<?php 
 
include_once './app/Mage.php'; 
Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID); 
 
$updates_file = "./var/export/sku2sku.csv"; 
$sku_entry = array(); 
$updates_handle = fopen($updates_file, 'r'); 
if($updates_handle) { 
    while($sku_entry=fgetcsv($updates_handle, 1000, ",")) { 
        $old_sku = $sku_entry[0]; 
        $new_sku = $sku_entry[1]; 
        echo "<br>Updating " . $old_sku . " to " . $new_sku . " - "; 
        try { 
            $get_item = Mage::getModel('catalog/product')->loadByAttribute('sku', $old_sku); 
            if ($get_item) { 
                $get_item->setSku($new_sku)->save(); 
                echo "successful"; 
            } else { 
                echo "item not found"; 
            } 
        } catch (Exception $e) { 
            echo "Cannot retrieve products from Magento: " . $e->getMessage()."<br>"; 
            return; 
        } 
    } 
} 
fclose($updates_handle); 
 
 |