Introduction to Unix, C++ programming, Emacs, and Netscape

• Understand how to login to and logout from the Sun Workstations found on campus

• Become familiar with basic Unix tools including:
  • Copying, moving, deleting files
  • Traversing and moving between directories
  • Invoking programs including editors and compilers

• Know how to change your environment so that you have access to programming tools and so that your editor (xemacs) is configured to give you help when you edit C++ programs

• Know how to use netscape to access web pages including the page for the course

• Know how to edit, compile, debug, and run a C++ program

Table of contents

This is only a brief introduction to many tools. You'll need to spend some time on your own experimenting further. You should consult the duke.cs.cps006 newsgroup and the OIT online help page for more information. A summary of Unix commands (in postscript) is available.

In this document, commands that you type will be in a font that look like this , sometimes commands may 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

• Workstations are always on, do NOT turn them off. Wiggle the mouse if the screen is off.

• Type your userid, hit return, type your password (your password isn't displayed). Note: passwords are case-sensitive, Apple is different from apple.

• Wait until two windows labeled xterm appear, this may take a while.

  Sometimes a message of the day window (MOTD) pops up (this window is labeled with xmessage at the top) with important information. If this window has appeared, then you can click the left mouse button on the bar that says "click here with the Left Mouse Button to continue" and this window will disappear. When this message does appear, you should read it as it usually contains important announcements.

• You may find it easier to read this document using netscape, a web browser. The browser lets you hop easily between sections of the document using hypertext links. To use Netscape.
  1. Click on Netscape in the menu bar to launch the browser.
  2. Click on the File button at the top of the Netscape window.
  3. Click on the Open Page that becomes visible as a result.
  4. Enter the address of the CPS 6 web page

     www.cs.duke.edu/~dr/cps6.html  

     and press return.

  5. Find the Lab 1 document under Labs and click on it.

Managing Windows in X

The two rectangles labeled xterm are called windows. The row of small rectangles containing pictures in the top left position of the screen is a menubar which contains some icons. Icons represent windows that are temporarily hidden. Click the mouse (left button) on the picture of the calculator (also labeled xcalc) and wait until a calculator appears on the screen.

• The green with black dots covering most of the screen is called the 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. Don't try any of these now, you can try them on your own later.

• Most windows have title bars across the top of the window. Move the mouse to the title bar for the Calculator window. Click and hold the left mouse button on the word Calculator. Move the mouse and the window should follow. Let go and the window will be in its new position. (Note: 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 to the background.)

• Another useful window command is resizing the window. Move the mouse cursor to the Calculator title bar and click and hold the right mouse button. 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 Calculator window is a different size than before. (Note: This command can also be found in the Window Ops menu.)

• 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 Calculator window and click. The window should disappear.

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Useful UNIX commands

An operating system is a large program that coordinates all the resources for the execution of programs. Unix is the operating system on the SPARCstations. You'll need to learn lots of commands, a few important ones are introduced here. To enter a command, type after the prompt in one of the xterm windows. You should see a prompt that may look similar to

    [1] dr@teer8%

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

Before executing commands, you need to reconfigure your environment. This is explained below. You'll then logout, log back in, and write a C++ program.

Skip the reconfigure step if you don't want to alter your .cshrc, or .login files. (You can always change back to your old version of these files.) However, if you don't run the set-up program ~dr/cps6/setup   you must still change your path so it includes ~dr/bin   in order to run the submission program used to submit assignments. You must also include /afs/acpub/project/cps/bin in your path to have access to the g++ compiler. If you don't run the setup script you must change your path, it's most likely set in your .cshrc file.

Reconfiguring

• From within an xterm window at the prompt type ~dr/cps6/setup  . This runs a program that will set up some files in your directory to make life easier for use in the programming classes at Duke. If you don't get a prompt back after typing the command, consult a TA. Your old dot files, e.g., .cshrc are saved with a .old extension, e.g., .cshrc.old

• 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.

  To change your password, type passwd

• Logout, then 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.

