Arch Linux

thames_r

Member

Registered: 2024-06-14

Posts: 1

Writing Arch Linux Custom Install Script

Hi there. Since i'm always breaking things when tinkering with my system i wanted to make the reinstallation process less cumbersome. Archinstall usually works but has some weird bugs like disabling btrfs compression and HSM straight up not working. So i wanted to try and write a custom installation script in bash that would cater to my needs. I was wondering if any bash veterans could take a look at my code and tell me if i'm missing something, any help is appreciated.

What i'm trying to achieve with this script:

    btrfs filesystem with compression and the standard subvolume layout

    grub as the bootloader

    Disk encryption with LUKS that decrypts automatically via TPM so that i don't have to type my password twice (i'm lazy)

    Both Linux and Linux-LTS kernels

    Zram swap

    Some other programs that are specific for my setup (Nvidia drivers, Intel ucode, tlp for my laptop, hyprland as my wm, etc.)

Anyway, here's the script. If anyone is willing to take a look and tell me what's missing i'd appreciate it very much:

 #!/bin/bash

set -e
trap 'echo "An error occurred. Exiting..."; exit 1;' ERR
trap 'echo "Script interrupted. Exiting..."; exit 1;' SIGINT

# Check for root privileges
if [ "$EUID" -ne 0 ]; then
  echo "Please run as root."
  exit 1
fi

# Prompt for user inputs
read -p "Enter the disk to install Arch Linux on (e.g., /dev/sda): " DISK
if [ ! -b "${DISK}" ]; then
  echo "The specified disk ${DISK} does not exist."
  exit 1
fi

read -p "Enter the hostname for this installation: " HOSTNAME
read -p "Enter the locale (e.g., en_US.UTF-8): " LOCALE
read -p "Enter the timezone (e.g., America/Argentina/Buenos_Aires): " TIMEZONE
read -p "Enter username for the new user: " USER_NAME

# Prompt for passwords
read -s -p "Enter password for ${USER_NAME}: " USER_PASSWORD
echo
read -s -p "Confirm password: " USER_PASSWORD_CONFIRM
echo
if [ "$USER_PASSWORD" != "$USER_PASSWORD_CONFIRM" ]; then
  echo "Passwords do not match."
  exit 1
fi

# Ensure the disk is correct
echo "WARNING: The selected disk is ${DISK}. This will delete all data on this disk."
read -p "Are you sure you want to continue? (yes/no): " CONFIRM
if [ "$CONFIRM" != "yes" ]; then
  echo "Operation cancelled."
  exit 1
fi

# Update system clock
timedatectl set-ntp true

# Configure the fastest mirrors
pacman -Sy --noconfirm reflector
reflector --age 12 --protocol https --sort rate --save /etc/pacman.d/mirrorlist
pacman -Syy

# Partition the disk
EFI_PARTITION="${DISK}1"
ROOT_PARTITION="${DISK}2"

wipefs -a ${DISK}
sgdisk -o ${DISK}
sgdisk -n 1:0:+512M -t 1:ef00 ${DISK}   # EFI partition
sgdisk -n 2:0:0 -t 2:8300 ${DISK}       # Linux filesystem

# Setup encryption with LUKS and TPM
echo -n "${USER_PASSWORD}" | cryptsetup -y --use-random luksFormat ${ROOT_PARTITION}
echo -n "${USER_PASSWORD}" | cryptsetup open --type luks ${ROOT_PARTITION} cryptroot

# Format the filesystems
mkfs.vfat -F32 ${EFI_PARTITION}
mkfs.btrfs /dev/mapper/cryptroot

# Create Btrfs subvolumes
mount /dev/mapper/cryptroot /mnt
btrfs subvolume create /mnt/@
btrfs subvolume create /mnt/@home
btrfs subvolume create /mnt/@var
btrfs subvolume create /mnt/@snapshots
umount /mnt

# Mount the filesystems
mount -o noatime,compress=zstd,subvol=@ /dev/mapper/cryptroot /mnt
mkdir -p /mnt/{boot,home,var,.snapshots}
mount -o noatime,compress=zstd,subvol=@home /dev/mapper/cryptroot /mnt/home
mount -o noatime,compress=zstd,subvol=@var /dev/mapper/cryptroot /mnt/var
mount -o noatime,compress=zstd,subvol=@snapshots /dev/mapper/cryptroot /mnt/.snapshots
mount ${EFI_PARTITION} /mnt/boot

