live-build

step	file that runs	purpose
clean (optional)	auto/clean	wipes previous artefacts before each build (debian-live-config.readthedocs.io)
config	auto/config → lb config	writes config/ tree (architectures, kernel, installer, etc.) (debian-live-config.readthedocs.io)
build	auto/build → lb build	launches the full five‑stage pipeline below (debian-live-config.readthedocs.io)

• You will see additional chroot_prep helpers sprinkled around; they transiently mount pseudo‑filesystems or tweak APT inside the build chroot and then undo those changes before packaging the image.

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1. Debugging – run lb build --verbose or insert set ‑x into a helper you want to inspect; each helper is plain POSIX shell.

2. Injecting custom logic – drop executable scripts into config/hooks/<stage>.HOOKEXT (e.g. config/hooks/normal/chroot/99‑myfix.chroot). They will be picked up by the corresponding *_hooks helper.