my $dir='/irgendwo/im/dateisystem';
opendir(my $dh, $dir) or die("Error open $dir $!\n");
my @files=grep{-f "$dir/$_"}readdir($dh);
closedir($dh);
# Schwarzsche Transformation
# name -> [mdate,name] -> sort() -> name
@files=map{$_->[1]}sort{$a->[0] <=> $b->[0]}map{[-M "$dir/$_",$_]}@files;
for my $file (@files)
{
  # mach was mit den sortierten Namen.
}