CPS 100E, Fall 1995 Lab 1

This is only a brief introduction to many tools. You'll need to spend some time on your own experimenting further. You should buy the Introduction to the Public Unix Clusters at Duke from the Gothic Bookstore for more information.

In this document, commands that you type will be in a font that look like this , sometimes such commands will be quoted --- ``like this!'' --- do NOT type the quotes, just type what is between them. When instructed to type something, press the return key after typing it.

Logging in

SUN Workstations should already be turned on. If the screen is blank, try moving the mouse to make the screen reappear. You should already have a user id and a password. At the login prompt, type your login id and press the Return key. Type your password and press the Return key. Your password is not displayed on the screen, so that anyone looking at your screen will not see your password.

Now wait until two windows labeled xterm appear. There will also be several other items appearing on your screen.

Managing Windows in X

               xlogo &

The gray fuzz covering most of the screen is called the {\it background}. Move the mouse to any area of the background and try clicking the three mouse buttons each at a different time. Each button brings up a different menu of applications. We'll select a few of these during this lab, and you can try the rest on your own later.

Most windows have title bars across the top of the window. Move the mouse to the title bar for the Xlogo window. Click and hold the left mouse button. Move the mouse and the window should follow. You can also move windows using the Window Ops commands that appear when you click and hold the left mouse button when the mouse points at the background.

Another useful window command is resizing the window. This command can be found in the Window Ops menu. A faster way is to move the mouse cursor to the title bar and click and hold the right mouse button. Try this with the Xlogo window. An outline of the window appears. Move the mouse outside of the window boundary and you will see the outline grow (and shrink if you move in the other direction). When you release the mouse button, the Xlogo window is a different size than before.

To get rid of windows you no longer want, click once on the kill icon along the top of the screen. The cursor becomes a skull and cross bones. Move the mouse to any position inside the Xlogo window and click. The window should disappear.

Useful UNIX commands

    [1] rodger@teer8%

To make the font bigger you can hold the control key down while pressing and holding the right mouse button. Choose medium or large for an easier-to-read window.

• Skip this step if you don't want to alter your .cshrc, .login, .emacs, or .Xdefaults files.} (You can always go ``back'' to the old version of each.) If you don't run ~ola/setup you must still change your path so it includes ~ola/bin in order to run the submission program used to submit assignments.

  From within an xterm window at the prompt type ~ola/setup . This will set up some files in your directory to make life easier for use in the programming classes at Duke.

• To change your password, type passwd

  If this is a new account, you should change your password to something that is easy to remember, but not easy for someone to guess. Do not use your name, or an English word, but rather compose a password formed with letters numbers, upper and lower case letters, and punctuation marks.

  LOGOUT AND LOG BACK IN. In order for the setup command to make the changes, you need to logout and then log back in. To logout of your SUN workstation, click the logout icon at the top left of the window.

  Once logged back in, move the mouse to one of the xterm windows.

  You might notice that the text inside the xterm window is tiny. To change the font size (make the test larger) press and hold the control key (the key to the left of the A key), and press and hold the right mouse button. A menu appears, and you can select Large or another size.

• To create a directory called cps100e for storing new files related to this course, type {\tt mkdir cps100e} DO THIS NOW.
• Create another directory called public by typing mkdir public
• Files can be stored in either directory and are accessible by other users on the system. To make your cps100e directory inaccessible by others you must restrict permissions by typing

      fs setacl cps100e system:anyuser none
  

• (optional, BUT advisable) You can allow certain individuals access to a specific directory so they can look at your files, but are not allowed to modify any of your files. If you'd like Prof. Rodger and Prof. Astrachan to be able to look at your files when you have questions, then you can give them permission to look at all files in your cps100e directory by typing the following two commands (they won't look at your files unless you ask them to):

     fs setacl cps100e rodger rl
  
     fs setacl cps100e ola rl
  

• To list your files and directories, type ls

  You should see both the directories you created and possibly some additional files.

• When you login, your session begins in your main directory. To see the name of your directory, type pwd

  The complete name should look similar to /afs/acpub.duke.edu/users15/rodger except the number may be different, and your login id should be the rightmost word.

• Commands useful for navigating in directories are listed below:
  • cd (change directory)
  • popd (pop directory)
  • dirs (show directory stack)

  For example you can type cd ~ola to change into Owen Astrachan's directory. Type ls to see files and directories.

  Type ``cd'' (press return) then type ``pwd'' (print working directory) to see where you are. You should be in your {\em home} directory.

  Type ``pushd ~ola'' and press return, then type ``pwd''. Then type ``dirs'' to see the directories in your directory stack. Now type ``pushd ~pott'', then ``ls'', then ``dirs''. Then type ``pushd'' followed by {\tt pwd}. Finally, type ``popd'' repeatedly until you're told that the directory stack is empty.

