The goal of this lab session is to introduce you to:

• Computers: In particular, Dell PCs.
• The Linux Operating System: The operating system (OS) is the interface between you and the machine, and allows you to give instructions to the machine. The OS we are running Ubuntu 10.04 (aka Lucid Lynx)/Linux.
• zsh: The Z shell; a command interpreter used to pass user commands to the OS.
• The vi Text Editor: A text editor allows you to enter information or data into the machine and allows you to store, retrieve, and edit that information.
• Programs: "A set of explicit and unambiguous instructions expressed in a programming language," from How to Solve It by Computer, page 1, by R. G. Dromey.
• Program Compilation and Execution (i.e., running a program): The compiler we use is g++.

Important: Attendance is required at all labs. If you leave early, you must submit your files before you leave.

Important: Failure to do a lab, to submit your work on time, or to make a proper attempt on any part of the lab may result in a grade reduction. Take the labs seriously; we do. Good work will be rewarded. Please, do your own work.

1.  Logging in for the First Time

1. When you logged on, the machine launched the window manager. Your panel (at the top) and Applications button (at the top, left) appeared.
2. The Applications menu. At the top, left corner of your screen is a button with the Ubuntu icon and the word Applications. Click on this button to reveal a large menu with many submenus and more buttons. Clicking one of these buttons will launch that Application; passing your mouse cursor over one of the submenus will reveal the buttons within that submenu.
3. The Panel. Across the top of your screen there is a gray bar or Panel that holds the buttons to your Applications menu and other menus. The Panel can also hold launcher buttons for quick access to launch frequently used Applications.
4. We will perform most tasks in a terminal window. To launch the Z shell terminal, click the Applications button at the top, left of the Ubuntu desktop, mouse over Accessories, and click Terminal. Using two Terminals allows you to edit your code in one terminal and test or execute that same code in the other Terminal. Open two terminals now. Note that when your terminal opens, you are in your home (upper level) directory.
5. Since we will be using the terminal frequently, we want to pin it to the panel for quick access. Click the Applications button at the top, left of the Ubuntu desktop, mouse over Accessories, right-click Terminal, and left-click "Add this launcher to panel".
6. Changing your Password. To change your password, type utkcs-passwd, press Enter and follow the instructions. If you want to read more about passwords, click here.

2.  Learning the Operating System -- Some Linux Commands

1. ls   This command is stands for "list files." Information is stored in files that are organized into directories, which are simply collections of files. List the contents of your current directory with the command ls.

   ls -l   stands for "list long" and lists the contents of a directory in more detail. The -l is called a switch, and many Linux commands have switches that modify the command's behavior.

2. c   When you want a clean screen, enter the command clear (or c for short).

3. mkdir  This command stands for "make directory." You must do your work in the appropriate directory (a special kind of file) for each lab. This directory is like an electronic file drawer where you will place the files you create during lab. Create your Lab1 directory now by issuing these commands:
   • mkdir cs102
   • cd cs102
   • mkdir Lab1

   The ~ (tilde) is shorthand for your home directory, and ~/cs102 refers to the cs102 subdirectory of your home directory. Omitting ~/cs102/ will work just as well if you are already in your cs102 subdirectory.  ~/cs102 is called a path; it tells where the file Lab1 is.

   Now type ls ~/cs102 (or ls cs102) to see the contents of your cs102 subdirectory. Notice that ls lists a ~/cs102/Lab1 directory, displayed as Lab1/. The slash (/) indicates that file Lab1 is a directory; the slash is not part of the file name. Below cs102 you will create a directory for each lab.

4. cd  This command stands for "change directory." To change to your ~/cs102/Lab1 subdirectory in any particular window, type one of the following commands:
   cd ~/cs102/Lab1     -OR-     cd cs102/Lab1

   You are changing to the Lab1 subdirectory of the cs102 subdirectory of your home directory. Notice the change in the Linux prompt. The command cd without a path name puts you in your home (upper level) directory. The command cd ..   moves you up one level in the directory tree.

5. pwd  This command stands for "print the working directory." When you enter this command, you should see output that is similar to the following...
   /home/username/cs102/Lab1

   ...but with your username listed is place of "username." This path name ends with the name of the current directory, Lab1 (Your Linux prompt indicates where you are without your having to use the pwd command. This is something we have done for you; it is not a standard Linux feature).

   Move the cursor to a different window and activate it. Type pwd into the different window and compare the result to that in the first window. Note that the working directories are not the same. Changing directories in one window does not change directory in any other window. Change to your Lab1 subdirectory in all windows now.

