Export all products id in magento

step1 : Edit the code in location app/code/core/Mage/Catalog/Model/Convert/Parser/Product.php

if (in_array($field, $this->_systemFields) || is_object($value)) {
    continue;
}

to change

if (in_array($field, $this->_systemFields) || is_object($value)) {
     if($field != "entity_id")continue;
 }

Step2: Edit the code in location

app/code/core/Mage/Adminhtml/Block/System/Convert/Gui/Edit/Tab/Wizard.php

array_splice($attributes, 0, 0, array(''=>$this->__('Choose an attribute')));

to change

$attributes["entity_id"] = "entity_id";
array_splice($attributes, 0, 0, array(''=>$this->__('Choose an attribute')));

Step3: Magento admin panel

System > Import/Export >Data profiles create profile and run profile.

PHP