• Files for classwork should be kept private. To create the programming assignment for lab 1, you should change to your cps100e directory by typing ``cd cps100e'' (from your main directory).

  Now when you type ``ls'' you will see there are no files in the cps100e directory, because you haven't created any yet. To see that you are in your cps100e directory, type ``pwd'' and the complete directory name (or path) should be as before, but with ``/cps100e'' added to the right. Create a directory lab1 using the mkdir command by typing

         mkdir lab1
  

  then change into this directory with ``cd lab1''.

Assignment 1: A word is like no other

You'll edit, compile, and run a program in this lab. Instructions for editing, compiling, and printing will be given below.

You'll need to copy some files to your lab1 directory first by typing (don't forget the ``.''):

      cp ~ola/cps100e/lab1/*   .

You'll also need to create a link to a directory containing large data files (instead of copying them). Type:

       ln  -s  ~ola/data  data 

If you now type ``ls'', you will see that you have a new directory calleddata.

Now complete the C++ program words.cc using the emacs editor (described below).

You should fill in your name, date, and a description of the purpose of the program, and then complete the Store function. Compile, run, and print a copy of the program. Instructions for editing and compiling will be given below.

#include 
#include 
#include "vector.h"
#include "CPstring.h"

// Name: 
//
// Date: 
//
// Purpose: 

void Store(Vector & wordList,
           int & wordCount,
           const string & word);

void Print(const Vector & wordList, int wordCount);        
           
main()
{
    string filename;
    ifstream input;
    string word;

    Vector wordList(10000);         // make room for lots of words
    int wordCount = 0;                      // how many words there are
    
    cout << "filename ";
    cin >> filename;
    input.open(filename);

    if (! input.good())
    {
        cout << "couldn't open file " << filename << endl;
        exit(1);
    }


    while (input >> word)                    // one word at a time
    {
        Store(wordList,wordCount,word.Downcase());
    }

    Print(wordList,wordCount);               // print list of words
}

void Store(Vector & wordList,
           int & wordCount,
           const string & word)
     
// precondition: wordCount = # words in wordList
// postcondition: if word is NOT in wordList, it is added at the
//                end and wordCount is incremented to reflect addition
{
    // needs to be implemented    
}

void Print(const Vector & wordList, int wordCount)
{
    int k;
    for(k=0; k < wordCount; k++)
    {
        cout << wordList[k] << endl;
    }
    cout << "total of " << wordCount << " unique words" << endl;
}

Note that on the second line that starts with ``cout'', there is a space between Engineers and the double quote. Creating your program using the editor emacs To type in your program you need to use an editor. To use the editor emacs to modify the file words.cc, type ``emacs &''.

An emacs window should appear. In emacs the commands are written in the form C-x or M-x . The notation C-x is the same as CTRL-x, and means to press and hold down the control key (the key to the left of the A key) and press the x key, and then release both keys. The notation M-x is the same as ESC-x, and means to press the ESC key and release it, and then press and release the x key.

If the print in your emacs window is not large enough, you can make it larger. (This will only work if you previously typed the setup command). Type the emacs command M-x big by first pressing and releasing the ESC key, and then typing ``xbig'' and pressing the return key. (look in the minibuffer window at the bottom of the screen to see if it's working as you type).

To edit a file from within emacs, type ``C-x C-f'', (that's control-x control-f). When the prompt for {Find file:} appears in the small mini-buffer window at the bottom of the emacs window, type ``words.cc'' and press return. Be sure to specify the full path, you might need to type ``~/cps100e/lab1/words.cc'' in the mini-buffer. You can edit within the mini-buffer using standard emacs commands.

If you look carefully at the emacs information (black) bar, it should be C++ fill or something similar.

You should then enter the program shown above. Be careful that you type it just as it appears. You'll notice that when you type a left-brace { the right brace appears ``automagically'' with the cursor positioned and indented properly.

If you make a mistake, use the following emacs commands to move around and edit in the window. If you begin an emacs command that you do not want to complete, type ``C-g'' (press and hold the Control key and then press g) to cancel the command.

Alternatively, you can also click on Edit and File at the top of the emacs window to do some of these commands.

To save the buffer (the region in emacs in which you're typing) use ``C-x C-s'' (a message that the buffer has been written should appear in the mini-buffer). When you're reasonably sure that the program is correct you're ready to compile it.

In general, you should always have an emacs window open. Unless you are logging off, there is seldom a reason to quit emacs. You can, however iconify (make small) the window by clicking the mouse on the dot-button in the upper-right of the window. This works for any window. Double-clicking on an icon opens that application.

