In Mac OS X, a users short name is what their home folder is named after and it’s also the shorthand name for logging into the Mac either from a lock screen or a network connection with remote access through SSH and SFTP. There’s various reasons that you’d want to change the user short name, but it’s not just a matter of changing the name listed on a user account. We’ll cover four different ways to do this, a simple way that just changes the short user name for login purposes, and three more complete methods that will change not only the short user name but also the users directory name to match. Go with what is appropriate for your skill level.
It’s important to note here that spelling matters, as does capitalization, any differences in spelling or capitalization and things will not work. Do not attempt to use a short user name or account name that has spaces or special characters, keep it simple with normal characters.
Before proceeding, make sure you have a recent backup of your Mac and it’s important data. If you haven’t backed up in a while, you can force a manual backup in Time Machine easily. Once you’re backed up, read on.