build-image.sh

#!/usr/bin/env bash
set -e

# see http://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/
PART_TYPE="4f68bce3-e8cd-4db1-96e7-fbcaf984b709"

if [ $# -ne 2 ]; then
  echo "Usage: $0 <image-name> <image-size (mb)>"
  exit 1
fi

TARGET="$1"
SIZE="$2"

echo -n "creating..."
dd if=/dev/zero of="$TARGET" bs=1M count="$SIZE" &>/dev/null
echo "done"

echo -n "partitioning..."
sgdisk -o -n 1 -t 1:"$PART_TYPE" -c 1:disk "$TARGET" >/dev/null
echo "done"

echo -n "mounting..."
LOOP=$(kpartx -avs "$TARGET" | grep -oE "loop[0-9]p[0-9]+")
echo "done"

echo -n "formatting..."
mkfs.ext2 "/dev/mapper/$LOOP" >/dev/null
echo "done"

TEMP=$(mktemp -d)

echo -n "mounting root partition..."
mount "/dev/mapper/$LOOP" "$TEMP" > /dev/null
echo "done"

echo -n "installing base system..."
pacstrap -c -d "$TEMP" base >/dev/null
echo "done"

echo -n "cleaning up..."
umount "$TEMP" >/dev/null
kpartx -d "$TARGET" >/dev/null
echo "done"