get_category_by_ids.php

  require_once 'app/Mage.php';
  Mage::app();
  
  function getCategoryIdByName($categoryName) {
    $category = Mage::getResourceModel("catalog/category_collection")->addFieldToFilter("name" , $categoryName);
    $cat_det=$category->getData();
    $category_id=$cat_det[0][entity_id];
    return $category_id;
  }
  $dir = new DirectoryIterator("./getbyname");
  foreach ($dir as $fileinfo) {
      if (!$fileinfo->isDot()) {
          $fname = $fileinfo->getFilename();
          $basefname = basename($fname, ".csv"); 
          $parentId = intVal($fname);
          $fp = fopen("./getbyname/" . $fname, "r");
          $fpwrite = fopen("results.csv", "w");
          while($line = fgetcsv($fp)) {
              $categoryName = $line[0];
              $ogName = $line[1];
              $id = getCategoryIdByName($categoryName);

              $fields = array($ogName, $id);
              fputcsv($fpwrite, $fields);
              echo $categoryName . ", " . $ogName . ", " . $id . "\n";
          }
          fclose($fp);
          fclose($fpwrite);
      }
  }