I recently installed Oh-my-Zsh on a new Macbook Pro running Mountain Lion. When I opened up my terminal, I received the message “ComputerName: not set”.

I tried to use the ‘sudo hostname’ command, but this didn’t seem to work. I ended up opening System Preferences -> Sharing, and then set my Computer Name.

I found an article that also suggested using the following:

sudo scutil --set ComputerName "newname"
sudo scutil --set LocalHostName "newname"
sudo scutil --set HostName "newname"