my $dir = '.';

opendir my $dirh, $dir or die $!;
my @files = grep{ -f $dir . '/' . $_ }readdir $dirh;
closedir $dirh;

# nach modification time sortiert
# sogenannte Schwartz'sche Transformation
my @sorted_files = map{ $_->[0] }
                         sort{ $a->[1] <=> $b->[1] }  
                         map{ [$_, -M $dir . '/' . $_] }@files;

print $_,"\n" for @sorted_files;