X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fmatita%2Fscripts%2Fcrontab.sh;h=64708ba77e3916d53917fb9453301a0682177163;hb=1243f49dd307b6e04181b52b64576d872a4eb5c7;hp=99b4a13a6b77abd171c9495eeac3dfdde1af9fbe;hpb=0b8920a44d8e2540dd7e12811b5e485d19664953;p=helm.git

diff --git a/helm/software/matita/scripts/crontab.sh b/helm/software/matita/scripts/crontab.sh
index 99b4a13a6..64708ba77 100644
--- a/helm/software/matita/scripts/crontab.sh
+++ b/helm/software/matita/scripts/crontab.sh
@@ -47,7 +47,23 @@ fi
 CUR_TIME=`echo $SQLQTIME$MARK$SQLQGRMARK | $MYSQL`
 OLD_TIME=`echo $SQLQTIME$LASTMARK$SQLQGRMARK | $MYSQL`
 
-((DELTA=$CUR_CENTS-$OLD_CENTS))
+if [ -z "$CUR_TIME" -o -z "$OLD_TIME"]; then
+    cat <<EOT
+
+    Unable to calculate total time amounts:
+    
+      $SQLQTIME$MARK$SQLQGRMARK 
+      
+    or
+
+      $SQLQTIME$LASTMARK$SQLQGRMARK
+      
+    gave an empty result
+    
+EOT
+fi
+
+((DELTA=$CUR_TIME-$OLD_TIME))
 if [ $DELTA -lt 0 ]; then
   PERC=0
 else