About this question
Probably you know System Administrator profile, if you try to migrate change to object or field or page or application or class permissions for the profile and you try to retrieve it, you will get an error.
Entity of type 'Profile' named 'System Administrator' cannot be found
However, if you retrieve all profiles, you might find 'Admin.profile' which looks like matching to System Administrator profile. How to match profile names? On Profile Standard object there is no field exposed containing 'Admin'. There is another profile called 'StandardAul.profile' amongst the ANT metadata files. I try hard to guess which profile it matches. Does it match to Standard Platform profile? Is there any general way to match Salesforce profile name (visible on Web Interface, in Developer Console) and if you query for it by SOQL query:
[select Id, Name, Description from Profile]to ANT Metadata File name? Retrieving package.xml containing: