Building a Linux Distro from Scratch

Introduction

Building a Linux distribution from scratch is one of the most rewarding learning experiences for any systems programmer. It forces you to understand how all the pieces fit together—from the bootloader to user space.

Prerequisites

Before we begin, ensure you have:

• A Linux host system (Ubuntu 22.04+ recommended)
• At least 20GB of free disk space
• Basic knowledge of shell scripting
• Patience (this will take time)

Step 1: Setting Up the Build Environment

First, we need to create a clean build environment. We'll use a chroot to isolate our build:

export LFS=/mnt/lfs
mkdir -pv $LFS
mount /dev/sdb1 $LFS

Step 2: Compiling the Kernel

The Linux kernel is the heart of our distribution. We'll compile version 6.1 LTS:

cd /usr/src
wget https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.1.tar.xz
tar xf linux-6.1.tar.xz
cd linux-6.1
make menuconfig
make -j$(nproc)
make modules_install
make install

Step 3: Configuring BusyBox

BusyBox provides essential Unix utilities in a single executable:

wget https://busybox.net/downloads/busybox-1.36.0.tar.bz2
tar xf busybox-1.36.0.tar.bz2
cd busybox-1.36.0
make defconfig
make CONFIG_STATIC=y -j$(nproc)
make install

Step 4: Creating the Root Filesystem

Now we assemble our minimal root filesystem:

mkdir -p $LFS/{bin,sbin,etc,proc,sys,usr/{bin,sbin}}
cp -a busybox-1.36.0/_install/* $LFS/

Step 5: Building a Bootable ISO

Finally, we create a bootable ISO using Syslinux:

mkdir -p iso/boot/syslinux
cp /usr/lib/syslinux/bios/*.c32 iso/boot/syslinux/
cp /usr/lib/syslinux/bios/isolinux.bin iso/boot/syslinux/
xorriso -as mkisofs -o mylinux.iso -b boot/syslinux/isolinux.bin iso/

Conclusion

You now have a minimal but functional Linux distribution. From here, you can add package management, init systems, and desktop environments. The journey of a thousand miles begins with a single step—and you've just taken yours.