6. cp  This command stands for "copy" and is used for copying files. In order to copy files from the CS 102 management account into your Lab1 directory, enter the following command in any window:
   cp   ~cs102/robot_labs/Lab_Skeletons/Lab1/*   ~/cs102/Lab1

   ~cs102 refers to the home directory of the CS 102 management account, and Lab1 is a subdirectory in the cs102 account. The asterisk is a wildcard and means all the files. Thus, each file from the ~cs102/Lab1 directory is copied to your ~/cs102/Lab1 directory. The file names are the same.

   In English, the cp command above says, "Copy all the files from the Lab1 subdirectory of the cs102 home directory into my cs102/Lab1 subdirectory." Notice the presence (or absence) of the slash character after the tildes:

   • ~cs102 refers to the home directory of user cs102.
     
   • ~/cs102 refers to the cs102 subdirectory of your home directory.

7. List files again   List the contents of your current directory by typing ls. You should see several new file names listed that you have just copied. If not, please ask a TA for help now.

8. less  Now you will learn less, a Linux command for browsing files. Activate a smaller window and type
   less README

   to browse the README file. In long files, move from page to page by hitting the space bar, and move back a page by hitting b. When you are finished, hit q to quit less. Remember how to browse using less; it is a safe way to view a file since it does not alter either the file contents or its time/date stamp.

9. cat  Similar to less, cat is useful for reading files that are less than a screenful in length. To read the README files using cat, type the following command:
   cat README

   Note that you do not have to enter any commands to make cat stop executing. It will simply print the contents of a file to the screen and stop.

3.  Learning the vi Editor

A common way to get information (including programs) into the machine is with an editor. We teach a simple but useful editor called vi (for visual). vim is an enhanced version of the vi editor which is available on most UNIX/Linux boxes. vi has two ways of interacting with you, command mode and insert mode. In command mode, the commands you type do not appear on the screen; they cause various things to happen to the existing characters in the file, or allow you to move around in the file. In insert mode, the characters you type appear on the screen and are inserted into the file. When you enter vi, you are automatically in command mode. Once you get into insert mode, you can return to command mode at any time by pressing the escape (Esc) key (top left of the keyboard). The letters i, I, a, A, and cw are some commands that allow you to enter insert mode.

4.  Practice Exercises to Do Now

vi rhymes

The text file rhymes is now displayed on your screen, and you are in command mode. You may freely modify rhymes since it will not be graded. Note: <Ctrl> f, for example, means to hold down the Ctrl and f keys at the same time. <number> means to type a reasonable positive number. Try all of the following while you have the file rhymes in the vi editor:

1.  Command mode (remember, hit Esc to enter command mode):

1. arrow keys  - Experiment with the arrow keys and learn to move around a file.

2. h, j, k, l  - The same as the arrow keys.

3. arrow key or h, j, k, l  - Move the cursor the number of lines or spaces. Try 4j, 20h, and others.

4. <Ctrl> f  - Forward one screen. Experiment with this to see how it works.

5. <Ctrl> b  - Backward one screen. Same idea as forward.

6. G and gg  - G will take you to the end of the file. Once at the bottom, try the previous two commands and use arrow keys some more. Use gg to go to the top of the file.

7. <number>G  - Go to line <number>. Pick any line number and go there, such as 22G.

8. :<number>  - Go to line <number> as well. Try :20 to go to line 20. Tip: In vi, you do not have to use the Shift key to get the colon.

9. /<pattern>  - Search for pattern. Search for the word pig (/pig). Now type n to find the next instance of pig. Repeat the n until it is clear what is happening. Notice that /pattern is not case sensitive.

10. dd  - Delete the line that the cursor is on at the time. Go to line 18 (:18) and delete it. Go somewhere else in the file and delete another line. Note: The cursor does not have to be at the front of the line in order to delete it using the dd command.

11. <number>dd  - Delete <number> lines. Search for "flappity" and type 7dd to delete seven lines.

12. u  - Undo the last change you made. You just deleted seven lines; now type u. The lines will reappear since you "undid" the last command. Try u again and again; notice what happens.

13. x  - Delete the character that the cursor is on at the time. Type x to try it. Type 6x to delete six characters.

14. dw  - Delete the word that the cursor is on at the time. Search for "semantics" and delete it. Search for "funny" and type 2dw to delete two words. Try u again to restore the words.

15. .  (period)  - Repeat the last command. Go to line 23 and delete it. Try the . command to delete the next line. Now try 4. to repeat it four times. Try u again.

