Introduction

Linux From Scratch (LFS) is the ultimate DIY project for Linux enthusiasts who want to understand every piece of their operating system. Rather than relying on pre-built distributions, LFS walks you through compiling and installing each component from source. If you’ve ever wondered what goes on under the hood of your favorite distro, this is the way to find out. Plus, it gives you bragging rights. Imagine telling your friends, “Oh, that shiny new kernel? I built it myself!”

This tutorial will guide you through the painstaking yet rewarding process of creating your very own Linux system from scratch. Buckle up, caffeinate, and prepare for serious geekery… with a dash of humor to keep your sanity intact.

Prerequisites

Before embarking on this epic quest, make sure you have:

• A host system running a modern Linux distro (for compiling tools).
• At least 20 GB of free disk space (you’ll need room for sources, build directories, and tmpfs mounts).
• A user with sudo/root privileges (because you will be juggling partitions and installing critical system files).
• Patience (LFS is not a weekend project—expect days of compiling).
• The latest LFS book from the official site: LFS Download.

Overview of Steps

1. Prepare the host system and partition your disk.
2. Download LFS sources and patches.
3. Create a dedicated LFS user and environment.
4. Build a temporary toolchain.
5. Enter the LFS build environment (chroot).
6. Compile and install all packages in chapter order.
7. Configure the system (fstab, networking, user accounts).
8. Install a bootloader (GRUB).
9. Reboot into your new LFS system.

1. Preparing the Host System

Create Partitions

Use your preferred partitioning tool (fdisk, cfdisk, parted). Here’s a basic scheme:

Example commands:

• mkfs.ext4 /dev/sda1
• mkfs.ext4 /dev/sda2
• mkswap /dev/sda3 swapon /dev/sda3
• mount /dev/sda2 /mnt/lfs then mkdir /mnt/lfs/boot mount /dev/sda1 /mnt/lfs/boot

Set Up Environment Variables

Define where your LFS system resides and the number of parallel build jobs:

export LFS=/mnt/lfs
export LFS_TGT=(uname -m)-lfs-linux-gnu
export MAKEFLAGS=-j 4
  

2. Download Sources and Patches

From LFS Download, grab:

• The packages tarballs (binutils, gcc, glibc, etc.).
• The patches for the packages.
• The md5sums file for integrity checking.

Organize them:

mkdir -v LFS/sources
chmod -v a wt LFS/sources
cp /path/to/downloads/ LFS/sources
  

Verify your downloads:

cd LFS/sources
md5sum -c md5sums
  

3. Create LFS User and Tools Directory

For safety, do all building as a non-root user:

groupadd lfs
useradd -s /bin/bash -g lfs -m -k /dev/null lfs
passwd lfs
chown -v lfs LFS/tools
  

Switch to the LFS user:

su - lfs
  

4. Building the Temporary Toolchain

This is the foundation. You’ll compile Binutils, GCC, Glibc, and friends in a special environment so they don’t rely on your host’s libraries. Key highlights:

• Build Binutils 2.###
• Build GCC 10.### (two-stage: bootstrap and final)
• Build Glibc 2.###

Each package follows the pattern:

1. Extract: tar -xf package.tar.xz
2. Enter build dir: mkdir build cd build
3. Configure: ../configure --prefix=LFS/tools --with-sysroot=LFS --target=LFS_TGT [other flags]
4. Compile: make
5. Install: make install

If a configure step bombs, read the error, google the missing header/flag, and adjust flags or install a host package. Don’t just press ‘go again’ without understanding why.

5. Entering the Chroot Environment

At this point, you have a self-hosting toolchain in LFS/tools. Now you prepare a clean environment:

mkdir -pv LFS/{dev,proc,sys,run}
sudo mount -v --bind /dev LFS/dev
sudo mount -vt devpts devpts LFS/dev/pts
sudo mount -vt proc proc LFS/proc
sudo mount -vt sysfs sysfs LFS/sys
sudo mount -vt tmpfs tmpfs LFS/run
chroot LFS /usr/bin/env -i 
  HOME=/root 
  TERM=TERM 
  PATH=/bin:/usr/bin:/sbin:/usr/sbin:/tools/bin 
  /tools/bin/bash --login  h
  

Welcome to the heart of your future OS. Everything from here on builds inside this environment.

6. Building the Base System

Follow the chapters in the LFS book. You’ll compile dozens of packages:

General steps for each:

• Extract the tarball in /sources.
• Configure with --prefix=/usr or according to the book.
• Compile (hint: make -j(nproc)).
• Install (make install, install -v -m0755, etc.).
• Strip symbols to save space (strip --strip-debug).

Between each chapter, read carefully. Dependencies are your mortal enemy: missing libX will break appY.

7. System Configuration

/etc/fstab

# Device      Mount Point  FS-Type  Options       Dump  Pass#
/dev/sda2     /            ext4     defaults      1     1
/dev/sda1     /boot        ext4     defaults      1     2
/dev/sda3     none         swap     sw            0     0
  

Network Setup

• Edit /etc/hosts and /etc/hostname.
• Create /etc/sysconfig/network-scripts/ifcfg-eth0 for static or DHCP.

Users and Passwords

passwd          # set root password
useradd -m -G wheel yourusername
passwd yourusername
  

8. Installing the Bootloader (GRUB)

Install GRUB to the MBR or UEFI partition:

grub-install /dev/sda
cat > /boot/grub/grub.cfg ltlt EOF
set default=0
set timeout=5

menuentry My LFS Linux {
    linux   /boot/vmlinuz-5.10.##-lfs root=/dev/sda2 ro
    initrd  /boot/initramfs-5.10.##.img
}
EOF
  

Adjust kernel name and root device accordingly. For UEFI, mount an EFI partition and use --target=x86_64-efi.

9. Reboot and Enjoy

Exit the chroot, unmount everything, and reboot:

exit
sudo umount -v LFS/{dev/pts,dev,proc,sys,run}
reboot
  

If all goes well, you’ll be greeted by your very own LFS system. Cue triumphant music!

Troubleshooting Tips

• Build fails: Reread the error message, search mailing lists, and check the LFS FAQ.
• Chroot won’t enter: Verify mounts /dev, /proc, /sys must be bound.
• Network down: Double-check interface names with ip link—they can be weird (eth0 is so 2010!).
• Kernel panic: Confirm root= in grub.cfg matches your root partition.

Remember: Google is your friend, and so are the LFS FAQ and the community forums.

Final Thoughts

Building Linux From Scratch is like assembling a 1,000-piece jigsaw puzzle—only the pieces are code, and the sky is the limit. You’ll learn how libraries tie together, how compilers link, and you’ll gain deep respect for your distro maintainers. Plus, you can finally say you own your system.

Enjoy the ride, and may your compile times be short and your coffee strong!