google (no doubt there's more that don't show and this'll instantly be duplicate of a question whose answer yet again breaks the bootability of the ISO) break the bootability. This is a DOS bootable ISO, and I need to delete a file on the root of the ISO. mkisofs is out of the question as it's got info in the MBR I need to preserve, and mkisofs seems to have 0 ways to preserve the MBR. I've also tried ISO Master, which also breaks it. Any ways to delete this file from the ISO without breaking everything?
Figured it out. Something like ISO Master would work, and you can copy over the old ISO's MBR by doing
dd if=<original file> of=<modified file> bs=2k count=20
This copies the first few sectors of the old ISO on top of the new one, replacing the generated MBR with the old one.