Operating System Lab

Operating system lab

Quick Links

• Experiment 1
• Experiment 2

Theory:

• An operating system (OS) is software that manages and handles the hardware and software resources of a system. It provides intrection between users of computers and computer hardware.
• An operating system is responsible for managing and controlling all the activities and sharing of computer resources.
• An operating system is a low-level software that includes all the basic functions like processor management, memory management, error detection, etc.

Abstract view of a computer system.

Hardware requirements

• Processor: 1 GHz or faster processor
• RAM: 1 GB for 32-bit or 2 GB for 64-bit
• Storage space: 16 GB for 32-bit OS or 20 GB for 64-bit OS.
• Display: 800 x 6009 with WDDM driver

Software requirements

• Graphics Card: Direct X9 or later with WDDM 1.0 driver

Hardware requirements

• Processor: Minimum of 1 GHz processor
• RAM: Minimum of 1 GB RAM
• Storage space: Minimum of 10 GB free disk space

Software requirements

• UNIX-compatible operating system, such as Sun Solaris, IBM AIX, HP-UX, etc.
• Compiler and development tools
• X Window System for graphical user interface
• Networking tools for network communication

Hardware Requirements:

• Processor: Minimum of 1 GHz processor
• RAM: Minimum of 1 GB RAM (2 GB or more recommended for better performance)
• Storage space: Minimum of 10 GB free disk space (20 GB or more recommended for better performance)

Software Requirements:

• Linux distribution, such as Ubuntu, Fedora, CentOS, Debian, etc.
• Graphical user interface
• Compiler and development tools
• Networking tools for network communication

Hardware Requirements:

• Processor: Minimum of Pentium 233 MHz processor (300 MHz or higher)
• RAM: Minimum of 64 MB RAM (128 MB or higher)
• Storage space: Minimum of 1.5 GB free disk space

Software Requirements:

• Windows XP operating system
• DirectX 9 graphics device with WDDM driver (optional for graphical user interface)
• Networking tools for network communication (optional)

Hardware Requirements:

• Processor: Minimum of 1 GHz processor (1 GHz or higher)
• RAM: Minimum of 1 GB RAM (2 GB or higher)
• Storage space: Minimum of 16 GB free disk space (20 GB or higher)

Software Requirements:

• Windows 7 or Windows 8 operating system
• DirectX 9 graphics device with WDDM 1.0 or higher driver (optional for graphical user interface)
• Networking tools for network communication

Process Management: Process management uses certain system calls. They are explained below.

• fork(): system call is used to create a new process.
• exec(): system call is used to run a new program.
• wait(): system call is used to make the process to wait.
• exit(): system call is used to terminate the process.
• getpid(): system call is used to find the unique process id.
• getppid(): system call is used to find the parent process id.
• nice(): system call is used to bias the currently running process property.

Example program for example of fork()

#include <stdio.h>
#include <sys/types.h>
main()
{
  int pid;
  pid = fork();
  if (pid == 0)
  {
    printf("id of the child process is=%d\n", getpid());
    printf("id of the parent process is=%d\n", getppid());
  }
  else
  {
    printf("id of the parent process is=%d\n", getpid());
    printf("id of the parent of parent process is=%d\n", getppid());
  }
}

OUTPUT

id of the parent process is=8971
id of the parent of parent process is=8970
id of the child process is=8972
id of the parent process is=8971

File Management: There are four system calls for file management,

• open(): system call is used to know the file descriptor of user-created files. Since read and write use file descriptor as their 1st parameter so to know the file descriptor open()system call is used.
• read(): system call is used to read the content from the file. It can also be used to read the input from the keyboard by specifying the 0 as file descriptor.
• write(): system call is used to write the content to the file.
• close(): system call is used to close the opened file, it tells the operating system that you are done with the file and close the file.

Example program for file management

#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <stdio.h>
int main()
{
  int n, fd;
  char buff[50];
  printf("Enter text to write in the file:\n");
  n = read(0, buff, 50);
  fd = open("file", O_CREAT | O_RDWR, 0777);
  write(fd, buff, n);
  write(1, buff, n);
  int close(int fd);
  return 0;
}
 

OUTPUT

Enter text to write in the file:
hi how r u?
hi how r u?

Input/Output System Calls: Basically there are total 5 types of I/O system calls:

• create(): Used to Create a new empty file.
• open(): Used to Open the file for reading, writing or both.
• close(): Tells the operating system you are done with a file descriptor and Close the filewhich pointed by fd.
• read(): From the file indicated by the file descriptor fd, the read() function reads bytesof input into the memory area indicated by buf.
• write(): Writes bytes from buf to the file or socket associated with fd.

Example program for Input/output System Calls

#include <stdio.h>
#include <unistd.h>
 
int main()
{
  char buffer[100];
  int n;
 
  // Read input from the user
  write(STDOUT_FILENO, "Enter a message: ", 17);
  n = read(STDIN_FILENO, buffer, 100);
 
  // Write the input back to the user
  write(STDOUT_FILENO, "You entered: ", 13);
  write(STDOUT_FILENO, buffer, n);
 
  return 0;
}

OUTPUT

Enter a message: helo
You entered: helo

See Also

• Operating System