Start a Terminal Session
The application Terminal is your interface to the BSD layer of you Macintosh. In the Finder, simply start from your Applications folder, and you’ll find Terminal here:
Double-click it, and when it starts, it will look something like this:
The message Welcome to Darwin is simply Mac OS X’s way of saying hello. But [localhost:~] tells you that you are logged into your local machine, localhost, and the current working directory is ~, which is the home directory of whatever current user that you are. For example, my home directory on the system is /Users/~jderry, and ~ is an automatic shortcut to that directory. If I were to type cd /Applications, the terminal would prompt me with [localhost:/Applications]. Finally, the jderry% tells you what user you currently are.