CS201
Lab 1 - Introduction to Linux and C

Attendance for the first laboratory is obligatory!

Objectives:

• Meet with your TA in person and  learn about his policies and expectations.
• Get up and running using your account on the Linux operating system on a computer in EPS254.
• Use the a2ps command to get printed copy of source files.
• Use an editor (pico, emacs or vim ).
• Use gcc to compile your program.

Readings:

• Read about Linux and a chosen editor on one of the Some Useful Links section of your course web page.
  • Some commands you may want to read about are: ls, pwd, cp, rm, mv, ps, cat, chmod, mkdir, cd, ps, finger, ssh, ftp, gcc, passwd and man.
  • The emacs family has some nice features for programming, but you can use another text editor if you like. I think pico is quite friendly for the first-time users.    

Deliverables: (DUE BY THE END OF YOUR 2^nd LAB !)

• A hard copy of your answers to a set of Linux Questions (shown below).
• Submittal of your helloworld.c, Makefile and answers files.

Lab Rules

• If there are any readings listed on the lab page, you MUST READ them PRIOR to lab. It is the easiest way to avoid becoming lost about what to do and how to do it.
• The lab assignments are due at the time stated next to the Deliverables. This may vary, so be sure to check this for each lab.
• In all 3 exams, questions will be asked from the related lab assignments. It is strongly recommended that you do all assignments.
• Late assignments will not be accepted so make sure that you are prepared when coming to the lab.
• There is a lot of work to do in CS201. Remember, this is where you build a strong programming foundation, so do not fall behind.
• Sometimes, the labs may be slightly changed by your TA, if something is not working, etc. If you have done your lab before the lab period, make sure that your submission fulfills all the requirements. There is only one want to be 100% sure that you submitted the right thing - show up for your labs and talk to your TA!
• Lab Enrichments
• These are the things that may interests advanced students and cover: C extra, additional lab procedures and C++ related topics.
• No exam questions will be based on enrichment topics.
• No lab grade will be based on these topics.

TO DO (for today's lab)

• EVERYONE SHOULD WORK INDIVIDUALLY ON THIS FIRST LAB.
• Be sure your computer is running Linux. If not, reboot into Linux.
• Log in to your account. Visit System FAQ section of http://www.cs.montana.edu to know how to use the linux side of the lab machines.
• Create a directory called cs201 if you have not already done so and go to that directory.
• Create a sub-directory called lab1 inside cs201 to use for today's lab and change to that directory.
• Start up the editor of your choice by typing
  • $ pico  (for the pico editor)
  • $ emacs  (for the emacs editor)
  • $ vim (for the vim editor)

  Here $ represents command prompt.

• Answer the following questions as briefly as possible by typing the answers into the editor of your choice.
1. What does the shell prompt look like on your account?
2. Type ls. What did happen and why?
3. Explain how you made a directory called cs201.
4. Explain how you made cs201 your current working directory.
5. Which commnad will allow you to see the full path to the directory in which you presently are?
6. From your cs201 directory, describe three separate ways to go back to your home directory.
7. Create a directory called test. Create a sub-directory called test1 inside test. Which command will allow you to delete both directories at once?
8. Navigate our Linux system enough to estimate the number of students currently "logged in" on esus. Write down the number and how you determined it.
9. Which command will allow you to know more about a specific linux command such as cp?
• Save this file with the name answers.txt in ~/cs201/lab1.
• Now, build a program in C to print out the phrase "Hello World!" in the screen. Use the text editor of your choice to build the following helloworld.c program. Once you have written your program in a text editor, save it as helloworld.c in ~/cs201/lab1.

/* helloworld.c

* CS 201 - by(your name here) on (current date here)

*/

# include <stdio.h>

int main(void)

{

printf("Hello World!\n");

exit(0);

}

• Create a simple Makefile for your program as follows and save it as Makefile in ~/cs201/lab1.

  # Makefile for helloworld

  # CS201 - by(your name here) on (current date here)
  

  helloworld: helloworld.o

  gcc -o helloworld helloworld.o

  helloworld.o:helloworld.c

gcc -c helloworld.c

1. Compile the program by typing make helloworld at the command prompt.
2. If errors were reported, fix the program and re-make it until it compiles without errors.
3. Execute the compiled program (by typing ./helloworld) and make sure that you see the output in the screen.
• Open your answers.txt file with your text editor and add the answer of the following question.
  1. What is the difference between gcc -c and gcc-o?
• Make sure that your answers.txt file looks okay. Now print hard copy of your source file (i.e. helloworld.c), your Makefile, and your answers.txt file by typing: a2ps -P orca helloworld.c Makefile answers.txt
• Hand in your hard copy to the TA. Be sure to identify each page with your name and staple multiple pages together.
• Submit your assignment as suggested by your TA at the beginning of the class.

LAB 1 ENRICHMENT

• Try changing the helloworld program so it says “Happy New Year!” instead of “Hello World!”.
• Try printing a line of astericks *************** before and after the “Happy New Year” message.
• If you wanted to use the C++ compiler instead, replace gcc with g++.