Summary of "L-1.7: System Calls in Operating system and its types in Hindi"

Summary of "L-1.7: System Calls in Operating System and Its Types in Hindi"

This video explains the concept of system calls in operating systems, their purpose, and their types. It is presented in Hindi and primarily targets students preparing for competitive exams like GATE.

Main Ideas and Concepts

User Mode vs Kernel Mode:
- User mode is where applications and programs run.
- Kernel mode is where the core of the operating system operates and manages hardware and resources.
- To access OS functionalities or hardware devices, programs must switch from user mode to kernel mode.
System Call Definition:
- A system call is a programmatic interface that allows a user mode process to request services from the kernel.
- It acts as a bridge between user mode and kernel mode.
- Example: Calculations like 2+2 happen in user mode, but printing the result on the monitor requires a system call to access the device through the kernel.
Direct vs Indirect Use of System Calls:
- Some operating systems like Linux allow direct use of system calls (e.g., read(), write(), open(), fork()()).
- In other systems, users typically use APIs or library functions (e.g., printf()()) which internally invoke system calls.
- Regardless of direct or indirect use, the kernel executes the actual operation.
Number of System Calls:
- Varies by OS; Linux has hundreds, Windows 7 has around 700 system calls.

Categories of System Calls

File-related System Calls:
- Used to create, open, read, write, and close files.
- Example: When a program runs, it becomes a process in RAM and accesses files via system calls because the process itself lacks direct privileges.
Device-related System Calls:
- For accessing hardware devices like printers, monitors, hard disks.
- User processes cannot access hardware directly; they must request permission through system calls.
- Includes operations like reading/writing devices and controlling them (e.g., using ioctl).
Information-related System Calls:
- Retrieve metadata or attributes of processes and files.
- Examples:
  - getpid() – get process ID
  - getppid() – get parent process ID
  - Access system time, date, or device information.
Process Control System Calls:
- Manage processes: creation, execution, termination.
- Example: fork()() creates a child process, enabling multiprocessing.
- Includes synchronization calls like wait() and signal handling.
- Used for memory allocation and managing semaphores.
Communication-related System Calls:
- Facilitate inter-process communication (IPC).
- Methods include pipes (pipe()), shared memory (shmget()), and connection management.
Protection and Security System Calls:
- Manage file permissions and security.
- Examples: chmod()() to change file permissions, umask() for default permission settings.

Important Lessons

System calls are essential for controlled access to OS resources and hardware.
They ensure security and stability by preventing direct user access to kernel mode.
Understanding system calls helps grasp how operating systems manage processes, files, devices, and communication.
Memorization of every system call is unnecessary; focus on understanding their purpose and categories.

Speakers / Sources

The video features a single speaker (likely the instructor or tutor from "GATE Smashers") explaining the topic in Hindi.
No other speakers or external sources are mentioned.