Goals

To practice using UNIX commands rather than the mouse.

Why



1. You need to work at home on our computers using SSH.
2. You can type faster than you can mouse.
3. Computer scientists master the low level control of machines.
4. Some of the power commands impress your friends, colleagues and bosses.



Process

We abandon using the KDE Graphic User Interface and use only a browser and a terminal window. Inside the terminal window you will practice commands like cd (change directory), mkdir(make directory), and the editor vi/vim.

By the way -- vim is an improved version of vi -- the visual editor. In particular it colors C++ programs in a helpful way.

Rule 0 -- READ ALL THE INSTRUCTIONS ON THIS PAGE before starting lab 3

Rule 1 -- terminate every UNIX command

Commands are not executed until you tap the ENTER key.

Set up

Login. Open this page in a browser. Make this window take up about 50% of your screen.

Open up a terminal window ("f" -> System -> Terminal).

From now on.... type everything in the terminal window that pops up!

This window is working in your HOME directory, by the way. To find out where you are use

 		pwd

(print working directory). Try it now. End each UNIX command by tapping the Enter key.

The following command will configure vi/vim into a more friendly mode than the default:

 		~dick/bin/Q novice

This sets up vi/vim to show numbers and modes on the screen. Q is a program I wrote to help students and faculty do exercises, examples, experiments, and simple projects. This set up is permanent until such time as you edit a file called ".exrc" (don't ask). Meanwhile it makes it easy to compile and run simple programs with out leaving "vi".

Change directory to cs201 by typing a Change Directory command:

 		cd cs201

This moves the window to work on your cs201 directory. Your command line prompt should change.

Make a new directory lab03 by using the Make Directory command:

 		mkdir lab03

Change directory to lab03:

 		cd lab03

Perform all the exercises in this lab inside this directory.

Creating a file using the vi editor

We will now type in and save a small C++ program in a file called "small.cpp".

Type in this command in the terminal window:

 		vim small.cpp

and it creates an empty file called small.cpp.

Rule 2 -- In vi each command is a character

To input text you must tap the "i" key.

Tap the "i" key for input(don't tap Enter!). Input the following code quickly and don't worry about typing errors!

 	main(){}

(This is the smallest C++ program that compiles and runs. It does nothing of course)

When you have typed in the whole program tap the "Enter" key a few times to give a blank line at the bottom.

Then tap the "Esc" key at the top left of the key board.

When you tap Esc vi/vim shifts back to Command mode so that you can save your work and correct any errors you've made.

Now save your work: Enter the following command into vim:

 		:w

and tap the "Enter" Key.

Look at what you typed. Do you see any obvious errors? You can use the arrow keys to move to the error and change it with the following

Key	Effect	Why
x	Delete character under cursor	Typists used to 'x' out errors.
X	Delete character before cursor
r	Replace the character under the cursor
i	Insert string of characters until you tap the "Esc" character.
dd	Delete the current line
dw	Delete the rest of the word.
u	UNDO!

If you now tap the letter "q" (lower case) my "Q" program will compile your program, report any errors, and then run it for you....

Are any compile errors output? If none go to the next experiment.

If you have errors fix it!

More on vi and vim

Look at this page [ ../vi.txt ] which gives a fast introduction to vi and [ ../vi1.gif ] and [ ../vi2.gif ] that show you what each key does. You might like to print these or download them so you can read them later.

Another Quick Exercise

Use vim to create a file discount.cpp from page 42 in the text book. Open the text at the right page and get started with

 		vim discount.cpp

an then tapping i.

Type the program in from the text and tap the Esc key when done.

Save the program (:w) and check for errors. Then fix them.

Save and quit out of vim (:wq).

This time we won't use Q. Use

 		g++ -o discount discount.cpp

to compile and

 		./discount

to test it ... try both costs above and below the bound.

Yet More Vi and Vim

Have a look at [ ../vi.notes.html ] my notes on vi -- complete with alphabetical lists of commands. The CSCI201 search engine on this page will find commands for you. You would be wise to book mark (add to favorites) this page so you can refer to it when you need to find a command to delete a line or open a new line of text.

Copying and Editting a file

We will now change small.cpp into small2.cpp.

Start by using the UNIX cp copy command in your terminal window (if needed first quit vi).

 		cp small.cpp small2.cpp

This creates a copy of small.cpp called small2.cpp.

You can now use

 		vim small2.cpp

to change it to output something when it runs -- anything you like....

Again my 'Q' is a quick way to save, compile, and run a C++ program. Inside vim, ESCape from INPUT mode if needed and tap the 'q' key.

(Hint. you may have to add a couple of extra lines before the main program starts....)

Earn Credit

To earn credit either show the lab instructor the three programs or print them and hand the printouts in.

Notes

Printing from the terminal window

This command seems to work

 		lpr program.cpp

but has been known to print in a different laboratory and to remove the left hand side of your file!

You can produce some very nice looking print outs of code by first passing your file through the "ASCII to PostScript" program like this:

 		a2ps program.cpp | lpr

Other ways to compile a program outside vi

You can quit "vi"/vim

 		:wq

and input the following command

                c++ -o small small.cpp

Or you can try

 		Q small.cpp

and use my 'Q' program.

Rerunning a program inside vi

You can then do another test without recompiling by typing this command into 'vi'

 		:!./small2

(: means here is a one line command, the ! means that you want to run a program outside vi, and ./area3 selects the program to execute from this (.) directory).

Going to a line number in a file inside vi

You can move rapidly to line 42 for example by tapping these keys as a vi command: 42G. The "G" is for "Goto". You can also make many arrow movements by typing the number before the arrow key.

Go directly to line 42...

Suppose there was an error was on line 42 then the UNIX command:

                vi +42 small.cpp

takes you to line 42.

Repeating previous commands

In UNIX you can repeat the c++ command by inputting this command:

 			!c++

Similarly you can repeat your last "vi" or vim UNIX command

 			!vi

You can use the arrow keys to repeat previous commands.

In 'vi' the dot key '.' repeats the previous command, and n repeats the previous search, so you may hear someone doing this:

 		n.n.n.n.n.n.n.

to find and replace an identifier!

A Quick list of UNIX Commands

There are many commands in Linux/UNIX. Here is a list of some of them:

Command	Purpose
cat >f	Upload or input a file called f. End with Enter and Control/D
cat f	View file f.
lynx u	View a web page with URL u.
g++ -o p p.cpp	Compile a program called p.
./p	Execute/run a program called p in this directory(.)
make t	Follow a recipe in Makefile to make t
cd d	Change working directory(folder) to d
pwd	Print working directory
ls	List the the names of files and directories in this directory
mkdir d	Make a directory called d
more f	Display a file f one screen at a time, Tap space for a new screen
rm f	Remove a file (dangerous....)
mv f n	Change f's name to n, or move it to a directory
cp f n	Copy f to a file named n
vi f	Edit a file called f (powerful but not easy to use)

UNIX for Beginners

umenu	A Simple menu driven shell written by CSUSB students for CSUSB students to use.
pine	Handle your EMail.
pico f	Edit a file called f (easy to use but not powerful).

See Also

Frequently asked questions about CSCI.CSUSB.EDU [ ../../doc/CS_FAQ.html ]

. . . . . . . . . ( end of section Notes) <<Contents | End>>

. . . . . . . . . ( end of section CSCI201 Laboratory 4 -- More powerful tools) <<Contents | End>>

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