#!/usr/bin/perl
use strict;
use warnings;

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

for (grep { !/^\./ } readdir(DIR)) {
    rename $_,sprintf ('%03d-%s',$i++,$_) or warn "Couldn't rename $_: $!";
}