Script that creates a bootable qcow2 img with a directory's contents - installs mbr and extlinux

dir2img

#!/bin/bash

DIR=${1?usage: $0 <dir> <img>}
OUT=${2?usage: $0 <dir> <img>}

set -e -x

rm -f "$OUT"
trap 'rm -f $OUT' EXIT INT
virt-make-fs --partition=mbr --type=ext3 --format=raw --size=+300M "$DIR" "$OUT"
guestfish -a "$OUT" <<END
launch
mount /dev/sda1 /
part-set-bootable /dev/sda 1 true
extlinux /boot
copy-file-to-device /usr/lib/extlinux/mbr.bin /dev/sda
END
trap '' EXIT INT
if [ -n "$SUDO_USER" ]; then
  chown "$SUDO_USER:$SUDO_USER" "$OUT"
fi