16. $  - Move to the end of the current line.

17. 0 (zero)  - Move to the beginning of the current line.

18. z (Enter)  - Redraw the screen with the current line at the top (hit z, then Enter).

19. Go to the middle of a line and try the three commands w, b, and e. Notice what they do.

2.  Insert mode  - Enter insert mode when you want to add text to the file. Exit with <Esc> (Escape).

1. <Esc>  - Return to command mode from insert mode. If you are already in command mode and hit Esc, no harm is done. Try it now: Bang (gently!) on Esc a few times; nothing is changed. Hit Esc if you aren't sure what mode you're in, or if strange things are happening. Remember this!

2. i  - Insert. This command will enter insert mode before the position of the cursor. Go to line 8 and insert "silly" before "man". You can do this with a search (/man, then hit n until you get to line 8), or use the arrow keys, whichever you like. Make sure the cursor is at the beginning of the word man (on the letter 'm'), then type i silly. Return to command mode with Esc.

3. a  - Append. This command will enter insert mode after the position of the cursor. This is especially valuable if you want to append to the end of a line. Search for "Bo-Peep" and go to the end of the line by typing $. Hit the character a and type any word to append the word to the line. Return to command mode with Esc.

4. A  - Append. This command will enter insert mode at the end of the current line.

5. o  - Open a line below the current line and enter insert mode. Try it now, type something, then return to command mode.

6. O  - Open a line above the current line and enter insert mode.

7. cw  - Change word. Enter insert mode to change a word. Changes the current word from the cursor to the end of the word, replacing the characters with the new characters until you type Esc. Try it now, type a couple of words, then return to command mode. Now try 3cw to change three words.

8. <Backspace>  - While in insert mode, delete characters before the cursor. Go into insert mode and insert some characters. Do not hit Esc. Now hit Backspace one or more times to delete some but not all of the characters you typed in while in insert mode. Now hit Esc.

3.  Saving files, exiting vi

Practice the following four commands and learn the differences to prevent heartache.

1. :w  - Write the file to save the current changes. This command modifies the time/date stamp on the file. It is important to save your changes periodically, especially if you are working remotely (away from the lab) in case there is some hardware failure or power outage. Try this now on file rhymes.
2. :q  - Quit vi if no changes have been made. Make a change to rhymes: Delete a word, insert a character, whatever. Try the :q command. "No write since last change (add ! to override)" will be printed at the bottom of your screen. The :q command executes only if you have not modified the file.
3. :wq  - Write and quit vi. This saves the changes to the file and exits vi. This command also modifies the time/date stamp on the file. Try it now to save your changes and exit the file rhymes.
4. :q!  - Quit vi without saving changes. Be very careful with this command since you will lose all your work for that session if you haven't saved the changes. This command is most commonly used when you enter vi and misspell the file name. It does not modify the time/date stamp.

5.  Handy List of Common vi Commands

Motion:

• move around within text:   use the arrow keys, or h, j, k, l
• move forward one screen:   <Ctrl> f
• move back one screen:   <Ctrl> b
• move to bottom of text:   G
• move to top of text:   gg   or   :1 or   1G
• move to a pattern:   /<pattern>
• move to next instance of the pattern:   n

Inserting text:

• insert before cursor:   i
• insert after cursor:   a
• insert at end of line:   A
• return to command mode:   <Esc>
• delete a character in insert mode:   <Backspace>

Deleting text:

• delete a character:   x
• delete a word:   dw (cursor must be on beginning of word)
• delete a line:   dd
• delete 12 lines:   12dd
• delete 31 words:   31dw

Miscellaneous:

• undo last change:   u
• undo last undo:   <Ctrl> r
• undo all changes to line:   U
• change a word:   cw (followed by the change)
• replace a letter:   r (followed by the new letter)
• save text:   :w (write to file saving changes)
• exit vi (no changes made): :q   (quit, do not save changes)
• save and exit:   :wq
• exit without saving:   :q! (Both dangerous and useful!)
• refresh screen:   <Ctrl> l (the letter l, not the number 1)

Return to this part of the lab and practice the vi commands until you are comfortable with them.

One way to master the editor is to access the online tutorial. On the cs102 web page in the menu on the left, move your cursor over the line labeled "Other Links" (a menu will pop up), and click on "vim tutorial." You can take a peek now, but continue with the lab now while you have TA help. Plan to return to the tutorial before the next lab.

