Add tools for mounting VHD as NBD from Linux

nbd-wait

@@ -0,0 +1,17 @@
+#!/bin/bash
+# wait until nbd is ready
+APP_DIR="$(dirname "$0")"
+NBD_READY="$APP_DIR/nbd-ready"
+INTERVAL=0.5
+
+TIMEOUT=$1
+SECONDS=0
+
+until $NBD_READY; do
+	if [ "$TIMEOUT" ] && (( SECONDS >= "$TIMEOUT" )); then
+		echo "Timeout waiting for NBD" >&2
+		exit 1
+	fi
+	
+	sleep $INTERVAL
+done