This doesn't work in every OS (it does work in Linux, but I think it doesn't work in solaris)... you can set $0, which will influence what you see when you do a ps:

#!/bin/perl -w

use strict;
my $pr=$0;
for(1..10){
  $0=$pr." processing $_";
  sleep 5;
}
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when I run this code on my linux box and do a ps -ef to see what # it is currently on in the loop....