Script to install Arch Linux on a virtual machine.

arch-linux-vm-install

#!/bin/bash
#
# This is an Arch Linux installation script for UEFI virtual machines.

# Btrfs note: CoW can negatively affect performance with large files that have
# small random writes. Disable CoW for databases and virtual machine images.
#
# To disable CoW for single files/directories do:
# $ chattr +C /dir/file

# Drives
# sda is 256 GB HDD

# Filesystem tree.
# [s] = subvolume
# [d] = directory
#
# /dev/sda1 [esp] (HDD) 1024M for EFI System Partition
#
# /dev/sda2 [arch] (HDD)
# |
# +-- [s] rootvol      /
# +-- [s] boot         /boot
# +-- [s] opt          /opt
# +-- [s] srv          /srv
# +-- [s] home         /home
# +-- [s] data         /data
# +-- [s] var          /var
# +-- [s] pacmanpkg    /var/cache/pacman/pkg
# +-- [s] abs          /var/abs
# +-- [s] var-cache    /var/cache
# +-- [s] var-log      /var/log
# +-- [s] var-spool    /var/spool
# +-- [s] var-tmp      /var/tmp
# +-- [d] snapshots
#     |
#     +-- [s] rootvol    /.snapshots
#     +-- [s] home       /home/.snapshots
#     +-- [s] var        /var/.snapshots

confirm_to_run_command() {
  local response
  read -r -p "Run command: \`$1\` ? [Y/N] " response

  if [[ ! "${response}" =~ ^([yY][eE][sS]|[yY])$ ]]; then
    exit 0
  fi

  echo -e '\n'
  
  eval "$1"
}

clear

echo -e 'Installing Arch Linux on virtual machine...\n'

# Verify the boot mode.
# To check to boot mode we can also test if the following path exists, like so:
#
# ls /sys/firmware/efi/efivars
#
# If it exists the system is booted in UEFI mode otherwise it may be booted in
# BIOS or CSM mode.
confirm_to_run_command 'efivar -l'

if [ -f /sys/firmware/efi/efivars ]; then
  echo -e 'System is booted in UEFI mode.\n'
else
  echo -e 'System is booted in BIOS mode.\n'
fi

# Connect to the internet.
# Since the VM is on a wired connection so it might just work right away.
# Configuration is needed for wireless connections.
confirm_to_run_command 'ping -c 3 archlinux.org'

# Update the system clock.
confirm_to_run_command 'timedatectl set-ntp true'
confirm_to_run_command 'timedatectl set-timezone Asia/Karachi'
confirm_to_run_command 'timedatectl status'

# View disks and partitions.
confirm_to_run_command 'lsblk'

# Erase the partition table. Zero out the first 10000 blocks of the disk.
confirm_to_run_command 'sgdisk --zap-all /dev/sda'
confirm_to_run_command 'dd if=/dev/zero of=/dev/sda bs=1M count=10000 status=progress'

# View disks and partitions again to ensure udev has given them the names
# (i.e. /dev/sdX where X is a, b, c, etc.) you'd want them to have.
confirm_to_run_command 'lsblk'

# Check UEFI mode (if UEFI variable prints you're in UEFI mode).
confirm_to_run_command 'efivar -l'

# Use cgdisk to create GPT partitions.
# UEFI and BIOS are going to have different partition layouts.
#
# 1024 MB FAT32 "esp" partition; cgdisk code ef00.
# The rest for btrfs "arch" partition; cgdisk code 8300.
confirm_to_run_command 'cgdisk /dev/sda'

# Check if the disk partitions are set as desired.
confirm_to_run_command 'lsblk'

# Format partitions with desired filesystems.
confirm_to_run_command 'mkfs.fat -F32 -n esp /dev/sda1'
confirm_to_run_command 'mkfs.btrfs -L arch /dev/sda2'

# Mount main btrfs partition.
confirm_to_run_command 'mkdir -p /mnt/btrfs-root'
confirm_to_run_command 'mount /dev/sda2 /mnt/btrfs-root'

