Write a shell(born) program called prof_mailer. This program has to be interactive. The function of this program is to make the communication between the prof and students very easy as follow,

1. each class has a class list this list has info about every student which include:
last name
first name
student ID
email address
phone no.

2. The file which has the list is a colon saparated file, i.e. Abuzneid:Abdelshakour:0444333:abdel@bridgeport.edu:2035764911
Lary:Hasan:0343434:lary@aol.com:2033720912

3. Whenever an entry added to the list, the list has to be automatically sorted by the last name

4. Any prof usually teaches more than one course. Each class has to have a class list. The name of the mail list is the class name. Because a prof can teach the same class for two sections, the number of the section has to be included. i.e

cpe471_09 - Computer Communications I, section 9
cpe471_11 - Computer Communications I, section 11
cs435_09 - C and Unix, section 9

5. The prof can edit the file and add any student to the list by editing the file. The problem is the file will not sorted after that by the last
name. You have to write a program that allows the prof to create a class list for a course if it is not existent. If the class list for that course is there, another utility (could be the same utility with different key i.e -add ... ) is used to add the students to the class list. Prof can add a student in two ways

a. colon saparated line (as above)
b. the program tells the prof which field to enter one after another. I.e
ENTER THE LAST NAME:
Abuzneid
ENTER THE FIRST NAME:
Abdelshakour
ENTER SID:

6. The uniq key cam be the email address or/and SID. If the prof enter 2 entries with same key, the program will warn the prof and list him the other entry witch has the same key. The prof has the option to continue adding this entry or cancel
Example
THIS USER HAS THE SAME KEY AS Abdelshakour Abuzneid

ADD THIS STUDENT(Y/N)?

7. It is very hard to keep running the add program to add every user, specially at the beginning of the semester because the prof has to add 20 or more students at one time. Make an option in the program that more than one student can be added to the program in one execution. Example $add -1l -50
ENTER STUDENT 2:
ENTER STUDENT 50:

8. Some students give you email (or another entry) but they want you to email them to another address. Then you have to modify this entry for that (noisy) student. The prof has to have the modify program to modify this entry. Example