my $x=0;
for (my$a=0; $a<10; $a++)
{
   open (file);
   while <my $line = file>
   {
      $x++;
      if ($x==1)
      {
         print $header, "\n";
         (@keys) = split (/\t/, $line);
      }
      else
      {
         *Does some filtering as each line is read in*
      }
   }
}