System calls are a way for applications to request services from the Operating System (OS). They provide a standardized interface between applications and the OS, allowing applications to interact with the underlying hardware and system resources.
A system call is typically initiated by an application program, which uses a library function to invoke the system call. The library function translates the application request into a system call and transfers control to the OS kernel. The OS kernel then performs the requested service on behalf of the application and returns the results to the application program.
Some common examples of system calls include:
- Process management: Creating, deleting, and managing processes.
- File management: Creating, opening, reading, writing, and deleting files.
- Memory management: Allocating and freeing memory.
- Device management: Managing input/output devices such as printers, scanners, and network adapters.
- Network management: Configuring network settings and managing network connections.
- Inter-process communication: Allowing processes to communicate with each other and synchronize their activities.
System calls are essential for the proper functioning of an OS, as they allow applications to access system resources in a controlled and secure manner. They provide a layer of abstraction between the application and the hardware, allowing the OS to manage resources and provide a consistent interface to applications.