Set or Change Hostname (via the GUI)
- Open System Preferences
- Select Sharing
Select the Edit button and enter your desired Local Hostname and click OK
Note: If the Edit button is greyed out, click on the Lock Icon, authenticate with an admin account
Set or Change Hostname (via Terminal) - OS X Mavericks or newer
- Open Terminal by going to Applications, then Utilities, and select Terminal
The the following: