diff --git a/tutorial/lisa2011/rrd-by-example/ex/v-interfaces.pl b/tutorial/lisa2011/rrd-by-example/ex/v-interfaces.pl
--- /dev/null
@@ -0,0 +1,16 @@
+#!/usr/bin/perl -w
+use strict;
+use lib qw( /scratch/rrd4/lib/perl );
+use RRDs;
+my $out = RRDs::graphv(
+ '-', '--start' => '00:00 20080916',
+ '--end' => 'start+8d',
+ '--lower-limit' => 0,
+ '--imgformat' => 'PDF',
+ 'DEF:a=hw-demo.rrd:in:AVERAGE',
+ 'LINE1:a#c00:InOctets');
+my $ERROR = RRDs::error;
+die "ERROR: $ERROR\n" if $ERROR;
+map {
+ print $_.' = '.substr($out->{$_},0,8)."\n"
+} sort keys %$out;