Linux From Scratch

Automated build of Linux From Scratch 12.4 (SysV) inside a Dockerized Ubuntu 24.04 host.

Layout

Dockerfile             # ubuntu:24.04 build host
Makefile               # end-to-end driver on the host side
packages.txt           # book's wget-list-sysv
md5sums                # book's md5sums
script/
  mkext4.sh            # partition + format + mount the loopback image
  stage0.sh            # create the `lfs` user, $LFS/{sources,tools}, env
  stage1.sh            # as lfs: driver for pkg/prep (ch 5 + 6)
  gen_scripts.py       # regenerate pkg/ from scraped book pages
  extract_book.py      # scrape <pre class="userinput"> from the book
  book-html/           # cached raw snippets (so gen is offline)
pkg/
  prep/                # cross toolchain + cross-compiled temp tools
    *.sh               # one per package, run as the lfs user
    run-prep.sh        # drives them in book order
  build/               # final system, system config, kernel + GRUB
    *.sh               # one per package, run inside chroot
    as-chroot.sh       # inside chroot: runs every build/*.sh in order
    run-build.sh       # outside chroot: mounts vkfs, chroots, -> as-chroot.sh

Build flow

make all chains the following targets:

target	runs
docker-build	build the Ubuntu 24.04 LFS-host image
docker-run	start the container (privileged; sshd on :2222)
mkimg	create/partition/format a sparse loopback image, mount at /mnt/lfs
prep-host	create the lfs user and $LFS/{sources,tools}
dl-sources	wget -i packages.txt into /mnt/lfs/sources
upload-pkgs	bulk-copy pkg/prep and pkg/build into /mnt/lfs/sources
prep-pkgs	(lfs user) run pkg/prep/run-prep.sh — chapters 5+6
build-pkgs	(root) run pkg/build/run-build.sh — chapters 7–10

Individual targets are re-runnable. ssh / ssh-lfs give interactive sessions into the container as root / lfs, which is handy for poking at a failed build.

Resumable builds

run-prep.sh and as-chroot.sh drop a stamp in /mnt/lfs/sources/.done/ after each successful package, and a per-package log in /mnt/lfs/sources/.log/. Re-running make prep-pkgs / make build-pkgs skips anything already stamped, so a failed build resumes where it stopped.

command	effect
make status	list stamped (completed) packages
make logs	list per-package logs by recency
make build-pkgs FORCE=gcc,glibc	re-run those packages even if stamped
make build-pkgs FORCE=all	wipe stamps, rebuild everything
make reset-stamps	same, without kicking off a build

upload-pkgs uses rsync and leaves .done/ and .log/ in place, so edits to a package script followed by make upload-pkgs build-pkgs FORCE=<pkg> is the standard edit-rerun loop.

Regenerating the package scripts

The scripts under pkg/ are generated directly from the book's <pre class="userinput"> blocks. To retarget a future LFS release:

python3 script/extract_book.py script/book-html   # rescrape the book
# Update packages.txt + md5sums from the new book.
# Edit script/slug_map.json if tarball filenames/dirs changed.
python3 script/gen_scripts.py                     # regenerate pkg/prep + pkg/build

Requirements

Host: Docker (privileged containers, so loop devices work) and make. The image pulls https://github.com/mvanveen.keys for SSH auth — change that URL in the Dockerfile if you're not me.

Lint

make lint

runs shellcheck -S warning over every shell script, hadolint on the Dockerfile, bash -n for syntax, and py_compile on the generators.

Distribution layer (pkgsrc on top of LFS)

The LFS base build above gives a self-hosting C/POSIX system. To turn it into a usable distribution, we layer NetBSD's pkgsrc on top, keeping all source artifacts on a dedicated /srv/sources partition.

See docs/pkgsrc-plan.md for the full design, and docs/qemu-boot-test.md for the boot-validation recipe.

Three-prefix layout:

prefix	owner
/usr	LFS (glibc, gcc, coreutils, bash, vim, ...)
/opt/pkg	pkgsrc (bmake / pkgin-managed packages)
/usr/local	BLFS / hand-roll

pkgsrc is quarterly-versioned: prefix /opt/pkg-2025Q3, with /opt/pkg as a symlink so PATH is stable across upgrades. Distfiles cache lives at /srv/sources/distfiles and is shared across quarterlies.

make sources-partition          # seed /srv/sources/lfs from $LFS/sources
make pkgsrc-bootstrap            # clone tree, ./bootstrap into /opt/pkg-2025Q3
make pkgsrc-baseline             # build pkg/pkgsrc-baseline.list