Question $3$: System Calls

What is the purpose of the system calls? Provide one example of system call for each category of the services provided by any typical operating system.

Task $2$: open$(),$ read$()$ and write$()$ system calls

In the lecture, we saw a demonstration regarding usage of the read$()$ and write $()$ system calls, when an array of characters is being read from the Keyboard and written onto the screen using the POSIX$-$based API.

Write a C program in which input is taken from the Keyboard and is then written onto a non$-$existing file of title "test.txt$".$ In other words, a program should be able to create a file with title "test.txt$"$ and the contents taken from Keyboard should be written in this file.

Hint: You need to use an open $()$ system call to get a file descriptor, and then use this file descriptor in the write $()$ system call.