Open source perl auto-updater for <lastmod> in XML sitemaps.

autodate.pl

#!/usr/bin/perl

#######################################################################
#Basic perl script to update <lastmod> in an XML sitemap.             #
#Works by seaching for .html files nested in <loc> and then comparing #
#to the file. It then inserts the date in the <lastmod> tag.          #
#                                                                     #
#This code is not subject to copyright and is free to use             #
#                                                                     #
#Eliot Brown 25/10/2011                                               #
#Version 1.05                                                         #
#######################################################################

use warnings;
use strict;
use POSIX;

chdir('/home/eliot/Ubuntu One/YEAR 1 University/Programming/XHTML') or die "$!";
  
my $lastmod;
my @html_files;
foreach (<*\.html>) {
	push @html_files, $_.strftime("%Y-%m-%dT%H:%M:%S+00:00", localtime((stat($_))[9]));
}
    
my $old = "sitemap.xml";
my $old_orig = "sitemap_orig.xml";
my $new = "sitemap_new.xml";
   
open (OLD, "< $old") or die "Can't open $old: $!";
open (NEW, "> $new") or die "Can't open $new: $!";
select(NEW);   # new default filehandle
while (<OLD>) {
# process line, change $_ if required and then print to NEW filehandle
	if (/<loc>(.*?)<\/loc>/ and grep {/^$1/} @html_files) {
		$lastmod = (grep {/^$1/} @html_files)[0];
	    $lastmod =~ s/^$1//;
    } elsif (/<lastmod>(.*?)<\/lastmod>/ and $lastmod ne "") {
		$_ = "<lastmod>$lastmod<\/lastmod>\n";
		$lastmod = "";
	}
    print NEW $_;
}
close (OLD) or die "Can't close $old: $!";
close (NEW) or die "Can't close $new: $!";
rename($old, $old_orig) or die "Can't rename $old to $old_orig: $!";
rename($new, $old) or die "Can't rename $new to $old: $!";