In this assignment, you are to explore the use and programming of some system calls through the creation of a simple shell program $($you are writing a simple user$-$interface to the operating system$).$

should operate in a fashion similar to that as illustrated in the book, in Figure $1-19$:

while $($true$)\{$

print a command prompt

get a line of user input

if $($they didn't type "exit" or $"$cd$")\{$

create a child process

if $($I am the parent$)$

wait for the child

else $($I am the child$)$

directly execute the sys call

OR $-$

execute the command using a version of exec.

$\}$

$\}$

System Calls

This list may not represent all possible options, especially for the time information and the host name.

Time information: gettimeofday, localtime, strftime

Getting the host name: uname, gethostname

Creating $($making$)$ a directory: mkdir

Removing a directory: rmdir

Printing working directory: getcwd

Changing directory: chdir

Kill: kill. Note that when implementing this one, just have it send a signal $9$ to the identified PID.

Creating a child process: fork

Waiting for a child process: waitpid, wait