Question

Task: there are mainly five types of system calls: Process Control, File Management, Device
Management, Information Maintenance and Communication. Please write two python programs
to implement the above two types of system calls.

Answer 1

Lets us first look at some terms that will help us understand system calls better and how they are executed.

Kernel - The kernel is the heart of a computer's operating system. It is in charge of everything that a computer executes such as processes, files, display, memory management, etc.

A System call is a call to the kernel to signal it for a service or a resource. System calls are of many types like process, file, information, communication, and device.

Process Control - Process control refers to the procedure of creating, handling, and terminating a process by a system call to the kernel.

Process control is implemented in python by a package called the OS which has access privileges to communicate with the kernel itself and fork new child process from parent processes. Either we can use the os.fork() to fork a child process from the parent OS process itself or use a package called multiprocessing to create multiple child processes.

Let's look at a code implementation in python. The code is commented for better understanding.

import os 
# multiprocessing package
import multiprocessing 
  
# function process to depict process management
def process(): 
    # printing process id 
    print("ID of child process: {}".format(os.getpid())) 


#test function in main 
if __name__ == "__main__": 

    # parent process id
    print("ID of main process: {}".format(os.getpid())) 
  
    # creating child processes 
    child = multiprocessing.Process(target=process) 
    child_2 =  multiprocessing.Process(target=process)
    child_3 =  multiprocessing.Process(target=process)  

    # starting child processes 
    child.start() 
    child_2.start() 
    child_3.start() 

    #child process IDs 
    print("ID of child process : {}".format(child.pid)) 
    print("ID of child_2 process : {}".format(child_2.pid)) 
    print("ID of child_3 process : {}".format(child_3.pid)) 
  
    # wait until processes are finished 
    child.join() 
    child_2.join()
    child_3.join()
  

(2)

A File management system call to the kernel is used to open, read, create and modify files. Files management is an integral part of any operating system.

Let's implement a basic file management code in python that opens a file, modify it and writes to a new file by creating another file.

#open a file in read mode
file = open('cars.txt','r')

#for each line in file read
for lines in file:
    print(lines)

#open a new file in read/write/create mode
new_file = open('new_file.txt','x')

#write to the new file
new_file.write("bye")

#close the file
file.close()