Glossary of Terms

Term	Definition
Arizona	Arizona is the name of one of Princeton's Unix clusters. It is a group of machines which anyone with a Princeton ID can log onto using programs like SSH. We will be using the Arizona cluster during this lab.
`cd`	A Unix command that changes the current directory. Typing `cd cos109` will move you into the directory you created during this lab. To get back to your home directory, type cd by itself. You can also type `cd ..` to move up one level in the file system, and you can type `pwd` to print the name of the directory you are working in.
Cookies	Cookies are small files containing text. They are left by web servers which you visit using a web browser. A cookie stores information specific to one site, typically a number that can be used to identify you when you visit the site again.
Desktop	The Desktop is the name for a folder that holds all the files corresponding to the icons on your screen. It differs from other folders in that its contents are displayed as icons.
Directory	A directory is the Unix equivalent of a folder: a place where files can be stored and organized. Unix directories are navigated using the `cd`, or change directory, command.
Double-Click	Press the left mouse button twice in rapid succession.
Executable Program	A program is a file that contains the instructions that tell the computer what to do to perform some task; running the program is called "execution", so the file is often called an "executable". Internet Explorer and Microsoft Word are two examples of executable programs. When they are launched they tell the computer respectively to load your homepage, and to bring up a new window for you to type in. In Windows, programs are usually started by double-clicking on them; in Unix they are usually started by typing their name.
File System	A file system is how the operating system organizes all the data that is stored on the computer, in a form that is convenient for users to save information, organize it, and retrieve it as needed.
Folder	A folder is the Windows equivalent of a Unix directory. A folder is a place where files can be stored and organized. Windows folders are usually navigated by double-clicking on them, often with Windows Explorer.
Icons	Icons are small pictures that some operating systems use to represent files and folders to users in a way that makes them easy to recognize visually.
Linux	Linux is a non-proprietary Unix variant, created and supported by volunteers, which anyone can modify and redistribute freely.
`ls`	A Unix command that lists the contents of a directory; you can get more information with the command `ls -l`. (That's "minus ell", not minus one"; some fonts don't distinguish these as clearly as they should.) The `ls` command is the keyboard equivalent of Explorer.
`mkdir`	A Unix command that makes a new directory. Type, for example, `mkdir cos109` to make the directory `cos109`.
`mv`	A Unix command that renames a file; it is often used to move a file from one directory to another. Typing `mv file new_location` will move the file to the new location, in effect renaming it.
Operating System	An operating system is a program that manages the resources of a computer for you. It lets you run programs like browsers and word processors and Kazaa; it lets you store and retrieve information on disks; it lets you use peripheral devices like printers, keyboards, and speakers; and it lets you communicate with other machines via a network.
Pine	Pine is a text-based Unix email program. It lets you read your mail, and compose new mail on Unix.
Prompt	The Unix prompt, or command prompt, is a short string of characters which tells the user that the computer is ready to accept new input. On the Arizona clusters the prompt looks something like this: flagstaff.Princeton.EDU%.
Right-Click	Press the right mouse button once.
SSH	SSH stands for Secure Shell. It is a program that allows you to connect to computers in other locations and use them as if you were sitting in front of them. It uses encryption to prevent anyone else from intercepting your communications and stealing information such as your password.
Start Menu	The start menu is a menu in Windows which normally resides in the lower left hand corner of the screen. It is a starting point for doing such tasks as launching programs or searching for files.
Taskbar	The taskbar is the bar where Windows displays running programs and open files. It is a long gray bar which normally sits at the bottom of the screen. The taskbar also holds the start menu.
Telnet	Telnet is a program that allows you to connect to computers in other locations and use them as if you were sitting in front of them. Unlike SSH, Telnet does not encrypt your information before it sends it to the remote machine. Therefore anyone is free to intercept the communication.
Unix	Unix is a widely-used operating system. It is used by many web sites and services which you use every day.
Username	Your username is the name which you use to log onto Princeton computers. More generally it is any name which identifies you to a computer system. To log onto any Princeton machine you must enter your username and your password.
`who`	A Unix command that tells you who else is logged into the same computer as you are. One major difference between Unix and Windows is that Unix supports multiple users running on the same computer at the same time.
Windows	Windows is an operating system written by Microsoft. It is the predominant consumer operating system, and the one we'll be using for the first half of this lab.