#!/usr/bin/perl

$dir = "/home/my/files" ;
chdir $dir or die "$!";
opendir(DIR,$dir ) or die "$!";
$i = 1;

@files = grep { !/^\./ } readdir(DIR);
foreach (@files) {
    $new = $_;
    $new =~ s/$new/sprintf ("%03d-%s",$i,$_)/e;
    rename $_,$new;
    $i++;
}