push (@files,$File::Find::name) if(-f $File::Find::name);

use strict;
use Digest::MD5;
use File::Find;
use threads;
use threads::shared;
#
#
# ------------------------------------------------------------------
# get time
# ------------------------------------------------------------------
my @time        = localtime();
my $time_string = sprintf "%02d.%02d.%02d",
              $time[5]+1900, $time[4]+1, $time[3],
              $time[2], $time[1], $time[0];
#
#
# ------------------------------------------------------------------
# threads component
# ------------------------------------------------------------------
my $StopDotPrintFlag : shared;
sub DotPrintThread
  {
   my ($Interval, @Trash) = @_;
   use IO::Handle;
   autoflush STDOUT 1;
   my $IntervalCount=0;
   while ($StopDotPrintFlag != 2)
        {
         if ($StopDotPrintFlag == 1)
           {
             print STDOUT ".";
           }
         $IntervalCount++;
         sleep $Interval;
        }
         return $IntervalCount;
  }
#
#
# ------------------------------------------------------------------
# file details
# ------------------------------------------------------------------
my $directory = '.';
my $result_file = "md5_check_$time_string\.txt";
unlink ("$result_file");
#
my @files;
find(\&get_dir,$directory);
#
print "\n\tMD5_CHECK.PL powered by R.Hehlert\n";
#
#
# ------------------------------------------------------------------
# start threads
# ------------------------------------------------------------------
$StopDotPrintFlag = 0;
my $Interval = 1;
print "\n\tStarting 0% [";
my $DotPrintThread = threads->new(\&DotPrintThread, $Interval);
$StopDotPrintFlag = 1;
#
#
# ------------------------------------------------------------------
# start main programm
# ------------------------------------------------------------------
for my $file(@files)
  {
   my $md5 = Digest::MD5->new;
   open FILE, $file->[0];
   binmode(FILE);
   while (<FILE>)
        { $md5->add($_);
        }
         my $digest = $md5->hexdigest;
       close FILE;
          open(my $fh, ">>$result_file") or die $!;
          print $fh "Digest is $digest for $file->[1]\n";
          close $fh;
        }
#
#
# ------------------------------------------------------------------
# stop threads
# ------------------------------------------------------------------
$StopDotPrintFlag = 2;
my $NumberOfPrintedDots=$DotPrintThread->join;
print "\t] 100% applied time was ".$NumberOfPrintedDots*$Interval." seconds\n";
print "\n\tPls. read $result_file for results\n";
#
#
# ------------------------------------------------------------------
# get all files from all directorys
# ------------------------------------------------------------------
sub get_dir
  {
   push (@files,[$File::Find::name,$_]) if(-f $File::Find::name);
  }
#  
#END

$ perl -wle'
use File::Find;
my (@files_a, @files_b);
find(sub {
    push @files_a, $File::Find::name if -f $File::Find::name;
    push @files_b, $File::Find::name if -f $_;
}, "./testdir");
print "a: (@files_a)\nb: (@files_b)"'
a: ()
b: (./testdir/file ./testdir/sub1/file ./testdir/sub2/file)