Arch Offline Installer / DualBoot ISO

This project builds a custom Arch Linux ISO that can install Arch fully offline, with or without a DualBoot setup alongside Windows.

build_iso.sh

Builds the ISO. It:

1. Installs archiso if missing, then copies the releng profile as a base.
2. Downloads all packages and their dependencies into an offline repo (/var/cache/offline-repo).
3. Embeds install_arch.sh into the ISO so it runs automatically at boot on tty1.
4. Creates two pacman.conf variants:
   • online — for the ISO live environment.
   • offline — points at the bundled repo (file:///var/cache/offline-repo/), used by the installer.
5. Writes ISO metadata (arch-offline-installer, label ARCH_OFFLINE).
6. Runs mkarchiso and copies the resulting .iso to the project directory.

install_arch.sh

Automated installer that runs when booting the ISO. Steps:

1. Mode selection — DualBoot (alongside an existing OS) or Full Wipe (erases the disk).
2. Disk selection — Lists available disks, excludes the boot medium.
3. Windows detection — Finds the Windows EFI partition for chainloading.
4. Free space detection (DualBoot) — Finds the largest free region (min 10 GiB).
5. User input — Hostname, username, password.
6. Encryption — Optional LUKS2 root encryption.
7. Partitioning — EFI (2 GiB, FAT32) + Btrfs root in free space or full disk.
8. Filesystems — Btrfs with subvolumes (@, @home, @snapshots, @log), mounts EFI at /boot, copies Windows bootloader for chainloading.
9. Installation — pacstrap from the offline repo when available, else online.
10. Chroot configuration — Timezone, locale, hostname, user creation, sudo, mkinitcpio (btrfs + encrypt hooks), Limine bootloader, zram-generator, NetworkManager.
11. Cleanup — Offers to reboot.

Bootloader

Uses Limine (UEFI). DualBoot adds a chainload entry for Windows.

Offline repo

The ISO carries a full package cache so the installation can run without internet.

Installation Flow