Creating and Traversing Directories

• To create a directory called cps6 for storing new files related to this course, type

  mkdir cps6

• You may decide to keep other users out of your new directory (so that they can't look at your files) by protecting your directory. This is a preferable, but your decision. To do this type the command below.

      fs setacl cps6 system:anyuser none
  

• If you protected your directory with the command above, you need to give the professors and TAs access to your code if you ever want to ask questions about what you're doing. You can give access to just professors and TAs by typing the command below (no one will look at your files unless you ask them to).

     fs setacl cps6 dr:cps6 read
  

• To list your files and directories, type ls (think of this as "list"). You should see both the directories you created and possibly some additional files. Type ls -a to see dot files too (e.g, .cshrc).

• To see permissions on a directory, type

  fs listacl cps6

  (substitute any directory for cps6).

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

  The complete name should look similar to /afs/acpub.duke.edu/users/d/r/dr . Your login id should be the rightmost word.

• The command to change directories is cd. For example you can type cd ~dr   to change into Dr. Ramm's directory. Type ls to see files and directories.

• Type cd (press return) then type pwd to see where you are. You should be in your home directory. Type cd cps6

  Now when you type ls you will see there are no files in the cps6 directory, because you haven't created any yet. To see that you are in your cps6 directory, type pwd and the complete directory name (or path) will tell you where you are.

• Create a subdirectory lab1 using the mkdir command by typing

         mkdir lab1
  

  then change into this directory with cd lab1

You are now ready to begin typing and compiling a C++ program. The section below on Edit, Compile and Debug tells you how to do this.

Summary of Unix Commands

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Programs: Edit, Compile, Debug

Instructions for editing, compiling, and printing are given below. First you'll need to copy a Makefile to your lab1 directory. The copy command is cp so from within your lab1 directory type (don't forget the dot: "."):

Type ls to see that the file was copied. You should see a file called Makefile. We'll use the Makefile to compile programs in this course. This Makefile will automatically link to libraries that will be used in this course, including those used in CPS 6. You can use it for other C++ programs you write as long as the complete program is in one file. If you write a program in multiple files, you'll need to modify the Makefile.

A C++ Program (4 pts)

Creating your program using the editor xmacs

To type in your program you need to use an editor. To use the editor xemacs to create a file use the menubar if there is an xemacs icon or type in an xterm window:

       xemacs &

(Note: Typing the "&" after the word xemacs will allow you to continue to type commands in your xterm window.)

An xemacs window should appear (please be patient!). You can use the arrow keys and the mouse to move around in the xemacs window. You may be able to just type in the program without looking at descriptions of different xemacs commands below, but you'll need to know these commands at some point during the semester.

Many xemacs 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 at the same time, 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 (The M is for meta, don't worry about this).

Note that for control characters you must hold down the control key and the other key at the same time, whereas for escape keys you press escape, let go, then press the other key!

Make sure you see the complete xemacs window on the screen. If you can't see the bottom of the window, then move the window until you can see the whole thing.

Loading, Editing, Saving Files

• Use the file menu to load a file (even one that doesn't exist yet). Click and hold the menu and choose Open before releasing the mouse button.

• The prompt for Find file: appears in the small mini-buffer window at the bottom of the xemacs window. You should also see a path which might be ~/   or ~/cps6/lab1/   . If you don't see this, then you may not be in the correct directory, so consult with a TA. You can edit what appears in the mini-buffer with arrow/delete keys.

• You will create a file named feyneman.cc, so complete the path in the minibuffer so that it reads ~/cps6/lab1/feyneman.cc  and press return. (Note: Instead of using the menu to open the file, you can open the file by typing C-x C-f, (that's control-x control-f)).

• Enter the C++ program shown below. Be careful that you type it just as it appears. You'll notice sometimes after you type something, the cursor will "automagically" move to another position to indent properly. When you type a "}", the cursor always jumps back to the "{" for a second so you can see if the "}" matches with the correct "{".

  Using the editing commands described you are to type in the program shown, be sure to use your name and the current date .

