prologin-dd_prololive/update_img.sh

#! /usr/bin/env sh

img="prololive.img"
img_tmp="${img}.tmp"
img_url="http://srv.ordiclic.eu/prololive.img"

if [ ! -f "${img}" ]
then
  local_size=0
  remote_size=1
else
  remote_size=$(curl -s --head "${img_url}" | grep Content-Length | grep -oE [0-9]+)
  local_size=$(stat --printf="%s" "${img}")
fi

if [ "${local_size}" -eq "${remote_size}" ]
then
  echo "Remote image is probably the same"
  exit
fi

rm -f "${img}"

wget "${img_url}" -O "${img_tmp}" || {
  rm "${img_tmp}"
  echo "Failed to download image" >&2
  exit 1
}

mv ${img_tmp} ${img}