Make collectd-hack script more robust

modules/rhizo_base/files/collectd-hack

@@ -2,6 +2,10 @@
 
 is_empty () {
   _o=`rrdtool xport DEF:A=/var/lib/collectd/rrd/$(hostname -f)/$1:value:AVERAGE XPORT:A -s -1day -m10 | xmllint --xpath 'string(xport/data/row)' -`
+  if [ $? != 0 ] ; then
+    echo "Error. exiting."
+    exit
+  fi
   if  [ "$_o" == "0.0000000000e+00" ] ;then
     echo "$1 is empty"
     return 1
@@ -12,7 +16,13 @@ is_empty () {
 cd /var/lib/collectd/rrd/$(hostname -f)
 rm -rf gauge-* derive-*
 
+if [ ! -d statsd ] ; then
+  echo "No statsd directory"
+  exit
+fi
+
 for f in statsd/* ; do #gauge-bts.0* statsd/*msc.0* statsd/*vlr.0*; do
+  echo "Checking $f"
   is_empty $f
   if [ $? == 1 ] ; then continue ; fi
   mkdir $(basename $f .rrd)