--- a/pdd	Sun Nov 04 20:36:22 2012 +0100
+++ b/pdd	Sun Nov 04 20:38:55 2012 +0100
@@ -4,16 +4,22 @@
 use strict;
 use warnings;
 use threads;
+use Getopt::Long;
 
 sub dd;
 sub timer;
 sub main;
 sub kbd;
 
+our $o_interval = 10;
+
 MAIN: {
     $| = 1;
     my $dd;
 
+    GetOptions("i|interval=i" => \$o_interval)
+	or die "Usage: $0 [-i|--interval n] <dd options>\n";
+
     $SIG{INT} = sub {
         if (defined $dd) {
             warn "Got $_[0], going to kill dd(pid:$dd)\n";
@@ -96,7 +102,7 @@
     while (1) {
         sleep 1;
         kill "USR1" => $pid
-          if ++$i % 10 == 0;
+          if ++$i % $o_interval == 0;
     }
 }