#!/usr/bin/env perl
use strict;
use warnings;
my $exe= '/usr/bin/exiftime';
#my $exe= '/usr/bin/exiftags -v';
foreach my $file (@ARGV){
  if (-e $file && $file =~ /\.(jpg|JPG)$/){
    my ($exif)=grep(/Image (Created|Generated|Digitized):/,`$exe $file`);
    if ($exif && $exif=~s/^Image .*?: (.*)//){;
      my ($y,$m,$d,$h,$M,$s)=split(/[: ]/,$1);
      my $new=sprintf "%04d%02d%02d_%02d%02d%02d",$y,$m,$d,$h,$M,$s;
      my ($ext) = map{ /.*\.(.*)/ } ($file);
      $new .= ".$ext" if($ext);
      if ($file ne $new && !-e $new){
        printf "$file -> $new\n";
        rename $file,$new;
      }
    }
  }
}