Where Am I?
When working in a Unix shell, you are always located at a specific branching point--in a specific directory in the file tree.   Every directory ends with the character '/', so the name of the root directory is simply '/', and for every directory you pass through down the file tree, there will be another '/' in the filename.

To find out what directory you are currently working in, you type:
    > pwd

This command stands for "print working directory".  When you first login to Linux, your working directory will be what is called your "home directory"--for each person at CCRMA, this directory is  "/user/firstInitialOfLoginName/LoginName/".   My home directory is thus "/user/r/randal/".     Because typing its pathname is so common, the home directory may be abbreviated as "~LoginName/"  or simply "~/".       Notice now that when you first login, the prompt in each of the shells is in the form "[NameOfComputer  LoginName]  ~>".    The "~" before the prompt means that you are working in your home directory.  If you change directories, using the commands I will soon explain, the "~" will be changed to the name of your current working directory.