Description: The ‘System Call’ is a fundamental interface that allows user programs to interact with the operating system kernel. Through these calls, programs can request essential services such as file management, memory allocation, inter-process communication, and hardware manipulation. System calls act as a bridge between application software and hardware, enabling programs to perform tasks that require special privileges not available in user space. Each system call has a unique number and is invoked through an interrupt or a specific mechanism of the operating system. This ensures that requests are handled safely and efficiently, protecting the integrity of the system. In various environments, system calls are crucial for resource management and user input, while in many operating systems, these calls are essential for basic functioning and application execution. The correct implementation and use of system calls are vital for the performance and stability of the operating system as a whole.
History: System calls have their roots in early operating systems from the 1960s, where they were introduced to allow user programs to access system resources in a controlled manner. Over time, they have evolved and been standardized, especially with the advent of UNIX in 1969, which popularized the concept and established a set of system calls that have been maintained in many modern operating system variants.
Uses: System calls are used in a variety of contexts, including file management, process creation and termination, inter-process communication, and memory management. They are essential for any application that needs to interact with hardware or perform operations that require elevated permissions.
Examples: An example of a system call is ‘open()’, which is used to open files in UNIX systems. Another example is ‘fork()’, which allows a process to create a new child process, essential for multitasking in operating systems.
