--- a/apt-feed-logbuch.sh	Wed Jun 08 15:56:23 2011 +0200
+++ b/apt-feed-logbuch.sh	Wed Jun 08 15:58:43 2011 +0200
@@ -19,6 +19,16 @@
     . /etc/default/ius.upgrade.conf
 fi
 
+if ! test -f "$LINES_COUNT"; then
+    echo "$0: $LINES_COUNT is missing" >&2
+    exit 0
+fi
+
+if ! test -s "$LINES_COUNT"; then
+    echo "$0: $LINES_COUNT is empty" >&2
+    exit 0
+fi
+
 APT_CMD=$(ps -p $1 -o args=)
 APT_TMP="/tmp/$$.tmp"
 APT_OUT="/tmp/$$.out"