6.  Solving a Problem on the Computer

• Design an algorithm to solve the problem
• Follow your algorithm to write your C++ program and use an editor to enter it into a file
• Trace your C++ code until you are convinced it is correct; modify it as necessary
• Compile the program
• Correct any errors and recompile
• Execute or "run" the program
• Type in any required input
• Examine the output to make sure it is reasonable
• Document (comment) your code

If the program contains syntax or parse errors (errors in the form of the program), error messages will appear on the screen when you attempt to compile it. Read them! Note the line numbers, and remember that the command <number> G takes you to the line in number. (Also, :<number> does the same thing.) Sometimes, the error is actually on the line above. You must correct these errors before you proceed.

Often the compiler will inform you that your code has many errors when in fact it has only one or two. Therefore, first fix any error listed as a parse error, which will most likely be a syntax error. Then recompile your program. Often many (or all) errors will disappear.

7.  Editing and Compiling a Program

1. Move to a window on the right. List your files (ls) and notice the file hello.cpp. The letters cpp following the file name is called an extension and suggests to the computer that the file may be written in C++. Your C++ programs will have the .cpp extension.

2. Move to the left window and type vi hello.cpp to open the file. Read it and use the editor to add your name in the header at the top of the file. The cw command is useful here.

3. Recall that a compiler is a program that translates your source code into code the computer can understand. We are using the g++ compiler (and linker) in CS 102. Move to a different window and try to compile hello.cpp by typing

   	    g++ hello.cpp
       

   A list of error messages will now be displayed on the screen. There is something very wrong with the program, which is what these error messages are all about. In this case, the compiler says that there is a problem with operator <. One < was omitted in the cout statement. Once the error is fixed, the compiler will recognize the program as valid.

4. Move back to the left window, which still displays the contents of the file hello.cpp. Use your editor to correct the error. The corrected line of code should look exactly like this:

                 cout << "Hello, world.\n";
         

5. Again, activate the right window and attempt to compile hello.cpp. Do not panic: If you get the same error this time, it is because you have followed the directions exactly. Think about what happened. You corrected the error but did not save the change. Save the changes and recompile.

6. When your program compiles correctly, the Linux prompt will appear with no error messages displayed. If error messages appear, return to your editing window and repeat the required steps until the program successfully compiles. Ask for assistance if necessary.

7. In your right window, use the ls command to view the contents of your Lab1 directory again. How have the contents of your directory changed?

8. Once your program has compiled with no errors, it will produce the a.out file that contains your program compiled into machine language. This is the file you execute (run). To do so, at the Linux prompt type
   ./a.out

9. Once that your program is correct, exit vi.

8.  More vi Practice

1. Use the dw or x command of vi to delete every word in the second line of file1 (leaving a blank line). Next, insert the word "deep" between "In" and "Hyperspace" on line four. Make no other changes to file1.

2. Use dd to delete the third line of file2. Use dw to delete the word "little" from line one. Use x to delete the apostrophe from "he's". Make no other changes to file2.

3. Use the pattern search command /hydrogen to find "Hydrogen" in file3. Use cw to replace "Hydrogen" with "Helium" by typing cw Helium <Esc>. Make no other changes to file3.

4. File fortunes contains fortunes that have been mangled by deleting the last 8 characters of many of the fortunes. Use as many different vi commands to add words to the ends of the lines (or elsewhere) to make the fortunes make sense (perhaps impossible!). Be creative, and have fun. It makes no difference how you change the file fortunes since it will not be graded. The point is to take some time to become more familiar with vi.

9.  Punch and Run -- To be Graded

  /*****
    Determine the monetary value of an assortment of coins.  
                                                                  
    input:  number of pennies, nickels, dimes, and quarters,  
            in order                                         
                                                                   
    output: the value of the coins in dollars and cents        
  *****/
                                                                 
  #include <iostream>
  using namespace std;

  int main()  
  {
     int pennies, nickels, dimes, quarters, cents;
     double value;        // total amount of money in coins  
  
     cout << "\nEnter number of pennies, nickels, ";
     cout << "dimes, quarters\n";
     cin >> pennies >> nickels >> dimes >> quarters;

     /* Compute the total value in cents. */
     cents = pennies + 5*nickels + 10*dimes + 25*quarters;  // STUDY THIS  
 
     /* Convert to dollars and cents, then display. */
     value = cents / 100 + cents % 100 * 0.01;   
     cout << "The value of your coins is $" << value << ".\n";

     return 0;
  }

After saving your changes using the :w command, move to a different window and compile the program with the command g++ coins.cpp. If error messages appear on the screen, you have typed something incorrectly. Read the error messages to help you locate the error, then make your corrections. Use :w to save your corrections, recompile, and repeat the process until the program compiles correctly (seek assistance if necessary). Once you get the Linux prompt without error messages, run the program with the command ./a.out and type in the requested input. Check the output to convince yourself that the code is correct since it will be graded electronically. Run it several times with different inputs. For fun, try negative input values. Do negative values make sense? What about a value of zero?

