Q$\mathrm{.}2.(15$ points$)$

a$.$ Write the Linux command$($s$)$ to change the permissions of your file $/$usr$/$home$/$file$.$dat as follows:

$-$you can read, write and execute

$-$the users in your group can read and execute, but cannot write

$-$rest of users can only read

b$.$ Write the following Linux shell script: From the processes that are currently running, find and display the number of processes that are run by your user name and by other users.

c$.$ Suppose the file $/$usr$/$home$/$students$.$dat contains student information as: Name, id$,$ Birthday, Department Write a Linux shell script to sort the file according to Name. Then print only the Name and Department of the last student.