#!/usr/bin/env perl

use strict;
use warnings;
use POSIX qw (strftime);
use Path::Iterator::Rule;
use Image::ExifTool;

my $dir = q(./pdf);
my $tz = strftime( "%z", localtime() );
# my $tz = strftime( "%z", gmtime() );

$tz =~ s/(\d{2})$/':$1'/;

my $rule = Path::Iterator::Rule->new;

# $rule->file('*.pdf'); # :-(
$rule->file->name(qr/.+\.pdf/);
$rule->max_depth(1);

my $next = $rule->iter($dir);

while ( defined( my $file = $next->() ) ) {
    my $mtime = ( stat($file) )[9];
    my $atime = ( stat($file) )[8];
    my ( $m_sec, $m_min, $m_hour, $m_day, $m_month, $m_year ) =
      ( localtime($mtime) )[ 0, 1, 2, 3, 4, 5 ];
      # ( gmtime($mtime) )[ 0, 1, 2, 3, 4, 5 ];

    $m_year += 1900;

    my $m_timestamp = sprintf( "%4d:%02d:%02d %02d:%02d:%02d",
        $m_year, $m_month, $m_day, $m_hour, $m_min, $m_sec );

    $m_timestamp .= $tz;

    my $exifTool = Image::ExifTool->new();

    $exifTool->SetNewValue( "ModifyDate", $m_timestamp );
    $exifTool->SetNewValue( "CreateDate", $m_timestamp );
    $exifTool->WriteInfo($file);
    utime $atime, $mtime, $file;
}

__END__

##</code><code>##

karls-mac-mini:monks karl$ perl -MImage::ExifTool=:Public -E 'say ImageInfo("./pdf/a.pdf")->{CreateDate};'
2015:01:07 14:46:51
karls-mac-mini:monks karl$ ls -hl ./pdf/a.pdf 
-rw-r--r--  1 karl  karl    48K  7 Feb 14:46 ./pdf/a.pdf

##</code><code>##

#!/usr/bin/env perl

use strict;
use warnings;
use POSIX qw (strftime);
use Path::Iterator::Rule;
use Image::ExifTool;

my $dir = q(./pdf);
my $rule = Path::Iterator::Rule->new;

# $rule->file('*.pdf'); # :-(
$rule->file->name(qr/.+\.pdf/);
$rule->max_depth(1);

my $next = $rule->iter($dir);

while ( defined( my $file = $next->() ) ) {
    my $mtime       = ( stat($file) )[9];
    my $atime       = ( stat($file) )[8];
    my $m_timestamp = strftime( "%Y:%m:%d %H:%M:%S%z", localtime($mtime) );
    my $exifTool = Image::ExifTool->new();                                               
    $exifTool->SetNewValue( "ModifyDate", $m_timestamp );
    $exifTool->SetNewValue( "CreateDate", $m_timestamp );
    $exifTool->WriteInfo($file);
    utime $atime, $mtime, $file;
}

__END__