Course Title - Operating System
Topic Title –Real Time Systems
Presenter’s Name –V.VIDYASAGAR
Presenter’s ID – IARE11091
Department Name – CSE(AI&ML)
Lecture Number -14
Presentation Date – 28-08-2025
1
User Operating System Interface
• There are several ways to user interface.
• Two of the fundamental approaches are
1.Command-line interface
2. Graphical User Interface(GUI)
• The command interpreter allows the user to enter the commands
(to perform on OS) directly
• Others allow users to interface with OS via GUI
Command-line interpreter
• In some operating systems, the command line at the kernel
• Windows XP and LINUX treat it as a special program
• Systems have multiple command interpreters
• Those interpreters are called shells
• Users can choose among these several shells
• Third-party shells and user-written shells are also available
• All the shells have similar functionalities
• Provides users a choice of which shell to use
• The main functionality of and execute the next user-
specified commands
• Commands given at this time may lead to manipulation
of files (like – create, delete, list, print, copy)
• These commands can be implemented in two ways
• 1st approach is - command interpreter
• Itself has the code to execute the command
Ex: command to “delete a file”
• Causes command interpreter to jump to the selection of
code
• No. of commands determines the size of the command
interpreter
• Because each command requires its implementation
code
• 2nd approach – used by UNIX
• Implements most code through system programs
• So, it doesn't understand the code
• But we can use this to identify the file
• To delete a file in UNIX we require a “rm” Command.
• And have to load the file into memory and execute
with the “file.txt “ parameter
rm file.txt
Graphical User Interface(GUI)
• It is another strategy for interfacing with OS
• Here, rather than entering commands directly via the
command line we use mouse-based windows and a
menu system
• The user moves the mouse to position its pointer
• After positioning the mouse by clicking on mouse we
can invoke a program or can select a file.
Thank You
