#!/usr/bin/env perl

# words - list all words (a-zA-Z0-9 only) in the input, translated to lowercase
#
# $Id: words 771 2010-10-15 10:14:31Z rp $

# -x for extended filtering (i.e., fewer words)

use warnings;
use strict;

use Getopt::Std;

my %opt; getopts('ux', \%opt);

$| = !!$opt{u};  # if -u, flush after every line

my $rx = $opt{x} ? qr/[\W\d]/ : qr/\W/;

while (<>)
{
  chomp;
  map { length and print "\L$_\n" } split /$rx/;
}