I have tried to take a look around the WWW but, as you may have guessed, it only shows me results to create a medium of installation for a determined distribution and not for a custom made system (LFS).

That's why I want to know if you could tell me any information about it or link me to any place where I can read about the subject.

Just to be more clear:

I do not want to create a LIVE installation media, I do not want to have a desktop environment so users can click on an "Install" icon.

I just want a simple terminal system that can be booted up on BIOS and UEFI systems; letting users make partitions and extract the sources (install the system). Something like Debian Net ISO installer or Slackware Installer.

https://github.com/KeithDHedger/LFSBootCD
Based on this:
https://www.phenix.bnl.gov/~purschke/RescueCD/

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Thanks for the links. It will take some to read them fully but, just right now, as far as I could have read, I have some doubts, and those are:

Can I use a static busybox build INSTEAD of using a toolchain to compile a C library thus re-compiling the utilities needed? If so, then that is almost everything I need, right? Just a custom kernel compilation supporting an initial ram disk (initrd), make such initrd. After that, use grub to make a grubx64.efi and efiboot.img for xorriso to use and finally make some more files needed for xorriso to produce the final ISO image? Then burn it to a CD or USB. Is that it?

Would that work good? Or am I missing something?

Havn't got a clue!
Aint used busybox in years.

another option maybe linux live kit https://www.linux-live.org/

1 members found this post helpful.

Thanks, I will take at look at that as well. But first, I will try to do something with busybox since I saw that Slackware uses it for its installer, that could be a good hint.

Now a little update. Yes, it can be done using busybox. If anything else is needed then consider using static, dynamic or hybrid builds, ie: I needed a static fdisk for gpt.

I ended up using a hybrid-method: busybox + static + shared utilities. It works as intended for an installer (temporary ram file system able to boot; enough utilities to install a system).