Exercise 1.1: Process creation and termination system calls (Total points: 50 ).
The first exercise deals using process creation system call, fork(). You need to write a program that spawns a child process, using the fork() system call. The child process reads a CSV file, presented with the assignment, that has (fake) student IDs and grades of various assignments. This child process computes the average score of each student for section ‘A’, and thereafter prints the details of these students (of section ‘A’, i.e.). The parent process does the same operation, on the same CSV file but for students of section ‘B’. The parent process must wait for the child process to terminate, by using the system call waitpid(). The child process must call the exit() system call once its execution ends.
Exercise 1.2: Basic Linux/Unix shell (Total points: 50 ).
Linux (and other Unix like OSes), have “shells” or programs which present a command line interface to users to type commands in. In this assignment you need to use standard C libraries, including Linux system calls such as fork(),exec() family system calls and wait() family of system calls. There are two kinds of commands – “internal” and “external”. Internal
commands are those which are interpreted by the shell program itself, with- out requiring a different program to handle the expected operations (of the
said command). Examples of internal commands are like ‘cd’, ‘pwd’, ‘exit’ etc. External commands on the other hand relate to commands which are not handled directly by the shell program but by an external program. Common examples include ‘ls’, ‘cat’, ‘grep’ etc.
Task is to design your a simple shell that can handle five, internal com- mands – ‘cd’, ‘echo’, ‘history’, ‘pwd’ and ‘exit’. These commands
would be handled directly by the shell. Your shell should also be able to han- dle five external commands – ‘ls’, ‘cat’, ‘date’, ‘rm’ and ‘mkdir’. For
these external commands you need to write individual programs to handle these
commands. To handle these external commands, the shell should typically cre- ate a new process, using the fork() system call and within each process you
need to use the execl() family system call to run the individual program. The parent program must also wait for the child program to terminate using the wait() family of system calls. For each of these commands, you need not handle all the command line options. Two options per command is sufficient. You need to document which two options you are handling and need to demonstrate correct functioning of the command with respect to (atleast) your chosen options. You also need to handle corner cases such as invalid options (graceful degradation).