Question $0$:

Run the create$\_$a$4.$sh script to generate the starter files.

Question $1$:

Write a script called, script$4\_1.$sh that extracts the First Name, Last Name and Adjusted Score columns from files with similar formatting as rand$\_$data.csv$,$ do not assume that you will always be given this particular file as input. Sort the data numerically by Adjusted Score and print the top n scores, where is n is specified on the command line as $$2$ and the filename of the data file is $$1.$

The invocation of your script may look like the following:

$./$script$4\_1.$sh rand$\_$data.csv $3$

Where for the above example, the top $3$ scores are printed.

First Name,Last Name,Adjusted Score

YoYo,Rubics,$90\mathrm{.}21$

Mariko,Sama,$73\mathrm{.}92$

Nakajima,Rocky,$71\mathrm{.}38$

Question $2$:

You suspect a file has been modified, this file is called suspect.txt$.$ You do not have a copy of original file, but you do have the file processed.txt$,$ which was generated from the original unmodified file using a bash filters.

Write a script called script$4\_2.$sh that has the inputs:

$$1,$ the suspect file

$$2,$ the processed file

You may only use the commands you've learned in class so far to solve this problem, so tools like grep, awk, sed cannot be used.

Your script will list the Student numbers that has modified letter grades. Only list each student number once to stdout.

An example invocation would be:

$./$script$4\_2.$sh suspect.txt processed.txt

May have the output:

$2367$

$2126$

$1111$

The order of the student numbers do not matter.

Click here for a hint on how to compare files

Alternative hint

Question $3$

Write a command called script$4\_3.$sh that takes in $1$ parameter $$1,$ which represent the the parent ID$.$ For the parent ID list all the process IDs of its children, and their invocation including the parameters to stdout. Kill all the child process of that parent, without killing the parent.

Example invocation:

$./$script$4\_3.$sh $19155$

May produce the following output:

$19164,$bash $/$tmp$/$test$\_$script$\_1280.$sh $10$

$19165,$bash $/$tmp$/$test$\_$script$\_1280.$sh $21$

$19166,$bash $/$tmp$/$test$\_$script$\_1280.$sh $22$

$19167,$sleep $5$h

It is a comma separated table, that list all the immediate child processes of the parent process. The $1$st column represents process id of the child, and the second column represents the invocation used to create the child. This information can be found using the $-$f option of the ps command. Remember that you script should attempt to kill all the processes listed.

A script called start$\_$process$\_$tree.sh has been provided for you to test your script. It will create $4$ background processes, sometimes you may not see the sleep $5$h process but that is okay.

You can invoke the script by using:

$./$start$\_$process$\_$tree.sh &

to have the script running the in the background, the process ID will be printed after you invoke the script in the background.

$./$start$\_$process$\_$tree.sh &

$[2]19155$

Note that when you run the script, sometimes you may see the extra output like following:

$./$start$\_$process$\_$tree.sh: line $25$: $21241$ Terminated bash $/$tmp$/$test$\_$script$\_1280.$sh $10$

$./$start$\_$process$\_$tree.sh: line $25$: $21242$ Terminated bash $/$tmp$/$test$\_$script$\_1280.$sh $21$

$./$start$\_$process$\_$tree.sh: line $25$: $21243$ Terminated bash $/$tmp$/$test$\_$script$\_1280.$sh $22$

$./$start$\_$process$\_$tree.sh: line $25$: $21244$ Terminated sleep $5$h

$21241,$bash $/$tmp$/$test$\_$script$\_1280.$sh $10$

$21242,$bash $/$tmp$/$test$\_$script$\_1280.$sh $21$

$21243,$bash $/$tmp$/$test$\_$script$\_1280.$sh $22$

$21244,$sleep $5$h

The termination messages are emitted from the stderr of the $./$start$\_$process$\_$tree.sh and not your script so you don't have to worry about them. These messages occur when the child processes are killed.