Quick background: 1. For many years I had a 2006 Mac Pro which I bought used, so I set up a new user (shortname: robertcamner). Because this was a second user, it had uid=502 2. Recently, I bought a used 2010 Mac Pro which had an existing user (shortname: MacPro [yes, I know that shortnames are usually all lowercase, but this came with mixed case, and using diskutil list / I have verified that I have a case INsensitive system!]. I decided to use Migration Assistant to migrate my user from the 2006 MP to the 2010. The user MacPro has a uid of 501. 3. While the migration went smoothly, I had lots of stuff I couldn't access, both on my system volume and other volumes (including external drives), presumably because so many files had a owner uid of 502 and I didn't have a user set up on the new system with that uid. So, I created a second Admin user with exactly the same shortname (robertcamner) as on the 2006, which of course now had uid of 502, so I could access any files by logging in as this second user. OK, enough of background! This setup is not ideal...it's at best a workaround, since to access the files with the 502 user as owner I have to log in as that user. What I'd like to do is this: Have my primary user (the one with uid=501) have shortname=robertcamner (the shortname of my current 502 user) change the ownership of all files on internal and external drives to the user with uid=501 I want to to do this so I get access to all my files (wherever located) with my main user and so that my username is what I want it to be. I'm reasonably handy with Terminal, though I'm not that familiar with the various unix commands (I always have to lookup the syntax for what I want to do). So, any help with how to do this would be appreciated. I've looked at several articles about changing shortnames/usernames, but I have the added complexity that I want to make the shortname/username of the 501 user the name of the current 502 user (I don't use the 502 user except for accessing files I can't access with the 501 user). Two nagging worries: I have one real ownership oddity on my system volume. When checking which files had which owner on the system volume--using Terminal--I've discovered that the CONTENTS of the Toast Titanium.app--but not the app container itself--has the ownership set to 502, for reasons I can't fathom. See below for example of output from the find / -uid 502 command: /Applications/Toast 11 Titanium/.DS_Store /Applications/Toast 11 Titanium/Toast Titanium.app/Contents/Frameworks/AS_Storage.framework/AS_Storage /Applications/Toast 11 Titanium/Toast Titanium.app/Contents/Frameworks/AS_Storage.framework/Resources /Applications/Toast 11 Titanium/Toast Titanium.app/Contents/Frameworks/AS_Storage.framework/Versions/Current /Applications/Toast 11 Titanium/Toast Titanium.app/Contents/Frameworks/GData.framework/GData /Applications/Toast 11 Titanium/Toast Titanium.app/Contents/Frameworks/GData.framework/Resources /Applications/Toast 11 Titanium/Toast Titanium.app/Contents/Frameworks/GData.framework/Versions/Current Time Machine...Because the TM backups span the time of the migration from the 2006 to the 2010 machine, many of the backups there have ownership set to the 502 user. That hasn't caused me any headaches (yet...), but I don't know if this is something I need to worry about. Thanks in advance for your help.