  #include <iostream.h> // Author: YOUR NAME HERE // Date: TODAY'S DATE // Course: CPS 6 // Section No: YOUR SECTION NUMBER HERE (01) // Purpose: Practice C++ int main() { cout << "Nature uses only the longest threads" << endl; cout << "to weave her pattern, so each small piece" << endl; cout << "of the fabric reveals the organization" << endl; cout << "of the entire tapestry" << endl << endl; cout << " Richard Feyneman" << endl; return 0; }

• If you make a mistake, use the following xemacs commands to move around and edit in the window. If you begin an xemacs 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 xemacs window to do some of these commands. You can use the mouse to position the cursor within xemacs and you can use the arrow-keys and the scroll-bar to move around too.

In general, you should always have an xemacs window open. Unless you are logging off, there is seldom a reason to quit xemacs. 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.

Until you save your file, it is stored in a buffer (the region in xemacs in which you're typing). When you believe the C++ program is correct, save it by clicking the File button at the top of the xemacs window, and then selecting Save Buffer. A message that the buffer has been written should appear in the mini-buffer. (Alternatively, you can use the command C-x C-s).

Compiling a C++ program

A compiler transforms your C++ code into machine readable code the computer can understand. Programs can be compiled from within xemacs or from the shell (in an xterm window). Compiling from within xemacs will save LOTS of time in the long run.

• To compile from within xemacs type C-x c. Do not type C-x C-c (cntrl-x cntrl-c) this quits xemacs.

  If C-x c doesn't cause the prompt Compile command: make -k to appear in the mini-buffer at the bottom of the screen, you should type M-x compile (press escape, let go, press x, then type the word compile.)

• The command make -k, which appears in the mini-buffer, is the default command. You should compile by editing this command (use the back space key to delete the -k) so that it reads make feyneman, then hit return. It will take a while for the program to compile, but you should see an xemacs 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 get to the error you can type C-x ` that's control-x followed by a back-quote (look in the upper right 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:

  feyneman.cc:5: unterminated string or character constant feyneman.cc:5: possible real start of unterminated constant

  This message tells you the name of the file (feyneman.cc), the line number the error occurred near (line 5) and a guess as to what is wrong. You don't need to worry about where line 5 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. For example, remove a ";" and then compile the program. Once there are no errors, move on to the next section.

Execute your program

• In an xterm window, type ls to see the files in your lab1 directory (ask for help if you get lost).

  You should see both feyneman.cc and feyneman. The file feyneman is an executable program. You might also see a file called feyneman.cc~  . This is a backup copy of your program that xemacs automatically creates. It is not an exact copy, but rather a copy before you made your most recent changes.

• To run any executable program, type its name, so type feyneman to execute this program. Type ls -lt to see how big the files are and when they were created. When you are finished with this document, be sure to type rm feyneman to remove the executable (which is really big). You can always re-create it by recompiling the source code.

Show A Lab UTA (1 pt)

1. Show the files in your lab 1 directory.
2. Show the path name for your lab 1 directory.
3. Run the program feyneman.

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 at the front 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

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Surfing the Internet (3 pts)

If you have never used Netscape before, you may 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. From the Duke homepage you should be able to find your CPS 6 homepage or Dr. Ramm's homepage.

You can find the home pages by either navigating from the Duke page (to departments, people, or faculty) or by using the Open option at the top of the netscape title bar and entering the URL for the class web pages:

You can leave off the http:// or for Dr. Ramm's course you can type just www.cs.duke.edu/~dr/cps6.html   and then click on the link to the CPS6 web page.

Write answers to the following questions in a file called answers. You should create this file using xemacs. You'll need to submit the file at the end of the lab.

• How many tests from previous semesters are currently listed on the CPS 6 web page?
• What is the name of Prof. Ramm's daughter?
• What kind of dog does she own?
• What and where is she studying?

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Submitting Assignments

    submit6 lab1 file1.cc file2.cc ... README 

where the first argument to the program (after submit6) 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. You can enter the files 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 or lab. So for this lab, create a file named README using xemacs. Then submit electronically by typing

    submit6 lab1 feyneman.cc answers README