[SOLVED] Csci493.66 assignment 1 p0

Preface
This assignment is a warm–up programming exercise. The program that you need to write is small, but you’ll have to learn a few things to write and run it.
Instructions
For this first assignment you’ll write a short C program. This program will have just two lines of output. The first line will contain the username of the user who runs it, along with their userid and home directory, all in a single sentence of the following form.
My username is sweiss, my userid is 1220, and my home directory is /data/biocs/b/cshome/sweiss.
in which sweiss is replaced by the person’s username, 1220 would be replaced by their userid, and /data/biocs/b/cshome/sweiss would be replaced by the absolute pathname of their home directory. The output must be exactly in this form, absolutely, without exceptions! The second line of output will be one of the following two lines:
My shell is path-to-shell in which path-to-shell is replaced by the actual value of the SHELL environment variable or
The value of my DISPLAY variable is display-variable-value in which display-variable-value is replaced by the actual value of the DISPLAY environment variable.
Which line is your program supposed to output?
• If your actual userid on our computer network is an even number, your program must output the SHELL variable line.
• If it is an odd number, your program must output the DISPLAY variable line.
If I ran this program on the server, the session would look like the following:
$ hwk1
My username is sweiss, my userid is 1220, and my home directory is /data/biocs/b/cshome/sweiss. My SHELL is /bin/bash.
If my userid were 1221, then the output would be
$ hwk1
My username is sweiss, my userid is 1220, and my home directory is /data/biocs/b/cshome/sweiss. The value of my DISPLAY variable is localhost:10.0.
Error Handling
Guidance
• To write this program, you’ll need to learn how to use a few of the functions and system calls we saw in Chapter 1. I suggest looking at the programs in Chapter 1 of the demos directory. There you’ll see an example from which you can start.
• What is your userid on our system? Chapter 1 shows you the command for finding it.
• The program has to print out the userid of the user who runs it. There is a function that can get that userid. What is it? A search of the man pages (apropos command) can find it for you.
• The program needs to format the output. It’s time to learn how to use printf(). The printf() man page (Section 3 of the man pages, not Section 1) is long but it has everything that you need to know. The demo programs are a good starting point as well.
• Because the program has to print a single sentence with the values of various environment variables, it will need to copy strings. This will be clear when you read Chapter 1 carefully and when you read the appropriate man pages. Functions for copying strings are abundant in C. If you’ve never used any, you can either:
– read the C Language Reference Manual, Section 7.24, to learn about the functions that can do this, or
– search the man pages for a set of candidates, using apropos. If you try this, use the -a option for “anding” the search terms, and try entering “copy” and “string” together.
Instructions for Submitting the Assignment
1. Use the submithwk_cs49366 program to submit your program. It can be run on any cslab host, so login to a cslab host when you’re ready to submit. To submit, if your file is named myhwk.c, you’d enter
$ cd ~
$ submithwk_cs49366 -t 1 myhwk.c
The program will try to copy myhwk.c into the directory
/data/biocs/b/student.accounts/cs493.66/hwks/hwk1/
and if it is successful, it will display the message, “File hwk1_username.c successfully submitted.” where username is your username. You will not be able to read this file, nor will anyone else except for me. But you can double-check that the command succeeded by entering the command ls -l /data/biocs/b/student.accounts/cs493.66/hwks/hwk1
2. You can do step 1 as many times as you want. Newer versions of the file will overwrite older ones.
Grading Rubric
This assignment is 8% of your final grade. The output must be correct and the program must conform to the rules written in the Programming Rules document on the class’s webpage. It must be thoroughly documented.