I often get asked how to change the Home folder name (also known as the shortname). Your shortname is created when you setup your user account on your Mac. I’m afraid there is no easy way to change this on 10.6, but if you follow this tutorial you will see that it is not that hard to do when you know the steps. Luckily for 10.4 and 10.5, there is a handy application that makes this much easier, but I will talk more about that later. First let's show you how to do this in 10.6 Snow Leopard.
The first thing you need to do is enable the root user. To do this go to: /System/Library/CoreServices/Directory Utility.
Then go to the Edit > Enable Root. The first time you do this it will ask you to enter a password. Don’t forget this password. Write it down and store it somewhere safe in case you need to log in as root again later down the line.
Now Log out of the current user and log in as root user. Go to Apple menu > Log Out (your User Account Name)...
To log in as root, choose the Other… option and then for the username type root, and then use the password you created.
When you have logged in as root go to System Preferences and add a new user with the long name (Full Name) and shortname (Account Name) you wish. To create that new account, click the '+' sign on the bottom left of the Accounts window .
Make sure the shortname is the name you wish for your home folder. Here, I want to change my shortname from "soundbase" to "gary".
You’ll notice after you have created the account, that there is a folder called 'gary' under /Users (at the root level of your hard disk):
What you need to do now is rename the 'soundbase' folder to 'gary'. But first need to rename the 'gary' folder to anything else—I’ve called it 'gary2'. Don’t worry about this new name; we will be deleting this folder later. Now rename the 'soundbase' folder to 'gary'.
Next you need to change the permissions on the new 'gary' folder.
Right-click on the 'gary' folder and choose Get Info. This will bring up a dialog box with the Sharing & Permissions for the folder. Click on the padlock on the bottom right, and then click the '+' sign to add a user (as you’ll notice the 'soundbase' user is still the main user on the profile). For the new user select 'Gary' and click Select.
Now we need to change the permissions for the new user. Still under Sharing & Permissions, change the Privilege for 'gary' to 'Read & Write'.
Our last step is to apply these new permissions to the all the contents of the new home folder. Click on the Action menu (the gear icon) and choose Apply to enclosed items…
This will apply the Read & Write permissions to all the sub folders and files inside that folder.
Hang on...we’re nearly there! Log out of the root user (you can use Shift-command-Q as a shortcut). When you see the Login screen, log in as Gary.
When you log if you will get a message coming up asking about your Keychains. Just click on 'Create New Keychain'. After you're logged in, go to ~/Library/Keychains and delete the login.keychain. Mac OS X will recreate this file when you login again.
The last thing to remember is to disable root. Go back to /System/Library/CoreServices/Directory Utility, and under the Edit menu choose Disable Root User. Everything should look the same now, but your home folder should have the new shortname. You can now go and remove your previous user from the Accounts System Preferences pane. After selecting the previous account, click on the '-' sign at the bottom left of that window and choose "Delete Home Folder".
Fortunately, if you are on Mac OS 10.5 or 10.4 there is a handy application that does this for in a few seconds. At the moment there isn’t an application like this for 10.6 (and I don’t think there ever will be seeing as 10.7 is close to release.) It is very easy to use. All you do is double-click the changeshortname.dmg file. Then when the application launches you can choose which user, the new shortname and new Long Name. And that’s that! I wish it was that easy on 10.6, but afraid it's not. Let’s touch wood and hope that it will be easier to do in 10.7...
For all you 10.4 and 10.5 users out there, please don’t try and rename your home folder! This will create all sorts of havoc. When you restart your Mac, it will try and look for the original shortname folder. If OS X does not find it, it will create a new home folder with the old shortname. This means that new empty Desktop, Pictures and Music folders, etc. will be created. Not good.
Luckily in 10.6, Mac OS X doesn't allow the user to rename their home folder, which prevents this from happening.
As you can see there are a lot of steps, but if done sequentially your home folder name or shortname can be easily changed.