#!/usr/bin/perl -w
use strict;
use XML::LibXML;

my $file = $ARGV[0] || die "Usage: $0 [uri|filename]\n";
my $doc = XML::LibXML->new->parse_html_file($file);
print "Alt tags in $file:\n";
foreach my $alt ($doc->findnodes('//img/@alt')) {
  print "Alt tag: ", $alt->nodeValue, "\n";
}
print "Done\n";