Description
Question-1 [30 points]:
Skills tested:
● Ability to explore “man” pages for new shell commands
● Making multiple shell commands work together
Your task here is to draft a single line shell command that depicts a colorful animal
uttering a Chuck Norris fact.You will need to do this using the following commands:
1. lolcat
2. cowsay
3. jq (https://stedolan.github.io/jq/)
4. curl (to fetch a Chuck Norris joke from a web server)
Rules:
1. You should use all the commands given above.
2. You cannot use any other commands.
3. Each time your command is run, a Chuck Norris joke should be fetched randomly
by using this API – https://www.icndb.com/api/ . You should use curl to fetch the
joke. There are some crude and vulgar jokes in icndb jokes repository. If you
want to avoid these offensive jokes, consider searching for the “nerdy” category
jokes and excluding the “explicit” category jokes when using the API.
4. The API returns a JSON file which needs to be parsed with jq command.
5. Use cowsay to draw the animal. Cowsay has many different animal options to
pick. Read cowsay’s man page to figure out what these options are. You can pick
any option that starts with the first letter of one of your names. For example,
in my case I have 2 letter options: P and V as my name is Phani Vadrevu. I found
that there are 2 options I can pick: “pony” or “vader” (for Darth Vader, the Star
Wars character). Similarly, everyone needs to pick their own animal to get
full credit for this question. Don’t submit your answers with the default
animal provided by cowsay.
6. Make sure no new file is being written to disk permanently as a result of
running this command.
7. Use lolcat to color the animal like a rainbow.
8. Except for curl, the other tools are probably not installed on your machine.
Please install them before trying to use them. Debian-like OS users can use the
apt-get command to install these tools easily.
Submission Requirements:
The final one-line shell command and a screenshot of one of the random jokes
produced should be added to the Assignment’s main PDF file. For your reference, one
of the random Chuck Norris facts my command produced is shown below:
Question-2 [40 points]
Skills tested:
● Understanding and making system calls such as fork(), pid(), ppid() etc.
● General programming knowledge: Getting familiar with a graphing library (such
as graphviz)
Please do the below tasks:
Task 1: Write C-language code that does fork()calls in a loop as below:
for (i= 1 to n) {
fork()
}
The value of n should be input from the user. The program should also output the
following to a file for each process:
● Process ID
● Parent process ID
Note: Sometimes, a parent process exits before the child makes a system call to find the
parent process ID. In these cases, you will get an incorrect parent process ID. In order
to prevent this you can either have your code sleep for a little bit (like a second) before
exiting or use a waitpid() call at the end of your code.
Task 2: Write another program (in a language of your choice) to parse the file
that was output above and build a Process Tree. Every node should represent a
process and must display its Process ID. Every node should also have a “Level”
field which indicates how far it is (in terms of nodes) from the root node of the
process tree. For example, the grand child of the process tree’s root will have a
“Level” of 2.
Here’s an example of a Process Tree that your program might build if the
parameter n is 2. I built this using the awesome graphviz library and a Python
interface for it. (You can do a little bit of digging and find ways to use graphviz
with C, C++ or Java as well). Both the Level and Process ID should be shown in
each node.
Submission Requirements:
1. Include Task-1’s source code as a separate file in submission.
2. Include Task-2’s source code as a separate file in submission.
3. Run Task-1’s code with n=4. Then, use the output file of Task-1 to run Task-2.
Include the output file from Task-1 and network graph from Task-2 in the Main
PDF file.
4. Repeat 3. above for n=5.
Question-3 [10 points]
Skills tested:
● Understanding of fork(), waitpid().
Modify your code from Question-2’s Task-1 to make sure that the parent waits for the
child to die soon after the fork and then breaks from the loop and exits. Here’s some
skeletal pseudo code for that loop:
for (i= 1 to n) {
pid = fork()
…………………
if parent:
waitpid(pid)
break
}
Submission Requirements:
1. Add this modified source code for Task-1 as a separate file.
2. Run the above modified source code on n=3 and n=5. Then, run Task-2’s code
(from Question 2) on the output file produced by the modified source code.
Include these 2 modified network graphs output by Task-2’s code in the Main
PDF file.
Question-4 [20 points]:
Skills tested:
● Understanding of fork().
Modify your code from Question-2’s Task-1 to make it print “Level” as defined in
Question-2’s Task-2. This will mean that each process needs to keep track of what level
it is in by itself. Make sure that these “Level” values match the “Level” values that would
be computed by Question-2’s Task-2 code.
Submission Requirements:
1. Add the modified source code for Task-1 as a separate file.
2. Run the modified source code on n=3 and n=5. Include the outputs from these
runs in the Main PDF file.
Question-5 [20 points]:
Skills tested:
1. Reading and understanding Chapter-1 material from other sources. Connecting
this with what we learnt in class.
Read this article and answer the questions that follow:
https://thorstenball.com/blog/2014/06/13/where-did-fork-go/
1. Why did the article’s author not see fork() calls in strace output?
2. Which system call did the author see instead of fork() in strace?
3. What is the library whose library procedure was called by the author’s code?
4. The below diagram from the textbook shows how the read() call is performed.
Draw a similar diagram describing the fork() call that the author made. Hint: This
will be simpler than textbook’s diagram as fork has no parameters. (So, no step
1, 2 or 3). However, unlike in the textbook, step 4 and step 5 will not have
matching names due to the reason you mentioned for Part-1 above. Make sure
you show these different names clearly in your answer.
Submission Requirements:
1. Include all the answers for the 4 questions above in the main PDF file. Question
4 will need a diagram which should also be included in the PDF file.