Homework #2
Due: Thursday, October 16, 1996, at 6:00 PM	
Points: 130

The UNIX Environment
Submitting: Type your answers into a file called Answers, and submit it as described in the All About Homework handout. Remember, we’ll read it on the DECs, so be sure it can be read on them! (Note: if you use another file name, we will deduct 5 points.)
The purpose of these questions is to have you use the UNIX system and environment.
1.	(10 points) What is the parent directory of /?
2.	(10 points) What is the command that executes with process id (PID) 2?
3.	(10 points) How would I make an alias that will print the name of the current working directory whenever I execute the C-Shell command cd? (Assumeyou are using the C-Shell.)
The C Programming Language
Submitting: Put your program into a file called main.c, and submit it as described in the All About Homework handout. Remember, we’llcompile and run  it on the DECs, so be sure it works there!  (Note: if you use another file name, we will deduct 5 points.)
(100 points)  The purpose of this question is for you to build on your (or my) answer to program 1 to gain experience with poiinters and dynamic storage allocation..
Input Specifications
Read from the standard input.  The input is supposed to be a C program. You need not check that it is, in fact, a legal C program; your program should simply assume it is.
Output Specifications
Write to the standard output.  In the first 6 columns of each output line, print a line number followed by a period “.”. Print the input line beginning in column 9 (one tab from the left margin)..
If the line is a preprocessor control line, and the preprocessor directive is define, add the name, line number on which the define occurs, and definition to a table. When the input is finished, print the table, headed by the title “Table of Defines” and beginning on a separate page.
Other Constraints
Put the entries into an array, one definition and one name per entry. (So, you will have to use a structure for this.) The form of each entry is
struct defent {
	char *name;
	char *defn;
};
You must allocate space for the name and defn fields, but you may assume that no more than 1000 symbols will be defined.

Example Input
#define PI 3.14159
#define E 2.71828

int main(void)
{
	printf(“pi = %f, e = %f\n”, PI, E);
}
Example Output
    1.  #define PI 3.14159
    2.  #define E 2.71828
    3.  
    4.  int main(void)
    5.  {
    6.  	printf(“pi = %f, e = %f\n”, PI, E);
    7.  }

Table of Defines:
name            line                    definition
PI                1                 3.14159
E                 2                 2.71828
Extra Credit
Submitting:Create a C program called extra.c. You may copy your main.c into it and modify that (in fact, we encourage you to!)
Modify your answer so that there can be anyt number of symbols, not simply 1000..