When you believe the C++ program is correct, save the file by typing a sequence of two emacs commands: C-x C-s

The file will stay there, but you should see a note at the bottom of the emacs window indicating the file has been written to memory. Compiling a C++ program A compiler transforms your C++ code into machine readable code the computer can understand. Programs can be compiled from within emacs or from the shell (in an xterm window). Compiling from within emacs will save LOTS of time in the long run. To compile from within emacs type ``C-x c''. Do not type ``C-x C-c'', cntrl-x cntrl-c, this quits emacs . If ``C-x c'' doesn't cause a prompt to appear in the mini-buffer, you should type ``M-x compile''. The default compile command of make -k appears in the mini-buffer. You should compile by editing the command so that it reads ``make words'', then hit return. It will take a while for the program to compile, but you should see an emacs sub-window with an indication that something is happening.

If there is a syntax error in the program, a message will appear in the *compilation* buffer. To goto the error you can type C-x ` --- that's control-x followed by a back-quote (look in the upper left corner of the keyboard). This command will always goto the next error, so you can use it to cycle through multiple errors, fix them, and then recompile. If there are multiple error messages, fix the first one only and then recompile. Sometimes one error causes the compiler to list additional errors that are not really errors.

An example of an error message is:

           words.cc:8: syntax error before '<'

This message tells you the name of the file (words.cc), the line number the error occured near (line 8) and a guess as to what is wrong. You don't need to worry about where line 8 is, typing C-x ` moves to this line.

When the program has been successfully compiled continue with the next section.

If you don't have any errors with the first compile, you might want to modify the program so that there is an error so you can see what happens when you compile a program with an error. Once there are no errors, move on to the next section.

Execute your program

From an xterm window, list the files in your lab1 directory. You should see both words.cc and words. The file words is an executable program. The compiler translated your C++ program into machine code the SUN can understand and stored this code in the executable file words.

To run any executable program, type its name, so type ``words'' to execute this program. This program will ask you to type in the name of a data file, to see the number of unique words in hamlet, type: ``data/hamlet.txt'' for the name of the file.

Type ``ls -lt'' to see how big your files are and when they were created. At the end of the lab be sure to type ``rm words'' to remove the executable (which is really big). You can always re-create it by recompiling the source code.

Print a copy of your program

The print command sends your file to the printer in the room you are currently in. If several people try to print at the same time on the same printer, the print jobs are queued and printed one at a time. To see where in the queue your job is type ``lpq'' followed by -Pname where name name is replaced by the printer name. In Teer 106, the printers are in the back of the room.

If you want to specify a specific printer, use the lpr command. There are two printers in Teer 106, named teerlp1 (the last three symbols are lowercase L, p, and the number 1) and teerlp2. To print any text file use the lpr command, specify the printername (prefixing it with -P , specify the file is a text file by -Fl (with lowercase L here) and type the file name. To print your program words.cc on the printer teerlp1, type

     lpr -Pteerlp1 -Fl words.cc

Give your program to the TA and make sure your name is checked off for your participation in the lab. You are not done yet!.

Surfing the Internet

If you have never used Netscape before, you will need to click on ``accept'', and then the Netscape window will appear. Click once anywhere in this window and the Duke homepage will appear. From here, you can click on any highlighted text to get more information on the item. Click on back to retrace your steps. To answer the following questions, you'll need to find the CPS 100E homepage, and Prof. Astrachan and Prof. Rodger's homepages.

Write the answers to the following questions in a file called ``answers''

• Whose pictures appear on the CPS 100E homepage?
• How many graders are there for CPS 100E?
• What is the name of Prof. Astrachan's automated theorem prover?
• What type of critter is Fritz (one of Prof. Rodger's pets)?

Submitting Assignments

    submit100e lab1secN file1.cc file2.cc ... README 

where the first argument to the program (after {\tt submit100e}) is the assignment name. If you type an invalid assignment name a message will appear. After the assignment name comes all the files you need to submit as part of the assignment. The file names that are arguments to the submit program can be entered in any order. Every assignment must have a README file submitted with it (please use all capital letters). Include your name, the date, and an estimate of how long you worked on the assignment in the README file. You must also include a list of names of all those people with whom you collaborated on the assignment. So for this assignment, create a README file by using emacs, and ``C-x C-f'' to find a file named README. Then try to submit electronically by typing (where N below is replaced by your section number: 1, 2, 3, 4, or 5)

    submit100e lab1secN words.cc answers README

Leaving

If you have not saved all your files, you will be asked at the bottom of the window whether or not to save a particular file. Type y or n for each file. When you are asked ``Subprocesses are executing; kill them and exit?'' type yes and press Return. At this point, the emacs window will disappear. Always exit emacs before logging out!

To logout of your SUN workstation, click on the logout icon at the top left of the screen.

You will see all the windows and icons disappear and you will be logged off. Never turn off the workstation!

Remember this is only a brief summary of useful commands to get you started. You'll need to refer to the other documents mentioned on the first page to learn more.