Once you are finished, close the file. Return to it later to study the code. You should understand what it does and how it does it.

10.  Write a Temperature Conversion Program

Write a program called temp.cpp which prompts the user for a temperature, and then outputs two lines. The first line assumes that the temperature input is in Fahrenheit, and converts it to Celsius. The second line assumes that the temperature that was input is in Celsius, and converts it to Fahrenheit.

You should assume that the input and output temperatures are doubles, but beware:   9/5 is integer division.

11.  Robot Kit

Your kit should have the following contents:

- 1 Scribbler Robot
- 1 fluke
- 1 flashlight
- 1 bluetooth dongle

12.  Connecting to the Robot

rfcomm connect /dev/rfcommKitNumber

,your robot kit should be number, so (KitNumber) should be replaced with the number on your robot kit. You should be prompted with a pop up in the upper right corner requesting a pass key for pairing with the robot. Click the button that says enter pass key, and type

1234

and hit enter. Your robot should now be paired with the computer you are using, and capable of writing programs to use it. You may be required to pair the robot multiple times through out the semester, so remember this process.

13.  Programming the Robot

cp ~cs102/robot_labs/Lab_Skeletons/Lab1/* ~/cs102/Lab1/

Now you should have a file called Lab1Driver.cpp and a file called makefile. Typing make will compile the Lab1Driver.cpp file for you. All of your labs will have a makefile included, but don't forget how to compile programs using just g++.

1. Now open Lab1Driver.cpp with vi.
2. Add the following line of code to the file:

robot.setName("Nemo");

Where Nemo is replaced by any name of your choosing. The name must be surrounded by quotemarks, e.g., robot->setName(Nemo); would not work. If you wanted to print your robot's name, you could use a line of code like this:

cout << "Hello, my name is " << robot.getName() << "!\n";

3. There are several ways to move your robot around. You'll use others later, but for now try adding some (or all) of the following commands to the file.

1. robot.forward(amount,seconds) - move forward, stopping any rotation, for the specified number of seconds.
ex: robot.forward(1, .5);

2. robot.backward(amount, seconds) - move backwards, stopping any rotation, for the specified number of seconds.

ex: robot.backward(1, .5);

3. robot.turnLeft(amount, seconds) - turn left, stopping any forward movement, for specified number of seconds.

ex: robot.turnLeft(.4, 1);

4. robot.turnRight(amount, seconds) - turn right, stopping any forward movment, for specified number of seconds.

ex: robot.turnRight(.4, 1);

5. robot.stop() - stops all movement.

ex: robot.stop();

Feel free to adjust any of the values to see different behavior. (Note: in each method, amount should be a value between 0 and 1. Seconds should be a positive value.) Later, you'll learn to use the robot's sensors and other functions, but for now, just experiment with basic movement.

14.  Submitting Your Work for Grading

102_submit or 206_submit

and follow the prompts. Careful: Your lab section will be listed in the choices; this may be different from the lab number (this is lab number 1). The first time, you might want to ask one of the TAs for help. For more information, read the man (manual) pages for submit. Type man submit to open the manual page for the submit script in the more (similar to less program. When you are finished viewing the manual page, type q to quit.

15.  Finishing Up

When you are ready to leave the lab, you must log off the system. It is of utmost importance that you log off properly. Otherwise, it will be easy for someone else to use your account, possibly maliciously. To log out properly, you should:

1. Save and exit any files you have been editing (remember the :wq command?). Each window should display the Linux shell prompt (cetus18 for example).

2. To exit your Ubuntu session, move the mouse to the top, right corner of your screen. Left-click the button there and click logoff on the box that pops up.

3. You will know you have logged out completely when you see the cetusxx login: prompt asking for the next user's name. Wait for it, and get TA help if needed.

4. Log in again now using your new password to make sure you remember it correctly. Once the machine automatically launches the window manager, log out again.

5. When you are ready to leave, please clean up the area around your machine and take all papers and belongings with you. Do not turn off the monitor. The screen saver will activate in due time.