Laboratory: Getting Started in the MathLAN

Summary: This lab reviews some mechanics related to the use of the Mathematics Local-Area Network (MathLAN) for CSC 151. Specifically, this lab discusses:

• Logging In
• The Linux/Gnome Window Environment
• Practice with a Terminal Window: Changing Your Password
• Mozilla
  • Mozilla Options
  • Mozilla as an Email Client
    • Setting Mail Preferences
    • Getting Mail
• Finishing Up and Logging Out

Please don't be intimidated! Although this lab contains many details which may seem overwhelming at first, these mechanics will become familiar rather quickly. To help the process along, you might want to spend some time on your own before the next class, working through the lab a few times, exploring various buttons, and experimenting with options. Feel free to talk to the instructor or with a MathLAN User Consultant if you have questions or want additional help!

Logging In

To use any of the computers in the Mathematics Local-Area Network, one must log in, identifying oneself by giving a user name and a password. You will have received a MathLAN user name and password from the instructor if you did not already have one. If you have not received a MathLAN user name and password, or if you have forgotten either one, please tell your instructor.

When it is not in use, a MathLAN workstation displays a login screen with a space into which one can type one's user name and, later, one's password. (If the workstation's monitor is dark, move the mouse a bit and the login screen will appear.) To begin, move the mouse onto any part of the box containing the login box. Type in your user name, in lower-case letters, and press the <Enter> key. The login screen will be redrawn to acknowledge your user name and to ask for your password; type it into the space provided and press <Enter>. (Because no one else should see your password, it is not displayed on screen as you type it in.)

At this point, a computer program that is running on the workstation consults a table of valid user names and passwords. If it does not find the particular combination that you have supplied, it prints a brief message saying that the attempt to log in was unsuccessful and then returns to the login screen -- inviting you to try again. Consult the instructor or the system administrator if your attempts to log in are still unsuccessful.

The Linux/Gnome Window Environment

Once you have logged in, a control panel will appear at the bottom of the screen. Some other windows also may be visible in other parts of your screen. All of these areas are managed by a special program, called a windowing system. On MathLAN, login chores and other administrivia are handled by a program or operating system, called Linux, and the windowing system is called Gnome. (While the Linux operating system supports many languages and environments, you may be interested to know that the Linux/Gnome windowing system itself is written in Scheme.)

Practice with a Terminal Window: Changing Your Password

While we can run several programs directly, we will need to invoke others by name. The computer program that reads and responds to such invocations is called the shell, and your interactions with the shell takes place in a window generated by a program called a terminal emulator, or terminal for short.

You may already have a Terminal window on screen. If not, you can start one at any time by moving the pointer onto the small monitor icon at the bottom middle of the front panel, and clicking with the left mouse button. Shortly a window appears, displaying the shell prompt -- the name of the workstation on which the shell is running, followed by a percentage sign. This prompt indicates that the shell is ready to receive instructions.

You type in such instructions using the keyboard. Move the mouse pointer into the Terminal window and click the left mouse button to make the window active. Notice that the window frame changes color following the click, indicating that the window has become active.

To shut down the Terminalwindow, press <Ctrl/D>. That is, hold down either of the keys marked <Ctrl>, just below the <Shift> keys, and simultaneously press the <D> key. (On our workstations' keyboards, the keys marked <Ctrl> (control) and <Alt> (alt or meta) are somewhat like <Shift> keys, in the sense that they modify the effect of other keys that are pressed simultaneously.) The shell program interprets <Ctrl/D> as a signal that you have no more instructions for it and halts, and the terminal emulator closes the window automatically once the shell stops running. Alternatively, you may close a window by moving the mouse to the x at the top-right of the window, and clicking the right mouse button. Finally, you can usually type exit to colose a terminal window.

It is a good idea to change the password associated with your account shortly after you receive it and every few months thereafter. The program that one uses to change one's password is also invoked by its name, password.

Choose a new password. Make it something that you can easily remember, but not an English word or a name, since it is easy for system crackers to break in by guessing your password if you choose it from one of those categories.

Open a terminal window, select the window by clicking the left mouse button in it, and type the word password. The password program prompts you once for your old password -- the one you logged in with -- and twice for your new password. If you give your old password correctly and the two copies of your new password match, the program substitutes the new password for the old one in the table that the login program consults. The old password is discarded and will not be recognized in subsequent logins. (If the attempt to change the password fails for any reason, however, the old password is retained.)

A typical interaction to successfully change a password looks like this:

   bourbaki% password
   Changing NIS account information for user on hopper.math.grin.edu.
   Please enter old password:
   Changing NIS password for user on hopper.math.grin.edu.
   Please enter new password:
   Please retype new password:

   The NIS password has been changed on hopper.math.grin.edu.

   bourbaki% 

After running the password program, the shell takes over again and issues another prompt. You can invoke as many programs as you like from the shell, one after another, before pressing <Ctrl/D> or exit to leave the shell.

Mozilla

Almost all of the materials for this course will be distributed over the World Wide Web rather than in paper copies. To view materials, such as this course's syllabus and this lab, you may follow these steps:

First, prepare to use the World Wide Web by clicking on the Mozilla icon (the picture with the Red Dragon at the bottom panel of the screen). The first time you run Mozilla on MathLAN, two message boxes might appear.

