#!/usr/bin/perl
use strict;
use warnings;
use Date::Format;

my $delete_temp = 0;
# deleting the temp probably should be a command-line option

my $old = 'filename.html';
my $tmp = $old . '.bak';

my $date = (time2str ("%Y-%m-%d", time));
print "\n\n$date\n\n";

rename $old, $tmp or die "Cannot rename $old to $tmp: $!\n";
open my $in, '<', $tmp or die "Cannot read $tmp: $!\n";
open my $out, '>', $old or die "Cannot write to $old: $!\n";
while ( <$in> ) {
    s!(\d\d\d\d-\d\d-\d\d)(-[a-z_]{5,30}\.zip)!$date$2!g;
    # no backslash before the sigil on $date
    print $out $_;
}
close $out or die "Error writing to $old: $!\n";
close $in;

if ( $delete_temp ) {
    unlink $tmp or die "Error removing $tmp: $!\n";
}