# Create btrfs subvolumes for system.
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/rootvol'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/boot'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/opt'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/srv'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/home'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/data'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/var'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/pacmanpkg'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/abs'
# abs is Arch Build System. It's created inside var/abs but subvol is called
# abs; not var-abs.
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/var-cache'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/var-log'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/var-spool'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/var-tmp'

# Create btrfs subvolumes for snapshots.
confirm_to_run_command 'mkdir -p /mnt/btrfs-root/snapshots'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/snapshots/rootvol'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/snapshots/home'
confirm_to_run_command 'btrfs subvolume create /mnt/btrfs-root/snapshots/var'

# List all subvolumes for /mnt/btrfs-root.
confirm_to_run_command 'btrfs subvolume list -a /mnt/btrfs-root'

# Unmount.
confirm_to_run_command 'umount -R /mnt/btrfs-root'

# Mount root subvolume.
confirm_to_run_command 'mount -o subvol=rootvol /dev/sda2 /mnt/btrfs-root'

# Create directories in the root subvolume and mount other subvolumes.
# Don't change the order of the commands since to create directories inside
# another subvolume it should be mounted first.
confirm_to_run_command 'mkdir -p /mnt/btrfs-root/{boot,home,data,var,opt,srv,.snapshots}'

confirm_to_run_command 'mount -o subvol=boot /dev/sda2 /mnt/btrfs-root/boot'
confirm_to_run_command 'mount -o subvol=home /dev/sda2 /mnt/btrfs-root/home'
confirm_to_run_command 'mount -o subvol=data /dev/sda2 /mnt/btrfs-root/data'
confirm_to_run_command 'mount -o subvol=var /dev/sda2 /mnt/btrfs-root/var'
confirm_to_run_command 'mount -o subvol=opt /dev/sda2 /mnt/btrfs-root/opt'
confirm_to_run_command 'mount -o subvol=srv /dev/sda2 /mnt/btrfs-root/srv'
confirm_to_run_command 'mount -o subvol=snapshots/rootvol /dev/sda2 /mnt/btrfs-root/.snapshots'

confirm_to_run_command 'mkdir -p /mnt/btrfs-root/var/{abs,cache,log,spool,tmp,.snapshots}'
confirm_to_run_command 'mkdir -p /mnt/btrfs-root/home/.snapshots'
confirm_to_run_command 'mount -o subvol=abs /dev/sda2 /mnt/btrfs-root/var/abs'
confirm_to_run_command 'mount -o subvol=var-cache /dev/sda2 /mnt/btrfs-root/var/cache'
confirm_to_run_command 'mount -o subvol=var-log /dev/sda2 /mnt/btrfs-root/var/log'
confirm_to_run_command 'mount -o subvol=var-spool /dev/sda2 /mnt/btrfs-root/var/spool'
confirm_to_run_command 'mount -o subvol=var-tmp /dev/sda2 /mnt/btrfs-root/var/tmp'
confirm_to_run_command 'mount -o subvol=snapshots/home /dev/sda2 /mnt/btrfs-root/home/.snapshots'
confirm_to_run_command 'mount -o subvol=snapshots/var /dev/sda2 /mnt/btrfs-root/var/.snapshots'

confirm_to_run_command 'mkdir -p /mnt/btrfs-root/var/cache/pacman/pkg'
confirm_to_run_command 'mount -o subvol=pacmanpkg /dev/sda2 /mnt/btrfs-root/var/cache/pacman/pkg'

# List all subvolumes for /mnt/btrfs-root.
confirm_to_run_command 'btrfs subvolume list -a /mnt/btrfs-root'

# Mount EFI System Partition.
confirm_to_run_command 'mkdir -p /mnt/btrfs-root/boot/efi'
confirm_to_run_command 'mount /dev/sda1 /mnt/btrfs-root/boot/efi'

# Select a mirror.
confirm_to_run_command 'nano /etc/pacman.d/mirrorlist'

# Check internet connection.
# It should already be connected since this VM has a wired connection.
confirm_to_run_command 'ping -c 3 www.google.com'

echo -e 'End of script.\n'