I have created cron for my custom module using this link http://devdocs.magento.com/guides/v2.0/config-guide/cron/custom-cron-ref.html
crontab.xml
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Cron:etc/crontab.xsd">
<group id="test">
<job name="test" instance="test\Ship\Cron\Observer" method="cronOderSync">
<schedule>*/5 * * * *</schedule>
</job>
</group>
</config>
And cron_groups.xml
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Cron:etc/cron_groups.xsd">
<group id="test">
<schedule_generate_every>5</schedule_generate_every>
<schedule_ahead_for>4</schedule_ahead_for>
<schedule_lifetime>4</schedule_lifetime>
<history_cleanup_every>10</history_cleanup_every>
<history_success_lifetime>60</history_success_lifetime>
<history_failure_lifetime>600</history_failure_lifetime>
<use_separate_process>1</use_separate_process>
</group>
</config>
So I have two issues:
1) when I run bin/magento cron:run [--group="<cron group name>"], it run all crons file.
2) I have setup schedule in cron_group.xml file, but it did not run cron every 5 minutes automatically.