Question No. 1 [10 points]
Explore and find the purpose of the following routines:
Dup()
Dup2()
(a) What is main difference between them?
In UNIX, on the command line, we often use pipes to connect programs so that the standard output
of one program becomes the standard input of the next, For example, the command:
# last | sort will execute the last command and pipes its output to the sort command. The
redirection is done by the command line option “|”.
(b) Can dup and dup2 be used to make such sort of functionality? If yes, how? If no, give
reason(s) why?
Question No. 2 [20 points]
You are required to implement a Unix shell that supports the following commands:
rm
mv
mkdir
rmdir
Please note that you have to provide your own implementation, you are not allowed to use C
function that takes an argument of a Unix command and executes that command.
Question No. 3 [30 points]
Write a C program that creates two threads using the POSIX threading library. In the main program,
create a file ‘data.txt’. First thread writes some numeric value to the file along with the system time,
the second thread reads the data from the ‘data.txt’ file and displays the following information on
standard output, i.e., computer screen.
Numeric Value Time when Value was written to the File Time when Value was Read by the Thread
You are required to use synchronization primitives provided by the UNIX OS to ensure consistency
and serial access to the file, i.e., a thread can only read data from the file, if the other thread has
written new data to the file, and a file is only accessed by a thread if the other thread is not using
the file. The thread responsible for writing data to the file writes to the file after 500 ms. The
program terminates when Ctrl+C is hit by the user.
Question No. 4 [20 points]
a. What are the motivations to the design development of Mach Kernel foundation
development?
b. Differentiate between the Task and Thread in Mach design.
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