archbootstrap

#!/bin/sh

usage() {
	cat <<EOF
usage:	archbootstrap [options] root

	-a <arch>
	-c <cachedir>
	-h help
	-i show post-install ideas
	-m <mirror>
	-n no-cache
EOF
}

is_root() {
	[ "$(id -u)" = '0' ]
}

use_cache() {
	[ "$no_cache" != 'true' ]
}

show_ideas() {
	[ "$ideas" = 'true' ]
}

cleanup() {
	# delete cache directory if it is a tempdir
	if ! use_cache; then
		if [ -d "$cachedir" ]; then
			rm -r "$cachedir"
		fi
	fi
}
trap cleanup EXIT

while getopts 'a:c:him:n' opt; do
	case "$opt" in
		a) arch=$OPTARG;;
		c) cachedir=$OPTARG;;
		h) usage; exit;;
		i) ideas=true;;
		m) mirror=$OPTARG;;
		n) no_cache=true;;
		*) usage >&2; exit 1;;
	esac
done
shift $((OPTIND - 1))

# accept one argument
if [ $# -ne 1 ]; then
	usage >&2
	exit 1
fi

root=$1
arch=${arch-$(uname -m)}
if use_cache; then
	if is_root; then
		cachedir=${cachedir-/var/cache/archbootstrap}
	else
		cachedir=${cachedir-${XDG_CACHE_HOME-$HOME/.cache}/archbootstrap}
	fi
else
	cachedir=$(mktemp -d)
fi
mirror=${mirror-https://mirrors.kernel.org/archlinux/}
archive=$cachedir/$(
	wget --quiet --output-document - "${mirror}iso/latest/" | \
	grep --only-matching "archlinux-bootstrap-[0-9]\{4\}\.[0-9]\{2\}\.[0-9]\{2\}-$arch.tar.gz" | \
	head -n1)

mkdir -p "$cachedir"

wget --quiet --show-progress --continue --output-document "$archive" "${mirror}iso/latest/$(basename "$archive")"
wget --quiet --show-progress --continue --output-document "$archive.sig" "${mirror}iso/latest/$(basename "$archive").sig"

gpg --verify "$archive.sig" "$archive" || exit $?

mkdir -p "$root"
tar xf "$archive" -C "$root" --strip-components 1

if show_ideas; then
echo
cat <<EOF
post-install ideas:

	sed -i 's/^CheckSpace/#CheckSpace/' /etc/pacman.conf
	echo 'Server = $mirror\$repo/os/\$arch' > /etc/pacman.d/mirrorlist
	echo 'en_US.UTF-8 UTF-8' > /etc/locale.gen
	echo LANG="en_US.UTF-8" > /etc/locale.conf
	ln -s /usr/share/zoneinfo/UTC /etc/localtime

	pacman-key --init
	pacman-key --populate archlinux
	pacman -Syu --needed base --ignore=linux
	locale-gen
EOF
fi