#!/usr/bin/perl -w
# You can alternatively just do:  
# find . -xdev -type f -print0 | xargs -r0 ls -l | sort -rn +4 | head -20
use File::Find;

@ARGV = $ENV{ PWD } unless @ARGV;
find ( sub { $size{ $File::Find::name } = -s if -f; }, @ARGV );
@sorted = sort { $size{ $b } <=> $size{ $a } } keys %size;
splice @sorted, 20 if @sorted > 20;
printf "%10d %s\n", $size{$_}, $_ for @sorted