You can search and filter resources based on the tags you use. For example, you can list a Eucalyptus Machine Image (EMI) using euca-describe-images, and you can list instances using euca-describe-instances .
Results from describe commands can be long. Use a filter to include only the resources that match certain criteria. For example, you can filter so that a returned list shows only the EMIs that use an EBS volume as the root device volumes.
Filtering also allows you to:
In each case, the instance must match all your filters to be included in the results. Filter values are case sensitive.