Check headers

  TMP="/tmp/agent.sh"

  rm -f "${TMP}"

  URL="https://raw.githubusercontent.com/kroese/virtual-dsm/master/agent/agent.sh"

  # Auto update the agent

  remote_size=$(curl -s -I -k -m 3 "${URL}" | awk '/Content-Length/ {sub("\r",""); print $2}')

  echo "remote size: $remote_size"

  [ "$remote_size" == "0" ] && return

  if ! curl -s -f -k -m 10 -o "${TMP}" "${URL}"; then

    echo "$HEADER: curl error" && return

  fi

  if ! curl -s -f -k -m 3 -o "${TMP}" https://raw.githubusercontent.com/kroese/virtual-dsm/master/agent/agent.sh; then

    #echo "$HEADER: curl error" && return

    return

delay=5000

difference=0

elapsed=$((($(date +%s%N) - $ts)/1000000))

echo "elapsed: $elapsed"

if (( delay > elapsed )); then

  difference=$((delay-elapsed))

  echo "firstdiff: $difference"

  float=$(echo | awk -v diff=\""$difference\"" '{print diff * 0.001}')

  echo "Elapsed time: $elapsed, difference: $float"

  float=$(echo | awk -v diff=\""$difference"\" '{print diff * 0.001}')

  echo "Elapsed time: $elapsed, sleep: $float"

  sleep $difference

fi