<?php
header('Content-Type: text/html; charset=utf-8');
$c =4;
echo '<pre>';
if($f = fopen("file.txt","r")){
 while (!feof($f)){
  do{
    $m[] = fgets($f);
  }while(!feof($f) && count($m) < $c);
  // action
  print_r($m);
  unset($m);
  echo '<hr />';
 }
 fclose($f);
}
echo '</pre>';
?>

        $i = 0;
        do {
            $line = fgets($handle);
            if (empty($line)) {
                echo 'last batch';
                //action
                return;
            }
            if ($i == 10) {
                //action
                unset($batch);
                $batch = array();
                $i=0;
            }
            $batch[] = trim($line);
            $i++;

        } while ($line);