What is the purpose of system calls

System calls serve as the interface between user-level applications and the operating system kernel. They provide a mechanism for user processes to request services or operations that require privileged access to system resources. The main purposes of system calls are as follows:

1. Accessing Operating System Services: System calls allow user processes to access a wide range of services provided by the operating system. These services include file operations (such as opening, reading, writing, and closing files), process management (such as creating, terminating, and managing processes), memory management (such as allocating and deallocating memory), and communication with hardware devices (such as reading from or writing to devices).

2. Protection and Security: System calls enforce security and protection mechanisms by ensuring that only authorized processes can perform certain privileged operations. By mediating access to system resources, system calls prevent unauthorized access, ensure data integrity, and protect the system from malicious or unintended actions.

3. Isolation and Resource Management: System calls enable the operating system to enforce isolation between processes and manage system resources efficiently. Processes interact with the operating system through system calls to request resources such as CPU time, memory, I/O devices, and network connections. The operating system uses scheduling algorithms and resource allocation policies to manage these resources effectively and ensure fair and efficient sharing among competing processes.

4. Abstraction and Portability: System calls provide a layer of abstraction that hides the underlying hardware details and system complexities from user-level applications. This abstraction allows applications to be written in a hardware-independent manner, making them portable across different hardware platforms and operating systems. Applications interact with the operating system through a standardized set of system calls, regardless of the underlying hardware architecture or system implementation.

5. Interprocess Communication: System calls facilitate interprocess communication (IPC) by providing mechanisms for processes to communicate and synchronize their activities. Processes can use system calls such as message passing, shared memory, pipes, and sockets to exchange data, signals, and synchronization primitives. This enables collaboration and coordination among processes, allowing them to work together to achieve complex tasks or solve problems.

Overall, system calls play a crucial role in enabling user-level applications to interact with the operating system kernel and access system resources in a controlled and secure manner. They provide the foundation for building and executing applications on modern computing systems, facilitating efficient resource management, protection, and collaboration among processes.