1. A method to centralize identity management, the method comprising: retrieving locally managed user identities for a plurality of users of Unix from at least one server; merging with one or more computer processors the locally managed user identities for the plurality of users of Unix with centrally managed identities associated with a plurality of users of Active Directory according to a plurality of rules wherein the merged locally managed user identities and the centrally managed user identities comprise unique identities and at least a plurality of non-unique identities, the non-unique identities comprising user identities that have the same identifier for at least two different users from two distinct domains; performing an identity conflict check of the merged locally managed user identities and the centrally managed user identities to identify conflicts associated with the non-unique identities; when conflicts are identified, unmerging the merged locally managed user identities causing the conflicts from the centrally managed user identities prior to migrating the merged locally managed user identities to the centrally managed user identities; when conflicts do not exist, creating an identity map with one or more computer processors that maps the merged locally managed user identities associated with Unix to the centrally managed user identities associated with Active Directory prior to migrating the merged locally managed user identities to the centrally managed user identities; communicating the identity map to the at least one server; and migrating the merged locally managed user identities associated with Unix to the centrally located user identities associated with Active Directory based on the identity map; reassigning resources of the merged locally managed user identities to the centrally managed user identities in accordance with the identity map, wherein the resources comprise at least administrative privileges for the locally managed user identities; and storing rollback information to enable rollback of the migration of the merged locally managed user identities from the centrally managed user identities and rollback of the reassigned resources.