• One box might ask you to consent to the terms of a licensing agreement.
• One box might requiest permission to create some configuration files in your home directory.

You should approve of any requests by clicking on the appropriate word. The pop-up boxes then disappear; you won't see them on subsequent uses of Mozilla.

Initially, Mozilla displays a World Wide Web document containing some default information (the last time I checked, it was information on Red Hat Linux). You should switch to the page http://www.cs.grinnell.edu/origin.html, which is an entry point to the Mathematics and Computer Science Department's Web site.

I expect that most of your are already familiar with a Web browser. If not, please consult with me or one of your colleagues.

To find material for this course, scroll down the origin page for the Mathematics and Computer Science Department, click on the line Computer Science and Mathematics Courses; this takes you to the department's home page. Now scroll down this page to find the entry for this course, Fundamentals of Computer Science I, Section 1, and click on it to locate the front door for this course. Next, click on the Glance link to view the current draft of the semester's schedule. If you click on the Current link, you'll see an outline of today's class.

You can also connect to the Web page for this class by selecting Open Web Location from the File menu and then entering http://www.cs.grinnell.edu/~rebelsky/Courses/CS151/2002F/

Mozilla Options

Each MathLAN user can configure Mozilla to reflect her or his own preferences. Between logins, these preferences are stored in a file in the user's home directory; when mozilla is started during a later session, they are reinstated from that file.

Every user of Mozilla on MathLAN should establish a base page, a starting point for browsing. Here are the Uniform Resource Locators or URLs of some good choices:

• The front-door for this course: http://www.cs.grinnell.edu/~rebelsky/Courses/CS151/2002F/.
• The departmental origin http://www.math.grin.edu/origin.html
• Grinnell College's front-door page (oh boy!) http://www.grinnell.edu
• WebMail http://webmail.grinnell.ed
• A page you create.

To establish your base page, within Mozilla, bring up the Edit menu from the menu bar and select the Preferences operation. A pop-up window appears, allowing you to configure many features of the general appearance of Mozilla. Choose the Navigator option. The rectangle labeled Home Page Location contains the URL of the Welcome to Mozilla document at Mozilla Communications Corporation; this is what Mozilla uses by default as a base page. Replace the contents of this rectangle with one of the URLs shown above. (This does not have to be a permanent change; you can change your mind about this configuration at any time within Mozilla.)

To erase the current contents of the Home Page Location box, move the mouse pointer to the left of the first character in the box, press the left mouse button and hold it down, and drag the mouse pointer rightwards until the entire URL is displayed in reverse video, white letters on a black background. Then release the left mouse button and type the new URL; the old one will vanish as soon as you start typing. Once you have entered the new URL, move the mouse pointer onto the button marked OK at the bottom of the pop-up window and click on it with the left mouse button.

Mozilla as an Email Client

While you probably use WebMail (blech) for most of your email, you can also use Mozilla (at least when it's configured right). So that you can send email appropriately within the MathLAN, I'd like you to configure Mozilla as a mail client. This lets you use the mailto links that sometimes appear in pages.

Setting Mail Preferences

1. Select Mail & Newsgroups from under the Tasks menu. An Account Wizard window should appear. The wizard begins by asking you what you want to do
2. Click on Email Account.
3. Click on Next >. The wizard will now ask for some basic information about you.
4. In the box labeled Your Name, enter your name.
5. In the box labeled Email Address, enter your standard Grinnell email address (i.e., username@grinnell.edu).
6. Click on Next >. The wizard will now ask about your email servers.
7. Click on IMAP.
8. Enter mail.grinnell.edu for the Incoming Server Name.
9. Enter smtp.grinnell.edu for the Outgoing Server (SMTP) Name.
10. Click on Next >. The wizard will ask about your user name.
11. Enter your user name in the box.
12. Click on Next >. The wizard will ask for a name to refer to this account. I'd recommend leaving the recommended value.
13. Click on Next >.
14. Click on Finish. The wizard will finish and you will then be prompted for your email password. Enter it.

Getting Mail

Spend a few minutes getting acclimated. Try to send at least one message (e.g., to me). Spend no more than five minutes reading email.

In the future, you can access the Mozilla Mail application by selecting Mail & Newsgroups from under the Communicator menu.

Finishing Up and Logging Out

If you've successfully logged in, changed your password, started Mozilla, selected your base page, configured Mozilla for email, and sent me a sample email, you've completed this part of the lab.

When you are done using a workstation, you must log out in order to allow other people to use it. To log out, move the pointer onto the footprint icon near the left of the front panel, click the left mouse button, and select the Log out option. A confirmation box will pop up, asking you to verify that you're ready to log out; move the pointer onto the word Yes near the bottom of this box and click the left mouse button. The Gnome windowing system vanishes, and after a few seconds the login screen reappears; this confirms that you're really logged out.

Please do not turn off the workstation when you are finished. MathLAN workstations are designed to operate continuously; turning them off and on frequently actually shortens their life expectancy.