Index: trunk/ippScripts/scripts/diff_skycell.pl
===================================================================
--- trunk/ippScripts/scripts/diff_skycell.pl	(revision 31435)
+++ trunk/ippScripts/scripts/diff_skycell.pl	(revision 31941)
@@ -40,4 +40,6 @@
 my ($skycell_id, $diff_skyfile_id);
 my ($use_convolved);
+my $zaplog = 0;
+
 GetOptions(
     'diff_id=s'         => \$diff_id, # Diff identifier
@@ -55,4 +57,5 @@
     'no-op'             => \$no_op, # Don't do any operations?
     'redirect-output'   => \$redirect,
+    'zaplog'            => \$zaplog, # delete any previous log file
 ) or pod2usage( 2 );
 
@@ -82,4 +85,6 @@
     $logDest .= '.update';
     # ... well we can just do the dirty work here
+    $ipprc->kill_file($logDest);
+} elsif ($zaplog) {
     $ipprc->kill_file($logDest);
 }