Operating System and User Interface

As a bridge between users and computer hardware, the operating system provides a variety of interfaces for users to interact with the system. Modern operating systems usually provide the following three typical interfaces:

Command interface (job-level interface)

The command interface is an interactive method in which users send operation commands to the operating system through input devices (such as keyboards) to complete the required functions. Command interfaces can be divided into:

Online command interface (interactive command interface)

Users enter commands through the keyboard, and the system executes and returns results in real time. Commonly used for tasks such as file management, directory operations, and system access.

Sample command format:

Command arg1, arg2, ..., argn [option1, ..., optionk]

Examples: ls -l, mkdir new_folder, cp file1.txt file2.txt

Offline command interface (batch command interface)

Use JCL (Job Control Language) to write job control instructions, and the system automatically executes tasks. After submitting a job, the user cannot intervene in real time and can only wait for the task to be completed.

Program interface

The program interface consists of a series of system calls. Users can use system calls to request the underlying services and resources provided by the operating system when writing programs.

System call

It is a service interface provided by the operating system for user programs. User programs obtain system resources by calling subroutines provided by the system.
Classification of system calls:
File management class
Process control class
Storage management class
Device management class
Program control class
Information maintenance class

System call execution process

Set system call parameters.
Make service requests to the operating system through system call instructions.
The operating system completes specific operation tasks according to the request.

Graphical interface

Modern operating systems provide graphical user interfaces (GUIs), which have greatly improved in form and function compared to command interfaces and program interfaces, and provide a more friendly and intuitive user experience.

Users perform operations by selecting menu items without having to remember specific commands.

Graphics driver mode

Using graphics, icons, windows and other elements, users interact with the system by clicking, dragging and other operations, which is common in desktop operating systems and mobile operating systems.

Summary

Command interface is mainly used for precise operations and automated tasks, suitable for advanced users and batch tasks.
Program interface provides programmers with a means to request system resources and functional services, and is an important implementation method of system calls.
Graphics interface provides a more intuitive operation method, suitable for ordinary users, and reduces the learning cost.