Gists for federivo.github.io/magento2/2016/02/19/commands-in-magento2.html

di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Framework\Console\CommandList">
        <arguments>
            <argument name="commands" xsi:type="array">
                <item name="exportCustomersCommand" xsi:type="object">Federivo\CustomerExport\Command\ExportCustomerCommand</item>
            </argument>
        </arguments>
    </type>
</config>

module.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Federivo_CustomerExport" setup_version="0.0.1" />
</config>