[widebody911]

Use perl readdir structure to loop thru the files, for each file grab the fstat (File::stat) structure to get the timestamp, then copy the new file using a new index counter.

hacked-out psuedocode off the top of my head

use File::copy;
use File::stat;
use Time::locatime;

$new_index=1;
opendir(DIR, "your/data/directory") || die "ooops!"
foreach my $old_file (readdir(DIR)) {
   my $time = ctime(stat($old_file)->mtime);
  next if ($time outside my range) # you have to work out this bit
  
  copy ("$old_file", "file.$new_index)
   $new_index++;
}
close(dir);