Alright thanks. Well if you know of any good resources for xorriso particularly with the -b (boot) flag I'd like to read them.
Google has been mostly serving me 15 year old SO posts that aren't relevant to modern Linux anymore.
I found Gentoo more helpful than LFS because with LFS you compile about 80 packages from source one at a time but you don't learn too much about the packages.
LFS gave me much more awareness of what packages actually come with a Linux install but Gentoo taught me more about configuring and booting a Linux system.
Although I'd definitely recommend both to anyone wanting to learn. I'd do Gentoo first then LFS.
Edit: LFS is also a masterclass in cross compiling so if that's something you're curious about LFS is the way to go.
So eggs is great for Debian with my Gnome stuff.
As for xorriso I have a LFS dir that very much resembles a Linux root dir (without a DE or any distro specific software) and I can chroot into it mounting /dev, /sys, /run, /proc from my host system.
I would like to compress that LFS dir into an iso combined with a boot loader.
That LFS dir is on a separate partition and does have a boot loader installed on that partition's hard drive. But I'd rather boot it in a virtual machine and I didn't want to give the vm raw hard drive access.
I hope that helps but I'm happy to answer more questions.
Booting into a live CD isn't a hard requirement because I can probably just use eggs after I get it to boot in a vm.
Edit: also thanks for the insight about xorriso I had real trouble finding much info about the differences between the three.
Edit 2: I'm going to run LFS on the exact same hardware it compiled on so I can probably use grub installed on my host system.
That said I did try using grub-mkimage on my host system and when passing that iso into mkisofs -b I still couldn't get a boot. (No bootable medium found.)
Going to try the penguins-eggs method you posted. I would love to be able to turn a virtual box environment into an installable medium to make my own version of debian with all my gnome tweaks.
I would also love a solution that doesn't require booting into the OS first. So that I can take a root dir and turn it into a bootable iso. I tried a bunch of old tutorials for making a boot.iso and linking it into mkisofs with -b but it never worked.
I am willing to learn/use any free tooling. Not picky at all.
I've been struggling to make a bootable iso. I did Linux from scratch and I wanted to boot it in virtual box. I found a sparse amount of info about mkisofs/genisofimage but I couldn't actually get a successful boot after following a few tutorials.
I have to imagine there are more modern tools for something like this but I didn't have any luck googling.
Sorry to hijack but it sounds like you might have an answer I need. I just want a way to put together an iso with a bootloader that works in virtual machines. (I'm good with 32bit grub but I'd work with uefi too).
Viruses don't need to be .exes by the way. There were spectre/meltdown proofs of concept that only ever used front end JavaScript.
Because the modern style of CPU attack (zenbleed too) usually side chains access to private memory (where your authentication details exist) they can get full system control without executing any .exes.
That computer would need a firewall disabling all incoming traffic, the latest bios firmware patches and js disabled on Firefox to be close to safe. And that's the base level stuff.
Edit: changed VPN to firewall. That was silly.