# Install essential packages
ESSENTIAL_PACKAGES="base linux linux-lts linux-firmware util-linux sudo btrfs-progs intel-ucode tpm2-tools clevis lvm2 grub grub-efi-x86_64 efibootmgr zramswap"
ADDITIONAL_PACKAGES="networkmanager network-manager-applet dialog wpa_supplicant mtools dosfstools reflector base-devel linux-headers avahi xdg-user-dirs xdg-utils gvfs gvfs-smb nfs-utils inetutils dnsutils bluez bluez-utils alsa-utils pipewire pipewire-alsa pipewire-pulse pipewire-jack bash-completion openssh timeshift rsync acpi acpi_call tlp dnsmasq ipset ufw flatpak sof-firmware nss-mdns acpid os-prober ntfs-3g wget git gcc neovim btop hyprland xdg-desktop-portal xdg-desktop-portal-hyprland kitty polkit-kde-agent qt5-wayland qt6-wayland rofi-wayland firefox vlc obs-studio grim slurp obsidian"

pacstrap /mnt $ESSENTIAL_PACKAGES

# Generate fstab
genfstab -U /mnt >> /mnt/etc/fstab

# Change root into the new system
arch-chroot /mnt /bin/bash <<EOF

# Set the timezone
ln -sf /usr/share/zoneinfo/${TIMEZONE} /etc/localtime
hwclock --systohc

# Set the locale
echo "${LOCALE} UTF-8" >> /etc/locale.gen
locale-gen
echo "LANG=${LOCALE}" > /etc/locale.conf

# Set the hostname
echo "${HOSTNAME}" > /etc/hostname

# Configure hosts file
cat <<EOT > /etc/hosts
127.0.0.1   localhost
::1         localhost
127.0.1.1   ${HOSTNAME}.localdomain ${HOSTNAME}
EOT

# Initramfs
cat <<EOT > /etc/mkinitcpio.conf
MODULES=(btrfs tpm2)
BINARIES=()
FILES=()
HOOKS=(base udev autodetect modconf block encrypt filesystems)
EOT

mkinitcpio -P

# Create a new user and set the password
useradd -m -G wheel -s /bin/bash ${USER_NAME}
echo "${USER_NAME}:${USER_PASSWORD}" | chpasswd

# Give the new user sudo privileges
echo "%wheel ALL=(ALL) ALL" >> /etc/sudoers

# Install additional packages
pacman -S --noconfirm $ADDITIONAL_PACKAGES

# Enable services
systemctl enable NetworkManager
systemctl enable bluetooth
systemctl enable sshd
systemctl enable avahi-daemon
systemctl enable tlp
systemctl enable reflector.timer
systemctl enable fstrim.timer
systemctl enable ufw
systemctl enable acpid

# Configure ZRAM
cat <<EOT > /etc/systemd/zram-generator.conf
[zram0]
zram-size = ram / 2
compression-algorithm = zstd
EOT

# Install GRUB
grub-install --target=x86_64-efi --efi-directory=/boot --bootloader-id=GRUB
grub-mkconfig -o /boot/grub/grub.cfg

# TPM2 automatic unlock
echo "Adding TPM2 unlock key to LUKS..."
echo -n "${USER_PASSWORD}" | clevis luks bind -d /dev/disk/by-uuid/$(blkid -s UUID -o value ${ROOT_PARTITION}) tpm2 '{"pcr_ids":"7"}'

# Lock the root account
passwd -l root

EOF

# Unmount filesystems
umount -R /mnt

# Close cryptroot
cryptsetup close cryptroot

# Sync and reboot
echo "Installation complete. The system will reboot in 5 seconds."
sleep 5
sync
reboot 

Last edited by thames_r (2024-06-14 19:05:33)

Awebb

Member

Registered: 2010-05-06

Posts: 6,622

Re: Writing Arch Linux Custom Install Script

Do those systemctl calls in arch-chroot actually work?

cryptearth

Member

Registered: 2024-02-03

Posts: 1,048

Re: Writing Arch Linux Custom Install Script

Do those systemctl calls in arch-chroot actually work?

for enable/disable - yes

@OP
You already use BtrFS - why not use its snapshots? Would be easier than reinstall the entire system all the time
or maybe use a vm instead?

macromal

Member

Registered: 2024-08-03

Posts: 12

Re: Writing Arch Linux Custom Install Script

You must set the following kernel parameters to unlock the encrypted root partition at boot:

# Configuring the boot loader
if [ "$encrypt" -eq 1 ]; then
        params="cryptdevice=UUID=$(blkid -s UUID -o value "$luks_part"):cryptlvm root=/dev/vg1/root"
        sed -i "/GRUB_CMDLINE_LINUX=/ s|\"\"|\"$params\"|" /etc/default/grub
fi

# Boot loader
if [ "$removable" -eq 1 ]; then
        grub-install --target=i386-pc "$disk" --recheck
        grub-install --target=x86_64-efi --efi-directory=/efi --removable --recheck

elif [ -f /sys/firmware/efi/fw_platform_size ]; then
        grub-install --target=x86_64-efi --efi-directory=/efi --bootloader-id=GRUB
else
        grub-install --target=i386-pc "$disk"
fi

# Generate the main configuration file
grub-mkconfig -o /boot/grub/grub.cfg

Last edited by macromal (2024-08-03 14:01:26)