export_products_importexport.php

<?php
/**
 * Runs export via Import/Export module
 */
require __DIR__ . '/app/Mage.php';

// disable flat products collection
Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);
Mage::app()->getLayout()->setArea('adminhtml');

/** @var $model Mage_ImportExport_Model_Export */
$model = Mage::getModel('importexport/export');
$model->setData(array(
    'entity' => 'catalog_product',
    'file_format' => 'csv',
    'export_filter' => array(),
));

print "Starting export...\n";

$content = $model->export();
$type = $model->getContentType();

print "Export done, writing to file...\n";

file_put_contents($model->getFileName(), $content);

print 'Done, memory ' . number_format(memory_get_peak_usage(true)) . " bytes.\n";
return 0;