#!/usr/bin/env perl
use warnings;
use strict;
use File::Copy qw/move/;
use File::Spec::Functions qw/no_upwards catfile/;

my $dir = "/home/porter/blue";

opendir my $dh, $dir or die "$dir: $!";
my @files = grep {-f} map {catfile $dir, $_}
	sort +no_upwards readdir $dh;
closedir $dh;

my $newname = "a";
for my $file (@files) {
	my $newfile = catfile($dir,$newname);
	print "$file -> $newfile\n"; # Debug
	move $file, $newfile or warn "$file: $!";
	$newname++;
}