Building a Minimal Linux System

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This guide will take you step-by-step through the process of building a minimal Linux system using Arch Linux's pacman package manager as the foundation. Please ensure you have sudo privileges, as they are required for most of the tasks.

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1. Set Up Your Working Directory

Start by setting an environment variable to specify where your new filesystem will be built:

export WORKDIR=$HOME/workdir

Now, create the working directory and subdirectories for your new operating system:

mkdir -p $WORKDIR && cd $WORKDIR
mkdir -p etc/pacman.d var/lib/pacman

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2. Configure Network Resolution

For pacman to function, you need to set up domain name resolution. Create a resolv.conf file with your preferred DNS servers. The default configuration uses Cloudflare's DNS, but you can easily switch to Google, OpenDNS, or others by uncommenting the respective lines:

cat > etc/resolv.conf << "EOF"
# Cloudflare (Default)
nameserver 1.1.1.1
nameserver 1.0.0.1
nameserver 2606:4700:4700::1111
nameserver 2606:4700:4700::1001

# Google
#nameserver 8.8.8.8
#nameserver 8.8.4.4
#nameserver 2001:4860:4860::8888
#nameserver 2001:4860:4860::8844

# OpenDNS
#nameserver 208.67.222.222
#nameserver 208.67.220.220
#nameserver 2620:119:35::35
#nameserver 2620:119:53::53

# Others (uncomment as needed)
#nameserver 9.9.9.9
#nameserver 94.140.14.14
EOF

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3. Set Up Pacman Configuration

Create a pacman.conf file to inform pacman where to download packages. Initially, signature checks are disabled to avoid potential GPG errors. These can be enabled later once the system is set up:

cat > etc/pacman.conf << "EOF"
[options]
Architecture = auto

[core]
SigLevel = Never 
Include = /etc/pacman.d/mirrorlist

[extra]
SigLevel = Never
Include = /etc/pacman.d/mirrorlist

[community]
SigLevel = Never
Include = /etc/pacman.d/mirrorlist
EOF

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4. Select Package Mirrors

Download a list of package mirrors tailored to your region. The following example uses South African mirrors. You can adjust this to your location by fetching the relevant mirrorlist from Arch Linux's mirrorlist:

cat > etc/pacman.d/mirrorlist << "EOF"
## South Africa
Server = http://archlinux.za.mirror.allworldit.com/archlinux/$repo/os/$arch
Server = https://archlinux.za.mirror.allworldit.com/archlinux/$repo/os/$arch
Server = http://za.mirror.archlinux-br.org/$repo/os/$arch
Server = http://za.mirrors.cicku.me/archlinux/$repo/os/$arch
Server = https://za.mirrors.cicku.me/archlinux/$repo/os/$arch
Server = http://mirror.is.co.za/mirror/archlinux.org/$repo/os/$arch
Server = http://mirrors.urbanwave.co.za/archlinux/$repo/os/$arch
Server = https://mirrors.urbanwave.co.za/archlinux/$repo/os/$arch
EOF

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5. Install Essential Tools

To avoid the complexity of building everything from scratch, download static versions of pacman and bash that can operate in your minimal environment:

sudo wget https://pkgbuild.com/~morganamilo/pacman-static/x86_64/pacman-static-6.0.1-2-x86_64.pkg.tar.xz
sudo tar xJf pacman-static-6.0.1-2-x86_64.pkg.tar.xz
sudo rm pacman-static-6.0.1-2-x86_64.pkg.tar.xz
sudo mv usr/bin/pacman-static usr/bin/pacman
sudo mv usr/bin/pacman-conf-static usr/bin/pacman-conf
sudo mv usr/bin/testpkg-static usr/bin/testpkg
sudo mv usr/bin/vercmp-static usr/bin/vercmp

sudo wget https://github.com/robxu9/bash-static/releases/download/5.2.015-1.2.3-2/bash-linux-x86_64
sudo mv bash-linux-x86_64 usr/bin/bash
sudo chmod +x usr/bin/bash
ln -s usr/bin bin

Note: This guide focuses on the x86_64 architecture.

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6. Mount Essential Filesystems

Mount the necessary virtual filesystems to your working directory:

mkdir -p $WORKDIR/{dev,proc,sys,run}
sudo mount --bind /dev $WORKDIR/dev
sudo mount -t devpts devpts -o gid=5,mode=0620 $WORKDIR/dev/pts
sudo mount -t proc proc $WORKDIR/proc
sudo mount -t sysfs sysfs $WORKDIR/sys
sudo mount -t tmpfs tmpfs $WORKDIR/run

if [ -h $WORKDIR/dev/shm ]; then
    sudo install -v -d -m 1777 $WORKDIR$(realpath /dev/shm)
else
    sudo mount -vt tmpfs -o nosuid,nodev tmpfs $WORKDIR/dev/shm
fi

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7. Enter the Chroot Environment

Now that everything is set up, enter the chroot environment:

sudo chroot $WORKDIR

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8. Initial Package Installation

To install the initial packages, follow these steps:

1. Update the Package List:

   In the chroot environment, refresh the pacman package list:

   pacman -Sy

2. Clean Up Existing Binaries:

   Open a second terminal, navigate to your $WORKDIR, and delete the existing bin/bash and bin directories to prevent conflicts:

   cd ${WORKDIR:?}
   sudo rm -rf bin/bash bin

3. Install Essential Packages:

   Return to the chroot environment and install essential packages, starting with bash:

   pacman -S bash

Now, you're ready to install additional packages and continue building your minimal Linux system.

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License

This project is licensed under the MIT License - see the LICENSE file for details.

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Contributing

Contributions are welcome! Feel free to open an issue or submit a pull request.